RESUMO
BACKGROUND: Toxicological studies evaluating the possible harmful effects of pesticides on bees are important and allow the emergence of protection and pollinator conservation strategies. This study aimed to evaluate the effects of exposure to a sublethal concentration of imidacloprid (LC50/100 : 0.014651 ng imidacloprid µL-1 diet) on the distribution of certain proteins identified in the brain of Apis mellifera worker bees using a MALDI-imaging approach. This technique enables proteomic analysis of tissues in situ by monitoring the spatiotemporal dynamics of the biochemical processes occurring at a specific time in specific brain neuropils. For this purpose, foraging bees were exposed to an 8-day diet containing a sublethal concentration of imidacloprid corresponding to the LC50/100 . Bees were collected on day 8 of exposure, and their brains analyzed using protein density maps. RESULTS: The results showed that exposure to imidacloprid led to a series of biochemical changes, including alterations in synapse regulation, apoptosis regulation and oxidative stress, which may adversely impair the physiology of these colony bees. CONCLUSION: Worker bee contact with even tiny amounts of imidacloprid had potent effects leading to the overexpression of a series of proteins related to important cellular processes that were possibly damaged by the insecticide. © 2018 Society of Chemical Industry.
Assuntos
Encéfalo/efeitos dos fármacos , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , Animais , Apoptose , Abelhas , Feminino , Proteínas de Insetos/metabolismo , Neurópilo/efeitos dos fármacos , Neurópilo/metabolismo , Estresse Oxidativo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Sinapses/efeitos dos fármacosRESUMO
The medial nucleus of the amygdala (MeA) is a complex component of the "extended amygdala" in rats. Its posterodorsal subnucleus (MePD) has a remarkable expression of gonadal hormone receptors, is sexually dimorphic or affected by sex steroids, and modulates various social behaviors. Dendritic spines show remarkable changes relevant for synaptic strength and plasticity. Adult males have more spines than females, the density of dendritic spines changes in the course of hours to a few days and is lower in proestrous and estrous phases of the ovarian cycle, or is affected by both sex steroid withdrawal and hormonal replacement therapy in the MePD. Males also have more thin spines than mushroom-like or stubby/wide ones. The presence of dendritic fillopodia and axonal protrusions in the MePD neuropil of adult animals reinforces the evidence for local plasticity. Estrogen affects synaptic and cellular growth and neuroprotection in the MeA by regulating the activity of the cyclic AMP response element-binding protein (CREB)-related gene products, brain-derived neurotrophic factor (BDNF), the anti-apoptotic protein B-cell lymphoma-2 (Bcl-2) and the activity-regulated cytoskeleton-related protein (Arc). These effects on signal transduction cascades can also lead to local protein synthesis and/or rearrangement of the cytoskeleton and subsequent numerical/morphological alterations in dendritic spines. Various working hypotheses are raised from these experimental data and reveal the MePD as a relevant region to study the effects of sex steroids in the rat brain.
Assuntos
Tonsila do Cerebelo/patologia , Espinhas Dendríticas/patologia , Hormônios Esteroides Gonadais/farmacologia , Neurônios/patologia , Tonsila do Cerebelo/efeitos dos fármacos , Animais , Axônios/efeitos dos fármacos , Axônios/patologia , Biomarcadores/metabolismo , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Proliferação de Células/efeitos dos fármacos , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Proteínas do Citoesqueleto/metabolismo , Citoesqueleto/efeitos dos fármacos , Citoesqueleto/ultraestrutura , Espinhas Dendríticas/efeitos dos fármacos , Espinhas Dendríticas/ultraestrutura , Ciclo Estral , Feminino , Masculino , Proteínas do Tecido Nervoso/metabolismo , Neurônios/efeitos dos fármacos , Neurópilo/efeitos dos fármacos , Neurópilo/patologia , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Ratos , Fatores Sexuais , Transdução de SinaisRESUMO
Serotonin is a conspicuous neuromodulator in the nervous system of many vertebrates and invertebrates. In previous experiments performed in the leech nervous system, we compared the effect of the amine released from endogenous sources [using selective serotonin reuptake inhibitors (SSRIs), e.g. fluoxetine] with that of bath-applied serotonin. The results suggested that the amine does not reach all its targets in a uniform way, but produces the activation of an interneuronal pathway that generated specific synaptic responses on different neurons. Taking into account that the release of the amine is often regulated at the presynaptic level, we have investigated whether autoreceptor antagonists mimic the SSRIs effect. We found that methiothepin (100 microM) produced similar effects than fluoxetine. To further test the hypothesis that endogenous serotonin produce its effect by acting locally at specific sites, we analyzed the effect of iontophoretic applications of serotonin. We found a site in the neuropil of the leech ganglia where serotonin application mimicked the effect of the SSRIs and the 5-HT antagonist. The results further support the view that the effect of serotonin exhibits a spatial specificity that can be relevant to understand its modulatory actions.
