RESUMEN

Extracellular acyl-coenzyme A binding protein [ACBP encoded by diazepam binding inhibitor (DBI)] is a phylogenetically ancient appetite stimulator that is secreted in a nonconventional, autophagy-dependent fashion. Here, we show that low ACBP/DBI plasma concentrations are associated with poor prognosis in patients with anorexia nervosa, a frequent and often intractable eating disorder. In mice, anorexia induced by chronic restraint stress (CRS) is accompanied by a reduction in circulating ACBP/DBI concentrations. We engineered a chemical-genetic system for the secretion of ACBP/DBI through a biotin-activatable, autophagy-independent pathway. In transgenic mice expressing this system in hepatocytes, biotin-induced elevations in plasma ACBP/DBI concentrations prevented anorexia induced by CRS or chemotherapeutic agents including cisplatin, doxorubicin, and paclitaxel. ACBP/DBI reversed the CRS or cisplatin-induced increase in plasma lipocalin-2 concentrations and the hypothalamic activation of anorexigenic melanocortin 4 receptors, for which lipocalin-2 is an agonist. Daily intravenous injections of recombinant ACBP/DBI protein or subcutaneous implantation of osmotic pumps releasing recombinant ACBP/DBI mimicked the orexigenic effects of the chemical-genetic system. In conclusion, the supplementation of extracellular and peripheral ACBP/DBI might constitute a viable strategy for treating anorexia.

Asunto(s)

Anorexia , Inhibidor de la Unión a Diazepam , Animales , Inhibidor de la Unión a Diazepam/metabolismo , Anorexia/tratamiento farmacológico , Anorexia/metabolismo , Humanos , Ratones Transgénicos , Ratones , Anorexia Nerviosa/metabolismo , Anorexia Nerviosa/tratamiento farmacológico , Lipocalina 2/metabolismo , Lipocalina 2/sangre , Hipotálamo/metabolismo , Masculino , Femenino , Ratones Endogámicos C57BL , Restricción Física , Hepatocitos/metabolismo , Hepatocitos/efectos de los fármacos

RESUMEN

In recent years, primary familial brain calcification (PFBC), a rare neurological disease characterized by a wide spectrum of cognitive disorders, has been associated to mutations in the sodium (Na)-Phosphate (Pi) co-transporter SLC20A2. However, the functional roles of the Na-Pi co-transporters in the brain remain still largely elusive. Here we show that Slc20a1 (PiT-1) and Slc20a2 (PiT-2) are the most abundant Na-Pi co-transporters expressed in the brain and are involved in the control of hippocampal-dependent learning and memory. We reveal that Slc20a1 and Slc20a2 are differentially distributed in the hippocampus and associated with independent gene clusters, suggesting that they influence cognition by different mechanisms. Accordingly, using a combination of molecular, electrophysiological and behavioral analyses, we show that while PiT-2 favors hippocampal neuronal branching and survival, PiT-1 promotes synaptic plasticity. The latter relies on a likely Otoferlin-dependent regulation of synaptic vesicle trafficking, which impacts the GABAergic system. These results provide the first demonstration that Na-Pi co-transporters play key albeit distinct roles in the hippocampus pertaining to the control of neuronal plasticity and cognition. These findings could provide the foundation for the development of novel effective therapies for PFBC and cognitive disorders.

Asunto(s)

Cognición , Simportadores , Transporte Iónico , Plasticidad Neuronal/genética , Fosfatos

RESUMEN

Chronic stress constitutes a major risk factor for depression that can disrupt various aspects of homeostasis, including the gut microbiome (GM). We have recently shown that GM imbalance affects adult hippocampal (HPC) neurogenesis and induces depression-like behaviors, with the exact mechanisms being under active investigation. Here we hypothesized that the vagus nerve (VN), a key bidirectional route of communication between the gut and the brain, could relay the effects of stress-induced GM changes on HPC plasticity and behavior. We used fecal samples derived from mice that sustained unpredictable chronic mild stress (UCMS) to inoculate healthy mice and assess standard behavioral readouts for anxiety- and depressive-like behavior, conduct histological and molecular analyses for adult HPC neurogenesis and evaluate neurotransmission pathways and neuroinflammation. To study the potential role of the VN in mediating the effects of GM changes on brain functions and behavior, we used mice that sustained subdiaphragmatic vagotomy (Vx) prior the GM transfer. We found that inoculation of healthy mice with GM from UCMS mice activates the VN and induces early and sustained changes in both serotonin and dopamine neurotransmission pathways in the brainstem and HPC. These changes are associated with prompt and persistent deficits in adult HPC neurogenesis and induce early and sustained neuroinflammatory responses in the HPC. Remarkably, Vx abrogates adult HPC neurogenesis deficits, neuroinflammation and depressive-like behavior, suggesting that vagal afferent pathways are necessary to drive GM-mediated effects on the brain.

