RESUMO
Fentanyl is a powerful painkiller that elicits euphoria and positive reinforcement1. Fentanyl also leads to dependence, defined by the aversive withdrawal syndrome, which fuels negative reinforcement2,3 (that is, individuals retake the drug to avoid withdrawal). Positive and negative reinforcement maintain opioid consumption, which leads to addiction in one-fourth of users, the largest fraction for all addictive drugs4. Among the opioid receptors, µ-opioid receptors have a key role5, yet the induction loci of circuit adaptations that eventually lead to addiction remain unknown. Here we injected mice with fentanyl to acutely inhibit γ-aminobutyric acid-expressing neurons in the ventral tegmental area (VTA), causing disinhibition of dopamine neurons, which eventually increased dopamine in the nucleus accumbens. Knockdown of µ-opioid receptors in VTA abolished dopamine transients and positive reinforcement, but withdrawal remained unchanged. We identified neurons expressing µ-opioid receptors in the central amygdala (CeA) whose activity was enhanced during withdrawal. Knockdown of µ-opioid receptors in CeA eliminated aversive symptoms, suggesting that they mediate negative reinforcement. Thus, optogenetic stimulation caused place aversion, and mice readily learned to press a lever to pause optogenetic stimulation of CeA neurons that express µ-opioid receptors. Our study parses the neuronal populations that trigger positive and negative reinforcement in VTA and CeA, respectively. We lay out the circuit organization to develop interventions for reducing fentanyl addiction and facilitating rehabilitation.
Assuntos
Fentanila , Receptores Opioides mu , Reforço Psicológico , Animais , Feminino , Masculino , Camundongos , Analgésicos Opioides/farmacologia , Analgésicos Opioides/administração & dosagem , Núcleo Central da Amígdala/citologia , Núcleo Central da Amígdala/efeitos dos fármacos , Núcleo Central da Amígdala/metabolismo , Dopamina/metabolismo , Neurônios Dopaminérgicos/efeitos dos fármacos , Neurônios Dopaminérgicos/metabolismo , Fentanila/farmacologia , Camundongos Endogâmicos C57BL , Núcleo Accumbens/citologia , Núcleo Accumbens/efeitos dos fármacos , Núcleo Accumbens/metabolismo , Transtornos Relacionados ao Uso de Opioides/metabolismo , Transtornos Relacionados ao Uso de Opioides/patologia , Optogenética , Receptores Opioides mu/metabolismo , Síndrome de Abstinência a Substâncias/metabolismo , Síndrome de Abstinência a Substâncias/patologia , Área Tegmentar Ventral/citologia , Área Tegmentar Ventral/efeitos dos fármacos , Área Tegmentar Ventral/metabolismoRESUMO
Our previous studies found that the central amygdala (CeA) modulates cerebellum-dependent eyeblink conditioning (EBC) using muscimol inactivation. We also found that CeA inactivation decreases cerebellar neuronal activity during the conditional stimulus (CS) from the start of training. Based on these findings, we hypothesized that the CeA facilitates CS input to the cerebellum. The current study tested the CS facilitation hypothesis using optogenetic inhibition with archaerhodopsin (Arch) and excitation with channelrhodopsin (ChR2) of the CeA during EBC in male rats. Optogenetic manipulations were administered during the 400 ms tone CS or during a 400 ms pre-CS period. As predicted by the CS facilitation hypothesis CeA inhibition during the CS impaired EBC and CeA excitation during the CS facilitated EBC. Unexpectedly, CeA inhibition just prior to the CS also impaired EBC, while CeA excitation during the pre-CS pathway did not facilitate EBC. The results suggest that the CeA contributes to CS facilitation and vigilance during the pre-CS period. These putative functions of the CeA may be mediated through separate output pathways from the CeA to the cerebellum.
Assuntos
Núcleo Central da Amígdala , Cerebelo , Condicionamento Palpebral , Optogenética , Animais , Masculino , Cerebelo/fisiologia , Cerebelo/efeitos dos fármacos , Núcleo Central da Amígdala/fisiologia , Núcleo Central da Amígdala/efeitos dos fármacos , Condicionamento Palpebral/fisiologia , Condicionamento Palpebral/efeitos dos fármacos , Ratos , Ratos Long-Evans , Condicionamento Clássico/fisiologia , Condicionamento Clássico/efeitos dos fármacosRESUMO
The central nucleus of the amygdala is known to play key roles in alcohol use and affect. Neurotensin neurons in the central nucleus of the amygdala have been shown to regulate alcohol drinking in male mice. However, little is known about which neurotransmitters released by these cells drive alcohol consumption or whether these cells drive alcohol consumption in female mice. Here we show that knockdown of GABA release from central amygdala neurotensin neurons using a Nts-cre-dependent vGAT-shRNA-based AAV strategy reduces alcohol drinking in male, but not female, mice. This manipulation did not impact avoidance behavior, except in a fasted novelty-suppressed feeding test, in which vGAT shRNA mice demonstrated increased latency to feed on a familiar high-value food reward, an effect driven by male mice. In contrast, vGAT shRNA female mice showed heightened sensitivity to thermal stimulation. These data show a role for GABA release from central amygdala neurotensin neurons in modulating consumption of rewarding substances in different motivational states.
