RESUMEN
Enzymes that regulate histone lysine methylation play important roles in neuronal differentiation, but little is known about their contributions to activity-regulated gene transcription in differentiated neurons. We characterized activity-regulated expression of lysine demethylases and lysine methyltransferases in the hippocampus of adult male mice following pilocarpine-induced seizure. Pilocarpine drove a 20-fold increase in mRNA encoding the histone H3 lysine 27-specific demethylase Kdm6b selectively in granule neurons of the dentate gyrus, and this induction was recapitulated in cultured hippocampal neurons by bicuculline and 4-aminopyridine (Bic + 4AP) stimulation of synaptic activity. Because activity-regulated gene expression is highly correlated with neuronal survival, we tested the requirement for Kdm6b expression in Bic + 4AP induced preconditioning of neuronal survival. Prior exposure to Bic + 4AP promoted neuronal survival in control neurons upon growth factor withdrawal; however, this effect was ablated when we knocked down Kdm6b expression. Loss of Kdm6b did not disrupt activity-induced expression of most genes, including that of a gene set previously established to promote neuronal survival in this assay. However, using bioinformatic analysis of RNA sequencing data, we discovered that Kdm6b knockdown neurons showed impaired inducibility of a discrete set of genes annotated for their function in inflammation. These data reveal a novel function for Kdm6b in activity-regulated neuronal survival, and they suggest that activity- and Kdm6b-dependent regulation of inflammatory gene pathways may serve as an adaptive pro-survival response to increased neuronal activity.
Asunto(s)
Hipocampo/patología , Histona Demetilasas con Dominio de Jumonji/metabolismo , Neuronas/metabolismo , Convulsiones/patología , 4-Aminopiridina/farmacología , Animales , Astrocitos/efectos de los fármacos , Astrocitos/metabolismo , Bicuculina/farmacología , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/genética , Células Cultivadas , Modelos Animales de Enfermedad , Antagonistas de Receptores de GABA-A/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Hipocampo/efectos de los fármacos , Histona Demetilasas con Dominio de Jumonji/genética , Masculino , Ratones , Ratones Endogámicos C57BL , Agonistas Muscarínicos/toxicidad , Neuronas/efectos de los fármacos , Pilocarpina/toxicidad , Bloqueadores de los Canales de Potasio/farmacología , Interferencia de ARN/fisiología , Convulsiones/inducido químicamenteRESUMEN
Loss-of-function mutations in the methyl-DNA binding protein MeCP2 are associated with neurological dysfunction and impaired neural plasticity. However, the transcriptional changes that underlie these deficits remain poorly understood. Here, we show that mice bearing a C-terminal truncating mutation in Mecp2 (Mecp2 ( 308) ) are hypersensitive to the locomotor stimulating effects of cocaine. Furthermore, these mice have gene-specific alterations in striatal immediate-early gene (IEG) induction following cocaine administration. MeCP2 mutant mice show normal levels of baseline and cocaine-induced striatal Fos expression compared with their wild-type littermates. However, the mutant mice have enhanced cocaine-induced transcription of Junb and Arc. At the chromatin level, we find increased histone H3 acetylation at gene promoters in the Mecp2 mutant mice compared with their wild-type littermates, whereas two sites of repressive histone methylation are unchanged. Interestingly, we find that MeCP2 mutant mice show increased steady-state association of elongation-competent RNA Polymerase II (RNAP II) with the Junb and Arc promoters, whereas levels of RNAP II association at the Fos promoter are unchanged. These data reveal a gene-specific effect of MeCP2 on the recruitment of RNAP II to gene promoters that may modulate the inducibility of IEGs. In addition, our findings raise the possibility that aberrant regulation of IEGs including Junb and Arc may contribute to altered cocaine-induced neuronal and behavioral plasticity in Mecp2 mutant mice.