Asunto(s)

Microbioma Gastrointestinal , Ratones , Animales , Microbioma Gastrointestinal/fisiología , Enfermedades Neuroinflamatorias , Encéfalo/metabolismo , Nervio Vago/fisiología , Depresión/metabolismo , Estrés Psicológico

RESUMEN

Cajal-Retzius cells (CRs) are transient neurons, disappearing almost completely in the postnatal neocortex by programmed cell death (PCD), with a percentage surviving up to adulthood in the hippocampus. Here, we evaluate CR's role in the establishment of adult neuronal and cognitive function using a mouse model preventing Bax-dependent PCD. CRs abnormal survival resulted in impairment of hippocampus-dependent memory, associated in vivo with attenuated theta oscillations and enhanced gamma activity in the dorsal CA1. At the cellular level, we observed transient changes in the number of NPY+ cells and altered CA1 pyramidal cell spine density. At the synaptic level, these changes translated into enhanced inhibitory currents in hippocampal pyramidal cells. Finally, adult mutants displayed an increased susceptibility to lethal tonic-clonic seizures in a kainate model of epilepsy. Our data reveal that aberrant survival of a small proportion of postnatal hippocampal CRs results in cognitive deficits and epilepsy-prone phenotypes in adulthood.

Asunto(s)

Hipocampo , Neuronas , Hipocampo/fisiología , Trastornos de la Memoria/genética , Trastornos de la Memoria/metabolismo , Neuronas/metabolismo , Células Piramidales/fisiología , Convulsiones/genética , Convulsiones/metabolismo , Animales , Ratones

RESUMEN

Cajal-Retzius cells (CRs) are a class of transient neurons in the mammalian cortex that play a critical role in cortical development. Neocortical CRs undergo almost complete elimination in the first two postnatal weeks in rodents and the persistence of CRs during postnatal life has been detected in pathological conditions related to epilepsy. However, it is unclear whether their persistence is a cause or consequence of these diseases. To decipher the molecular mechanisms involved in CR death, we investigated the contribution of the PI3K/AKT/mTOR pathway as it plays a critical role in cell survival. We first showed that this pathway is less active in CRs after birth before massive cell death. We also explored the spatio-temporal activation of both AKT and mTOR pathways and reveal area-specific differences along both the rostro-caudal and medio-lateral axes. Next, using genetic approaches to maintain an active pathway in CRs, we found that the removal of either PTEN or TSC1, two negative regulators of the pathway, lead to differential CR survivals, with a stronger effect in the Pten model. Persistent cells in this latter mutant are still active. They express more Reelin and their persistence is associated with an increase in the duration of kainate-induced seizures in females. Altogether, we show that the decrease in PI3K/AKT/mTOR activity in CRs primes these cells to death by possibly repressing a survival pathway, with the mTORC1 branch contributing less to the phenotype.

Asunto(s)

Ácido Kaínico , Proteínas Proto-Oncogénicas c-akt , Animales , Femenino , Ácido Kaínico/toxicidad , Proteínas Proto-Oncogénicas c-akt/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Serina-Treonina Quinasas TOR/metabolismo , Convulsiones/inducido químicamente , Mamíferos/metabolismo