Assuntos
Gânglios dos Invertebrados/fisiologia , Sanguessugas/fisiologia , Serotonina/fisiologia , Animais , Ciproeptadina/farmacologia , Interpretação Estatística de Dados , Eletrofisiologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Fluoxetina/farmacologia , Gânglios dos Invertebrados/anatomia & histologia , Gânglios dos Invertebrados/efeitos dos fármacos , Iontoforese , Metiotepina/farmacologia , Neurônios Motores/efeitos dos fármacos , Vias Neurais/efeitos dos fármacos , Neurópilo/efeitos dos fármacos , Serotonina/farmacologia , Antagonistas da Serotonina/farmacologia , Inibidores Seletivos de Recaptação de Serotonina/farmacologiaRESUMO
In the present study, we investigated the effects of mercury intoxication on the structure of the posteromedial barrel subfield (PMBSF) in the primary somatosensory cortex (SI) of adult rats, as revealed by histochemical reactivity to the enzyme NADPH diaphorase (NADPH-d). Enzymatic reactivity in the neuropil inside barrels was drastically reduced in intoxicated animals, suggesting that the synthesis and/or transport of the nitric oxide synthase enzyme can be altered in acute mercury intoxication. However, the cell bodies and dendrites of barrel neurons, also strongly reactive to the enzyme, were spared from the mercury's deleterious effects.
Assuntos
Compostos de Metilmercúrio/toxicidade , NADPH Desidrogenase/metabolismo , Córtex Somatossensorial/efeitos dos fármacos , Animais , Densitometria , Histocitoquímica , Masculino , Compostos de Metilmercúrio/farmacocinética , Neurópilo/efeitos dos fármacos , Neurópilo/enzimologia , Óxido Nítrico Sintase Tipo I/biossíntese , Consumo de Oxigênio/efeitos dos fármacos , Ratos , Ratos WistarRESUMO
The medial amygdala (MeA) has receptors for gonadal hormones and is a sexually dimorphic area in rats. The aims of the present work were (1) to look at sex differences and the effect of gonadal hormone withdrawal in males castrated as offspring or at adulthood on neuronal soma area in the anterior and posterior MeA and (2) to study the dendritic branching and the density of dendritic spines in neurons from the MeA of intact males and females. Animals were adult rats, for which the single-section Golgi method was used. Stellate and bitufted cells were found in the MeA. Comparing data among groups, no significant difference in cell body area was found. Dendrites divide sparingly and have very different lengths, and a statistical difference (p < 0.001, males higher than females) in the spine density in the anterior MeA, but not in the posterior MeA, was found. These results suggest that castration does not alter the somal area in males submitted to gonadectomy during the early postnatal period or at adulthood. In addition, the already described sex difference in this nucleus may be more related to the neuropil than the neuronal somal area, which may be relevant for the function of the MeA.