Asunto(s)
Regulación de la Expresión Génica , Genes Inmediatos-Precoces/genética , Proteína 2 de Unión a Metil-CpG/genética , Mutación/genética , Transcripción Genética , Acetilación/efectos de los fármacos , Animales , Cocaína/administración & dosificación , Cocaína/farmacología , Proteínas del Citoesqueleto/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Histonas/metabolismo , Locomoción/efectos de los fármacos , Proteína 2 de Unión a Metil-CpG/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Mutantes , Proteínas del Tejido Nervioso/metabolismo , Regiones Promotoras Genéticas/genética , Unión Proteica/efectos de los fármacos , Proteínas Proto-Oncogénicas c-fos/metabolismo , Proteínas Proto-Oncogénicas c-jun/metabolismo , ARN Polimerasa II/metabolismo , Transcripción Genética/efectos de los fármacosRESUMEN
Like other recreational drugs, cannabinoids may produce different effects in men and women. In this study we measured the effects of delta9-tetrahydrocannabinol (THC) on spatial learning in two groups that are underrepresented in drug research--females and adolescents. In the first experiment, adolescent (postnatal day 30) and adult (postnatal day 70) rats of both sexes were treated subchronically with 5.0 mg/kg THC or vehicle for five consecutive days. Thirty minutes after each daily injection, they were tested on the spatial version of the Morris water maze task. In the second experiment, a separate group of adolescent and adult rats of both sexes was treated with 5.0 mg/kg THC or vehicle daily for 21 days and tested, 4 weeks later, on the spatial version of the water maze. Subchronic THC impaired spatial learning, and this effect was dependent upon both the age and sex of the animals tested. Prior exposure to chronic THC, however, did not cause any long-lasting spatial learning deficits. On the basis of our previous studies in male rats the third experiment assessed the dose-response relationship for the effects of THC on spatial learning and memory in female animals. We found that subchronic THC treatment (2.5, 5.0, or 10.0 mg/kg, intraperitoneally) disrupted learning in both adolescents and adults, but with greater effects at higher doses in adolescents compared with adults. The developmental sensitivity to subchronic THC confirms previous work carried out in our laboratory, and the sex-dependent effects highlight the importance of including females in drug abuse and addiction research.
Asunto(s)
Dronabinol/toxicidad , Aprendizaje por Laberinto/efectos de los fármacos , Psicotrópicos/toxicidad , Conducta Espacial/efectos de los fármacos , Factores de Edad , Animales , Relación Dosis-Respuesta a Droga , Dronabinol/administración & dosificación , Femenino , Inyecciones Intraperitoneales , Masculino , Memoria/efectos de los fármacos , Psicotrópicos/administración & dosificación , Distribución Aleatoria , Ratas , Ratas Sprague-Dawley , Factores SexualesRESUMEN
RATIONALE: Unpleasant side effects of drugs of abuse often limit their repeated use; however, such effects may be attenuated in adolescents compared to adults. OBJECTIVES: We investigated whether the anxiogenic, aversive, or locomotor effects of delta-9-tetrahydrocannabinol (THC) differ between adolescent and adult rats. METHODS: We used the elevated plus maze (EPM) and light-dark tests of anxiety, the conditioned taste aversion and conditioned place aversion (CPA) tests of generalized aversion, and measures of stress hormone levels in serum to examine effects of THC in adolescent and adult rats. Locomotor activity was also recorded in the EPM, light-dark task, and CPA association sessions. RESULTS: In the EPM and light-dark tasks, THC was anxiogenic in both age groups, but the drug was more anxiogenic in adults than in adolescents. In the place and taste aversion tasks, THC was aversive in both ages, and at 1.25 and 5 mg/kg, was more aversive in adults than in adolescents. The locomotor response to THC, as measured in the anxiety tasks and CPA, affected adults more than adolescents. Multiple measures revealed a locomotor-decreasing effect in adults, whereas some measures suggested a small locomotor-increasing effect in adolescent rats. CONCLUSIONS: These results suggest that THC can have greater anxiogenic, aversive, and locomotor-reducing effects in adult rats than in adolescent rats. These findings suggest an explanation for reduced marijuana use in adult humans compared to teenagers.
Asunto(s)
Envejecimiento , Ansiedad , Reacción de Prevención/efectos de los fármacos , Conducta Animal/efectos de los fármacos , Dronabinol/farmacología , Alucinógenos/farmacología , Actividad Motora/efectos de los fármacos , Psicotrópicos/farmacología , Hormona Adrenocorticotrópica/sangre , Factores de Edad , Animales , Condicionamiento Psicológico/efectos de los fármacos , Corticosterona/sangre , Relación Dosis-Respuesta a Droga , Masculino , Ratas , Gusto , Factores de TiempoRESUMEN
Marijuana use remains strikingly high among young users in the U.S., and yet few studies have assessed the effects of delta9-tetrahydrocannabinol (THC) in adolescents compared to adults. This study measured the effects of THC on male adolescent and adult rats in the Morris water maze. In Experiment 1, adolescent (PD=30-32) and adult (PD=65-70) rats were treated acutely with 5.0 mg/kg THC or vehicle while trained on the spatial version of the water maze on five consecutive days. In Experiment 2, adolescent and adult rats were treated acutely with 2.5 or 10.0 mg/kg THC or vehicle while trained on either the spatial and non-spatial versions of the water maze. In Experiment 3, adolescent and adult rats were treated with 5.0 mg/kg THC or vehicle daily for 21 days, and were trained on the spatial and then the non-spatial versions of the water maze task four weeks later in the absence of THC. THC impaired both spatial and nonspatial learning more in adolescents than in adults at all doses tested. However, there were no long-lasting significant effects on either spatial or non-spatial learning in rats that had been previously exposed to THC for 21 days. This developmental sensitivity is analogous to the effects of ethanol, another commonly used recreational drug.