RESUMEN

Mutations in the Cystic Fibrosis Transmembrane Conductance Regulator gene (CFTR) are responsible for Cystic Fibrosis (CF). The most common CF-causing mutation is the deletion of the 508th amino-acid of CFTR (F508del), leading to dysregulation of the epithelial fluid transport in the airway's epithelium and the production of a thickened mucus favoring chronic bacterial colonization, sustained inflammation and ultimately respiratory failure. c407 is a bis-phosphinic acid derivative which corrects CFTR dysfunction in epithelial cells carrying the F508del mutation. This study aimed to investigate c407 in vivo activity in the F508del Cftrtm1Eur murine model of CF. Using nasal potential difference measurement, we showed that in vivo administration of c407 by topical, short-term intraperitoneal and long-term subcutaneous route significantly increased the CFTR dependent chloride (Cl-) conductance in F508del Cftrtm1Eur mice. This functional improvement was correlated with a relocalization of F508del-cftr to the apical membrane in nasal epithelial cells. Importantly, c407 long-term administration was well tolerated and in vitro ADME toxicologic studies did not evidence any obvious issue. Our data provide the first in vivo preclinical evidence of c407 efficacy and absence of toxicity after systemic administration for the treatment of Cystic Fibrosis.

Asunto(s)

Regulador de Conductancia de Transmembrana de Fibrosis Quística , Fibrosis Quística , Animales , Cloruros , Fibrosis Quística/genética , Regulador de Conductancia de Transmembrana de Fibrosis Quística/metabolismo , Transporte Iónico , Ratones , Mutación , Ácidos Fosfínicos

RESUMEN

Crouzon syndrome with acanthosis nigricans (CAN, a rare type of craniosynostosis characterized by premature suture fusion and neurological impairments) has been linked to a gain-of-function mutation (p.Ala391Glu) in fibroblast growth factor receptor 3 (FGFR3). To characterize the CAN mutation's impact on the skull and on brain functions, we developed the first mouse model (Fgfr3A385E/+) of this syndrome. Surprisingly, Fgfr3A385E/+ mice did not exhibit craniosynostosis but did show severe memory impairments, a structurally abnormal hippocampus, low activity-dependent synaptic plasticity, and overactivation of MAPK/ERK and Akt signaling pathways in the hippocampus. Systemic or brain-specific pharmacological inhibition of FGFR3 overactivation by BGJ398 injections rescued the memory impairments observed in Fgfr3A385E/+ mice. The present study is the first to have demonstrated cognitive impairments associated with brain FGFR3 overactivation, independently of skull abnormalities. Our results provide a better understanding of FGFR3's functional role and the impact of its gain-of-function mutation on brain functions. The modulation of FGFR3 signaling might be of value for treating the neurological disorders associated with craniosynostosis.

Asunto(s)

Acantosis Nigricans , Disostosis Craneofacial , Craneosinostosis , Acantosis Nigricans/complicaciones , Acantosis Nigricans/genética , Animales , Encéfalo , Disostosis Craneofacial/complicaciones , Disostosis Craneofacial/genética , Craneosinostosis/genética , Modelos Animales de Enfermedad , Trastornos de la Memoria/genética , Ratones , Receptor Tipo 3 de Factor de Crecimiento de Fibroblastos/genética

RESUMEN

Acyl coenzyme A binding protein (ACBP), also known as diazepam binding inhibitor (DBI) is a multifunctional protein with an intracellular action (as ACBP), as well as with an extracellular role (as DBI). The plasma levels of soluble ACBP/DBI are elevated in human obesity and reduced in anorexia nervosa. Accumulating evidence indicates that genetic or antibody-mediated neutralization of ACBP/DBI has anorexigenic effects, thus inhibiting food intake and inducing lipo-catabolic reactions in mice. A number of anorexiants have been withdrawn from clinical development because of their side effects including an increase in depression and suicide. For this reason, we investigated the psychiatric impact of ACBP/DBI in mouse models and patient cohorts. Intravenously (i.v.) injected ACBP/DBI protein conserved its orexigenic function when the protein was mutated to abolish acyl coenzyme A binding, but lost its appetite-stimulatory effect in mice bearing a mutation in the γ2 subunit of the γ-aminobutyric acid (GABA) A receptor (GABAAR). ACBP/DBI neutralization by intraperitoneal (i.p.) injection of a specific mAb blunted excessive food intake in starved and leptin-deficient mice, but not in ghrelin-treated animals. Neither i.v. nor i.p. injected anti-ACBP/DBI antibody affected the behavior of mice in the dark-light box and open-field test. In contrast, ACBP/DBI increased immobility in the forced swim test, while anti-ACBP/DBI antibody counteracted this sign of depression. In patients diagnosed with therapy-resistant bipolar disorder or schizophrenia, ACBP/DBI similarly correlated with body mass index (BMI), not with the psychiatric diagnosis. Patients with high levels of ACBP/DBI were at risk of dyslipidemia and this effect was independent from BMI, as indicated by multivariate analysis. In summary, it appears that ACBP/DBI neutralization has no negative impact on mood and that human depression is not associated with alterations in ACBP/DBI concentrations.