Assuntos
Tonsila do Cerebelo/citologia , Hormônios Esteroides Gonadais/farmacologia , Neurônios/efeitos dos fármacos , Neurônios/ultraestrutura , Tonsila do Cerebelo/efeitos dos fármacos , Tonsila do Cerebelo/ultraestrutura , Animais , Corantes , Dendritos/efeitos dos fármacos , Dendritos/ultraestrutura , Feminino , Masculino , Neurópilo/efeitos dos fármacos , Neurópilo/ultraestrutura , Orquiectomia , Ovariectomia , Ratos , Ratos WistarAssuntos
Diazepam/toxicidade , Troca Materno-Fetal/efeitos dos fármacos , Mesencéfalo/efeitos dos fármacos , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Neurópilo/efeitos dos fármacos , Animais , Feminino , Colículos Inferiores/efeitos dos fármacos , Camundongos , Atividade Motora/efeitos dos fármacos , Gravidez , Núcleo Rubro/efeitos dos fármacos , Colículos Superiores/efeitos dos fármacos , Fatores de TempoRESUMO
The effects of methylmercury (MeHg) on histochemical demonstration of the NADPH-diaphorase (NADPH-d) activity in the striate cortex were studied in 4 adult cats. Two animals were used as control. The contaminated animals received 50 ml milk containing 0.42 µg MeHg and 100 g fish containing 0.03 µg MeHg daily for 2 months. The level of MeHg in area 17 of intoxicated animals was 3.2 µg/g wet weight brain tissue. Two cats were perfused 24 h after the last dose (group 1) and the other animals were perfused 6 months later (group 2). After microtomy, sections were processed for NADPHd histochemistry procedures using the malic enzyme method. Dendritic branch counts were performed from camera lucida drawings for control and intoxicated animals (N = 80). Average, standard deviation and Student t-test were calculated for each data group. The concentrations of mercury (Hg) in milk, fish and brain tissue were measured by acid digestion of samples, followed by reduction of total Hg in the digested sample to metallic Hg using stannous chloride followed by atomic fluorescence analysis. Only group 2 revealed a reduction of the neuropil enzyme activity and morphometric analysis showed a reduction in dendritic field area and in the number of distal dendrite branches of the NADPHd neurons in the white matter (P<0.05). These results suggest that NADPHd neurons in the white matter are more vulnerable to the long-term effects of MeHg than NADPHd neurons in the gray matter.
Assuntos
Gatos , Animais , Compostos de Metilmercúrio/intoxicação , NADPH Desidrogenase/metabolismo , Neurópilo/enzimologia , Córtex Visual/efeitos dos fármacos , Córtex Visual/enzimologia , Fluorescência , Mercúrio/análise , Microtomia , Neurônios/efeitos dos fármacos , Neurônios/patologia , Neurópilo/efeitos dos fármacos , Neurópilo/patologia , Córtex Visual/patologiaRESUMO
The effects of methylmercury (MeHg) on histochemical demonstration of the NADPH-diaphorase (NADPH-d) activity in the striate cortex were studied in 4 adult cats. Two animals were used as control. The contaminated animals received 50 ml milk containing 0.42 microgram MeHg and 100 g fish containing 0.03 microgram MeHg daily for 2 months. The level of MeHg in area 17 of intoxicated animals was 3.2 micrograms/g wet weight brain tissue. Two cats were perfused 24 h after the last dose (group 1) and the other animals were perfused 6 months later (group 2). After microtomy, sections were processed for NADPHd histochemistry procedures using the malic enzyme method. Dendritic branch counts were performed from camera lucida drawings for control and intoxicated animals (N = 80). Average, standard deviation and Student t-test were calculated for each data group. The concentrations of mercury (Hg) in milk, fish and brain tissue were measured by acid digestion of samples, followed by reduction of total Hg in the digested sample to metallic Hg using stannous chloride followed by atomic fluorescence analysis. Only group 2 revealed a reduction of the neuropil enzyme activity and morphometric analysis showed a reduction in dendritic field area and in the number of distal dendrite branches of the NADPHd neurons in the white matter (P < 0.05). These results suggest that NADPHd neurons in the white matter are more vulnerable to the long-term effects of MeHg than NADPHd neurons in the gray matter.