Asunto(s)
Dronabinol/toxicidad , Aprendizaje/efectos de los fármacos , Adolescente , Adulto , Factores de Edad , Animales , Dronabinol/administración & dosificación , Humanos , Masculino , Aprendizaje por Laberinto/efectos de los fármacos , Memoria/efectos de los fármacos , Modelos Animales , Psicotrópicos/administración & dosificación , Psicotrópicos/toxicidad , Ratas , Ratas Sprague-DawleyRESUMEN
BACKGROUND: Women consume less alcohol than men, and yet they are more susceptible than men to the negative medical consequences of alcohol use, such as cirrhosis of the liver, cardiac disease, and cognitive impairments. This sex difference is also reflected in animal studies, in which male and female rats differ on both behavioral and electrophysiological measures. Given that one significant difference between males and females is the cycling fluctuations of the sex hormones, this study aimed to compare the relative sensitivity of adolescent and adult rats of both sexes and varying estrous stages to the behavioral and electrophysiological effects of ethanol. METHODS: Adult female rats were lavaged daily for estrous cycle assessment. Following administration of 5 g/kg ethanol, adolescent and adult male and female animals were observed for loss of the righting reflex. Then, using whole-cell recording, we tested the response of spontaneous, gamma-aminobutyric acid (GABA(A)) receptor-mediated inhibitory postsynaptic currents (sIPSCs) in hippocampal slices from drug-naïve adult male and female rats. RESULTS: Consistent with previous findings, adolescent animals were less sensitive than adults to the effect of ethanol on the righting reflex. In addition, adult proestrous and diestrous female rats were less sensitive than male rats to the sedative effects of ethanol. Finally, ethanol increased the frequency of sIPSCs in hippocampal pyramidal neurons and did so more potently in cells from male rats than in those from female rats. CONCLUSIONS: Female animals are less sensitive to the behavioral sedative effects of ethanol than adult male rats, and the effect is pronounced in the proestrous and diestrous states. This sex difference may be related to differential sensitivity of GABA receptor-mediated central nervous system function to ethanol in females.
Asunto(s)
Nivel de Alerta/efectos de los fármacos , Estro/efectos de los fármacos , Etanol/farmacología , GABAérgicos/farmacología , Hipocampo/efectos de los fármacos , Hipnóticos y Sedantes/farmacología , Potenciales de la Membrana/efectos de los fármacos , Equilibrio Postural/efectos de los fármacos , Reflejo/efectos de los fármacos , Factores de Edad , Animales , Femenino , Masculino , Ratas , Ratas Sprague-Dawley , Receptores de GABA-A/efectos de los fármacos , Factores SexualesRESUMEN
Using mu-opioid receptor knockout (MKO) mice, we examined ethanol-induced FOS immunoreactivity (FOSir) in the brain as an indicator of neuronal activation to assess the role of the mu-opioid receptor in modulating ethanol's actions in the central nervous system (CNS). Saline stimulated FOSir in the paraventricular thalamic nucleus (PVA) and the dorsal hypothalamic area (DA) in MKO mice, but not in wild-type (WT), suggesting that MKO homozygotes may differ responsively from WT. Treatment with ethanol (4 g/kg, i.p.) induced FOSir in the PVA, DA, supraoptic (SO), paraventricular hypothalamic (PVN), lateral parabrachial (LPB), locus coeruleus (LC) and Edinger-Westphal (EW) nuclei in both MKO and WT mice. However, ethanol stimulated modest FOSir in the lateral septal division (LSV), suprachiasmatic nucleus (SCh) and the dorsal and ventral lateral geniculate nuclei (DLG and VLG) in WT mice, but not in MKO mice. In contrast, higher levels of ethanol-induced FOSir were observed in the ventral pallidum (VP) and globus pallidus (GP) of MKO mice as compared to WT. These data suggest that ethanol continues to activate several brain regions, even without the mu-opioid receptor pathway. However, the mu-opioid receptor may be significant in mediating ethanol's effects in some restricted areas of the brain.