Asunto(s)

Inhibidor de la Unión a Diazepam/metabolismo , Trastornos Mentales/metabolismo , Animales , Apetito , Conducta Animal , Índice de Masa Corporal , Oscuridad , Inhibidor de la Unión a Diazepam/sangre , Conducta Alimentaria , Inmovilización , Masculino , Trastornos Mentales/sangre , Trastornos Mentales/diagnóstico , Síndrome Metabólico/sangre , Ratones Endogámicos C57BL , Receptores de GABA-A/metabolismo , Natación/fisiología

RESUMEN

Autophagy agonists have been proposed to slow down neurodegeneration. Spermidine, a polyamine that acts as an autophagy agonist, is currently under clinical trial for the treatment of age-related memory decline. How Spermidine and other autophagy agonists regulate memory and synaptic plasticity is under investigation. We set up a novel mouse model of mild cognitive impairment (MCI), in which middle-aged (12-month-old) mice exhibit impaired memory capacity, lysosomes engulfed with amyloid fibrils (ß-amyloid and α-synuclein) and impaired task-induced GluA1 hippocampal post-translation modifications. Subchronic treatment with Spermidine as well as the autophagy agonist TAT-Beclin 1 rescued memory capacity and GluA1 post-translational modifications by favouring the autophagy/lysosomal-mediated degradation of amyloid fibrils. These findings provide new mechanistic evidence on the therapeutic relevance of autophagy enhancers which, by improving the degradation of misfolded proteins, slow down age-related memory decline.

Asunto(s)

Autofagia/genética , Disfunción Cognitiva/genética , Memoria/efectos de los fármacos , Envejecimiento , Animales , Modelos Animales de Enfermedad , Ratones

RESUMEN

BACKGROUND: Formation and maintenance of appropriate neural networks require tight regulation of neural stem cell proliferation, differentiation, and neurogenesis. microRNAs (miRNAs) play an important role in brain development and plasticity, and dysregulated miRNA profiles have been linked to neurodevelopmental disorders including autism, schizophrenia, or intellectual disability. Yet, the functional role of miRNAs in neural development and postnatal brain functions remains unclear. METHODS: Using a combination of cell biology techniques as well as behavioral studies and brain imaging, we characterize mouse models with either constitutive inactivation or selectively hippocampal knockdown of the neurodevelopmental disease-associated gene Mir146a, the most commonly deregulated miRNA in developmental brain disorders (DBD). RESULTS: We first show that during development, loss of miR-146a impairs the differentiation of radial glial cells, neurogenesis process, and neurite extension. In the mouse adult brain, loss of miR-146a correlates with an increased hippocampal asymmetry coupled with defects in spatial learning and memory performances. Moreover, selective hippocampal downregulation of miR-146a in adult mice causes severe hippocampal-dependent memory impairments indicating for the first time a role for this miRNA in postnatal brain functions. CONCLUSION: Our results show that miR-146a expression is critical for correct differentiation of neural stem cell during brain development and provide for the first time a strong argument for a postnatal role of miR-146a in regulating hippocampal-dependent memory. Furthermore, the demonstration that the Mir146a-/- mouse recapitulates several aspects reported in DBD patients, including impaired neurogenesis, abnormal brain anatomy, and working and spatial memories deficits, provides convincing evidence that the dysregulation of miR146a contributes to the pathogenesis of DBDs.

Asunto(s)

Aprendizaje , Trastornos de la Memoria/genética , MicroARNs , Células-Madre Neurales/citología , Trastornos del Neurodesarrollo/genética , Animales , Células Cultivadas , Regulación hacia Abajo , Hipocampo/metabolismo , Ratones Transgénicos , Neurogénesis

RESUMEN

Age-related declines in cognitive fitness are associated with a reduction in autophagy, an intracellular lysosomal catabolic process that regulates protein homeostasis and organelle turnover. However, the functional significance of autophagy in regulating cognitive function and its decline during aging remains largely elusive. Here, we show that stimulating memory upregulates autophagy in the hippocampus. Using hippocampal injections of genetic and pharmacological modulators of autophagy, we find that inducing autophagy in hippocampal neurons is required to form novel memory by promoting activity-dependent structural and functional synaptic plasticity, including dendritic spine formation, neuronal facilitation, and long-term potentiation. We show that hippocampal autophagy activity is reduced during aging and that restoring its levels is sufficient to reverse age-related memory deficits. Moreover, we demonstrate that systemic administration of young plasma into aged mice rejuvenates memory in an autophagy-dependent manner, suggesting a prominent role for autophagy to favor the communication between systemic factors and neurons in fostering cognition. Among these youthful factors, we identify osteocalcin, a bone-derived molecule, as a direct hormonal inducer of hippocampal autophagy. Our results reveal that inducing autophagy in hippocampal neurons is a necessary mechanism to enhance the integration of novel stimulations of memory and to promote the influence of systemic factors on cognitive fitness. We also demonstrate the potential therapeutic benefits of modulating autophagy in the aged brain to counteract age-related cognitive impairments.

Asunto(s)

Envejecimiento/fisiología , Autofagia/fisiología , Hipocampo/fisiología , Trastornos de la Memoria , Memoria/fisiología , Animales , Autofagia/efectos de los fármacos , Autofagia/genética , Modelos Animales de Enfermedad , Masculino , Memoria/efectos de los fármacos , Trastornos de la Memoria/fisiopatología , Ratones , Ratones Endogámicos C57BL

RESUMEN

That osteocalcin (OCN) is necessary for hippocampal-dependent memory and to prevent anxiety-like behaviors raises novel questions. One question is to determine whether OCN is also sufficient to improve these behaviors in wild-type mice, when circulating levels of OCN decline as they do with age. Here we show that the presence of OCN is necessary for the beneficial influence of plasma from young mice when injected into older mice on memory and that peripheral delivery of OCN is sufficient to improve memory and decrease anxiety-like behaviors in 16-mo-old mice. A second question is to identify a receptor transducing OCN signal in neurons. Genetic, electrophysiological, molecular, and behavioral assays identify Gpr158, an orphan G protein-coupled receptor expressed in neurons of the CA3 region of the hippocampus, as transducing OCN's regulation of hippocampal-dependent memory in part through inositol 1,4,5-trisphosphate and brain-derived neurotrophic factor. These results indicate that exogenous OCN can improve hippocampal-dependent memory in mice and identify molecular tools to harness this pathway for therapeutic purposes.

Asunto(s)

Cognición/fisiología , Osteocalcina/fisiología , Receptores Acoplados a Proteínas G/fisiología , Envejecimiento/fisiología , Animales , Región CA3 Hipocampal/efectos de los fármacos , Región CA3 Hipocampal/fisiología , Cognición/efectos de los fármacos , Electrofisiología , Femenino , Masculino , Aprendizaje por Laberinto/efectos de los fármacos , Aprendizaje por Laberinto/fisiología , Memoria/efectos de los fármacos , Memoria/fisiología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Osteocalcina/farmacología

RESUMEN

Reciprocal relationships between organs are essential to maintain whole body homeostasis. An exciting interplay between two apparently unrelated organs, the bone and the brain, has emerged recently. Indeed, it is now well established that the brain is a powerful regulator of skeletal homeostasis via a complex network of numerous players and pathways. In turn, bone via a bone-derived molecule, osteocalcin, appears as an important factor influencing the central nervous system by regulating brain development and several cognitive functions. In this paper we will discuss this complex and intimate relationship, as well as several pathologic conditions that may reinforce their potential interdependence.

Asunto(s)

Enfermedades Óseas Metabólicas/epidemiología , Huesos/fisiología , Encefalopatías Metabólicas/epidemiología , Encéfalo/fisiología , Comunicación Celular , Animales , Enfermedades Óseas Metabólicas/patología , Encefalopatías Metabólicas/patología , Humanos

RESUMEN

Maltreatment from the caregiver induces vulnerability to later life psychopathologies, yet attraction and comfort is sometimes provided by cues associated with early life maltreatment. We used a rat model of early life maltreatment with odor-0.5 mA shock conditioning to produce depressive-like behaviors and questioned whether stimuli associated with maltreatment would restore emotional neurobehavioral function to control levels. Pups received daily novel odor-0.5 mA shock conditioning from postnatal day 8 to 12. This procedure produces a new maternal odor that controls pups' attachment behaviors. In adulthood, either with or without the infant odor, animals received a Forced Swim Test, Sucrose Preference Test or assessment of amygdala and olfactory system functioning using field potential signal evoked by olfactory bulb paired-pulse electrical stimulation. Following neonatal odor-shock pairings, but not unpaired controls, adults without the odor present showed increased depression-like behavior in the Forced Swim Test and Sucrose Preference Test and a deficit in paired-pulse inhibition in amygdala and piriform (olfactory) cortex. All effects were brought to control levels when the infant conditioned odor was presented during behavioral and neural tests. The ability of cues associated with early life maltreatment to normalize behavior and amygdala activity suggests these cues provide adaptive value in adulthood.

Asunto(s)

Amígdala del Cerebelo/fisiología , Aprendizaje por Asociación/fisiología , Depresión/fisiopatología , Apego a Objetos , Odorantes , Vías Olfatorias/fisiología , Factores de Edad , Animales , Animales Recién Nacidos , Condicionamiento Psicológico/fisiología , Depresión/psicología , Estimulación Eléctrica/efectos adversos , Femenino , Masculino , Embarazo , Ratas , Ratas Long-Evans

RESUMEN

Here we review the neurobiology of infant odor learning in rats, and discuss the unique role of the stress hormone corticosterone (CORT) in the learning necessary for the developing rat. During the first 9 postnatal (PN) days, infants readily learn odor preferences, while aversion and fear learning are attenuated. Such restricted learning may ensure that pups only approach their mother. This sensitive period of preference learning overlaps with the stress hyporesponsive period (SHRP, PN4-14) when pups have a reduced CORT response to most stressors. Neural underpinnings responsible for sensitive-period learning include increased activity within the olfactory bulb and piriform "olfactory" cortex due to heightened release of norepinephrine from the locus coeruleus. After PN10 and with the decline of the SHRP, stress-induced CORT release permits amygdala activation and facilitates learned odor aversions and fear. Remarkably, odor preference and attenuated fear learning can be reestablished in PN10-15 pups if the mother is present, an effect due to her ability to suppress pups' CORT and amygdala activity. Together, these data indicate that functional changes in infant learning are modified by a unique interaction between the developing CORT system, the amygdala, and maternal presence, providing a learning system that becomes more flexible as pups mature.

Asunto(s)

Envejecimiento/psicología , Amígdala del Cerebelo/crecimiento & desarrollo , Aprendizaje por Asociación , Miedo/psicología , Apego a Objetos , Odorantes , Estrés Psicológico/psicología , Envejecimiento/metabolismo , Amígdala del Cerebelo/metabolismo , Animales , Animales Recién Nacidos , Corticosterona/metabolismo , Locus Coeruleus/crecimiento & desarrollo , Locus Coeruleus/metabolismo , Conducta Materna/psicología , Actividad Motora , Norepinefrina/metabolismo , Bulbo Olfatorio/crecimiento & desarrollo , Bulbo Olfatorio/metabolismo , Ratas , Estrés Psicológico/metabolismo

RESUMEN

BACKGROUND: Both abused and well cared for infants show attachment to their caregivers, although the quality of that attachment differs. Moreover, the infant's attachment to the abusive caregiver is associated with compromised mental health, especially under stress. In an attempt to better understand how abuse by the caregiver can compromise mental health, we explore the neural basis of attachment in both typical and abusive environments using infant rats, which form attachments to the mother through learning her odor. Here, we hypothesize that the neural circuitry for infant attachment differs based on the quality of the attachment, which can be uncovered during stressful situations. METHODS: We used infant rats to compare infant attachment social behaviors and supporting neurobiology using natural maternal odor, as well as two odor-learning attachment paradigms: odor-stroke (mimics typical attachment) and odor-.5 mA shock conditioning (mimics abusive attachment). Next, to uncover differences in behavior and brain, these pups were injected with systemic corticosterone. Finally, pups were reared with an abusive mother to determine ecological relevance. RESULTS: Our results suggest that the natural and learned attachment odors indistinguishably control social behavior in infancy (approach to the odor and interactions with the mother). However, with corticosterone injection, pups with an abusive attachment show disrupted infant social behavior with the mother and engagement of the amygdala. CONCLUSIONS: This animal model of attachment accommodates both abusive and typical attachment and suggests that pups' social behavior and underlying neural circuitry may provide clues to understanding attachment in children with various conditions of care.

Asunto(s)

Animales Recién Nacidos , Cuidadores/psicología , Maltrato a los Niños/psicología , Modelos Animales , Apego a Objetos , Amígdala del Cerebelo/efectos de los fármacos , Amígdala del Cerebelo/fisiología , Animales , Condicionamiento Clásico/efectos de los fármacos , Condicionamiento Clásico/fisiología , Corticosterona/sangre , Corticosterona/farmacología , Femenino , Humanos , Lactante , Masculino , Conducta Materna/fisiología , Aprendizaje por Laberinto/efectos de los fármacos , Aprendizaje por Laberinto/fisiología , Odorantes , Bulbo Olfatorio/efectos de los fármacos , Bulbo Olfatorio/fisiología , Ratas , Ratas Long-Evans , Conducta Social , Estrés Psicológico/fisiopatología

RESUMEN

Infant rats require maternal odor learning to guide pups' proximity-seeking of the mother and nursing. Maternal odor learning occurs using a simple learning circuit including robust olfactory bulb norepinephrine (NE), release from the locus ceruleus (LC), and amygdala suppression by low corticosterone (CORT). Early-life stress increases NE but also CORT, and we questioned whether early-life stress disrupted attachment learning and its neural correlates [2-deoxyglucose (2-DG) autoradiography]. Neonatal rats were normally reared or stressed-reared during the first 6 d of life by providing the mother with insufficient bedding for nest building and were odor-0.5 mA shock conditioned at 7 d old. Normally reared paired pups exhibited typical odor approach learning and associated olfactory bulb enhanced 2-DG uptake. However, stressed-reared pups showed odor avoidance learning and both olfactory bulb and amygdala 2-DG uptake enhancement. Furthermore, stressed-reared pups had elevated CORT levels, and systemic CORT antagonist injection reestablished the age-appropriate odor-preference learning, enhanced olfactory bulb, and attenuated amygdala 2-DG. We also assessed the neural mechanism for stressed-reared pups' abnormal behavior in a more controlled environment by injecting normally reared pups with CORT. This was sufficient to produce odor aversion, as well as dual amygdala and olfactory bulb enhanced 2-DG uptake. Moreover, we assessed a unique cascade of neural events for the aberrant effects of stress rearing: the amygdala-LC-olfactory bulb pathway. Intra-amygdala CORT or intra-LC corticotropin releasing hormone (CRH) infusion supported aversion learning with intra-LC CRH infusion associated with increased olfactory bulb NE (microdialysis). These results suggest that early-life stress disturbs attachment behavior via a unique cascade of events (amygdala-LC-olfactory bulb).

Asunto(s)

Amígdala del Cerebelo/fisiología , Corticosterona/fisiología , Hormona Liberadora de Corticotropina/fisiología , Locus Coeruleus/fisiología , Norepinefrina/fisiología , Bulbo Olfatorio/fisiología , Estrés Psicológico/metabolismo , Factores de Edad , Animales , Animales Recién Nacidos , Aprendizaje por Asociación/fisiología , Femenino , Masculino , Conducta Materna/fisiología , Conducta Materna/psicología , Ratas , Ratas Long-Evans , Estrés Psicológico/psicología

RESUMEN

Behavioral transitions characterize development. Young infant rats paradoxically prefer odors that are paired with shock, but older pups learn aversions. This transition is amygdala and corticosterone dependent. Using microarrays and microdialysis, we found downregulated dopaminergic presynaptic function in the amygdala with preference learning. Corticosterone-injected 8-d-old pups and untreated 12-d-old pups learned aversions and had dopaminergic upregulation in the amygdala. Dopamine injection into the amygdala changed preferences to aversions, whereas dopamine antagonism reinstated preference learning.

Asunto(s)

Amígdala del Cerebelo/fisiología , Reacción de Prevención/fisiología , Condicionamiento Clásico/fisiología , Dopamina/metabolismo , Factores de Edad , Amígdala del Cerebelo/efectos de los fármacos , Animales , Animales Recién Nacidos , Reacción de Prevención/efectos de los fármacos , Condicionamiento Clásico/efectos de los fármacos , Corticosterona/sangre , Corticosterona/farmacología , Dopamina/genética , Antagonistas de Dopamina/farmacología , Técnicas Electroquímicas/métodos , Electrochoque/efectos adversos , Femenino , Perfilación de la Expresión Génica/métodos , Regulación del Desarrollo de la Expresión Génica/efectos de los fármacos , Regulación del Desarrollo de la Expresión Génica/fisiología , Masculino , Aprendizaje por Laberinto/efectos de los fármacos , Aprendizaje por Laberinto/fisiología , Microdiálisis/métodos , Odorantes , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Ratas , Ratas Long-Evans

RESUMEN

Early life trauma alters later life emotions, including fear. To better understand mediating mechanisms, we subjected pups to either predictable or unpredictable trauma, in the form of paired or unpaired odor-0.5 mA shock conditioning which, during a sensitive period, produces an odor preference and no learning respectively. Fear conditioning and its neural correlates were then assessed after the sensitive period at postnatal day (PN)13 or in adulthood, ages when amygdala-dependent fear occurs. Our results revealed that paired odor-shock conditioning starting during the sensitive period (PN8-12) blocked fear conditioning in older infants (PN13) and pups continued to express olfactory bulb-dependent odor preference learning. This PN13 fear learning inhibition was also associated with suppression of shock-induced corticosterone, although the age appropriate amygdala-dependent fear learning was reinstated with systemic corticosterone (3 mg/kg) during conditioning. On the other hand, sensitive period odor-shock conditioning did not prevent adult fear conditioning, although freezing, amygdala and hippocampal 2-DG uptake and corticosterone levels were attenuated compared to adult conditioning without infant conditioning. Normal levels of freezing, amygdala and hippocampal 2-DG uptake were induced with systemic corticosterone (5 mg/kg) during adult conditioning. These results suggest that the contingency of early life trauma mediates at least some effects of early life stress through learning and suppression of corticosterone levels. However, developmental differences between infants and adults are expressed with PN13 infants' learning consistent with the original learned preference, while adult conditioning overrides the original learned preference with attenuated amygdala-dependent fear learning.

RESUMEN

BACKGROUND: Early life adverse experience alters adult emotional and cognitive development. Here we assess early life learning about adverse experience and its consequences on adult fear conditioning and amygdala activity. METHODS: Neonatal rats were conditioned daily from 8-12 days-old with paired odor (conditioned stimulus, CS) .5mA shock, unpaired, odor-only, or naive (no infant conditioning). In adulthood, each infant training group was divided into three adult training groups: paired, unpaired or odor-only, using either the same infant CS odor, or a novel adult CS odor without or with the infant CS present as context. Adults were cue tested for freezing (odor in novel environment), with amygdala (14)C 2-DG autoradiography and electrophysiology assessment. RESULTS: Infant paired odor-shock conditioning attenuated adult fear conditioning, but only if the same infant CS odor was used. The (14)C 2-DG activity correlated with infant paired odor-shock conditioning produced attenuated amygdala but heightened olfactory bulb activity. Electrophysiological amygdala assessment further suggests early experience causes changes in amygdala processing as revealed by increased paired-pulse facilitation in adulthood. CONCLUSIONS: This suggests some enduring effects of early life adversity (shock) are under CS control and dependent upon learning for their impact on later adult fear learning.

Asunto(s)

Envejecimiento , Amígdala del Cerebelo/fisiología , Condicionamiento Clásico/fisiología , Miedo , Memoria/fisiología , Odorantes , Amígdala del Cerebelo/diagnóstico por imagen , Análisis de Varianza , Animales , Animales Recién Nacidos , Autorradiografía/métodos , Reacción de Prevención , Conducta Animal , Desoxiglucosa/metabolismo , Estimulación Eléctrica/métodos , Potenciales Evocados/efectos de la radiación , Reacción Cataléptica de Congelación/fisiología , Masculino , Aprendizaje por Laberinto , Bulbo Olfatorio/diagnóstico por imagen , Radiografía , Ratas , Ratas Long-Evans , Tiempo de Reacción/fisiología , Tiempo de Reacción/efectos de la radiación