Assuntos
Consumo de Bebidas Alcoólicas , Núcleo Central da Amígdala , Neurônios , Neurotensina , Ácido gama-Aminobutírico , Animais , Feminino , Masculino , Núcleo Central da Amígdala/metabolismo , Núcleo Central da Amígdala/efeitos dos fármacos , Neurotensina/metabolismo , Ácido gama-Aminobutírico/metabolismo , Neurônios/metabolismo , Neurônios/efeitos dos fármacos , Consumo de Bebidas Alcoólicas/metabolismo , Consumo de Bebidas Alcoólicas/genética , Camundongos , Camundongos Endogâmicos C57BL , Caracteres Sexuais , Etanol/administração & dosagem , Etanol/farmacologia , Proteínas Vesiculares de Transporte de Aminoácidos InibidoresRESUMO
Alcohol use and anxiety disorders occur in both males and females, but despite sharing similar presentation and classical symptoms, the prevalence of alcohol use disorder (AUD) is lower in females. While anxiety is a symptom and comorbidity shared by both sexes, the common underlying mechanism that leads to AUD and the subsequent development of anxiety is still understudied. Using a rodent model of adolescent intermittent ethanol (AIE) exposure in both sexes, we investigated the epigenetic mechanism mediated by enhancer of zeste 2 (EZH2), a histone methyltransferase, in regulating both the expression of activity-regulated cytoskeleton-associated protein (Arc) and an anxiety-like phenotype in adulthood. Here, we report that EZH2 protein levels were significantly higher in PKC-δ positive GABAergic neurons in the central nucleus of amygdala (CeA) of adult male and female rats after AIE. Reducing protein and mRNA levels of EZH2 using siRNA infusion in the CeA prevented AIE-induced anxiety-like behavior, increased H3K27me3, decreased H3K27ac at the Arc synaptic activity response element (SARE) site, and restored deficits in Arc mRNA and protein expression in both male and female adult rats. Our data indicate that an EZH2-mediated epigenetic mechanism in the CeA plays an important role in regulating anxiety-like behavior and Arc expression after AIE in both male and female rats in adulthood. This study suggests that EZH2 may serve as a tractable drug target for the treatment of adult psychopathology after adolescent alcohol exposure.
Assuntos
Ansiedade , Núcleo Central da Amígdala , Proteína Potenciadora do Homólogo 2 de Zeste , Epigênese Genética , Etanol , Animais , Masculino , Feminino , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Núcleo Central da Amígdala/metabolismo , Núcleo Central da Amígdala/efeitos dos fármacos , Ratos , Ansiedade/metabolismo , Ansiedade/genética , Etanol/farmacologia , Modelos Animais de Doenças , Alcoolismo/genética , Alcoolismo/metabolismo , Neurônios GABAérgicos/metabolismo , Neurônios GABAérgicos/efeitos dos fármacos , Ratos Sprague-Dawley , Proteínas do Citoesqueleto/genética , Proteínas do Citoesqueleto/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismoRESUMO
OBJECTIVE: In Japan, intravenous injection of a 7 % solution of sodium bicarbonate (NaHCO3) had been originally developed to inhibit motion sickness and then have long been used to treat vertigo. Previously, we reported that Fos-positive neurons appear in the amygdala after hypergravity stimulation in rats. In the present study, we examined whether injection of 7 % NaHCO3 inhibits hypergravity-induced Fos expression in the neurons in the central nucleus of the amygdala in rats. METHODS: Rats were exposed to 2 G hypergravity in an animal centrifuge device for 3 h. A solution of 7 % NaHCO3 at a dose of 4 mM/kg was injected intraperitoneally before 2 G hypergraviy. Fos-positive neurons in the amygdala were stained immunohistochemically. RESULTS: The number of Fos-positive neurons in the central nucleus of the amygdala was significantly increased after 2 G hypergravity in rats that received no drugs or saline, compared to that in rats exposed only to the noise of the centrifuge and received 7 % NaHCO3 solution. The number of Fos-positive neurons in the central nucleus of the amygdala after 2 G hypergravity was significantly decreased in rats that received 7 % NaHCO3 solution, compared to that in rats that received no drugs or saline. CONCLUSION: Since Fos expression is a marker of activated neurons, the present findings suggest that hypergravity activates the amygdala and that administration of 7 % NaHCO3 suppresses hypergravity-induced activation of the amygdala. Hypergravity disturbs spatial orientation to produce motion sickness and the amygdala is involved in fear response. Recently, Ziemann et al. suggested that fear-evoking stimuli reduce the pH in the amygdala to activate it, leading to induction of fear behavior and that administering HCO3- attenuates fear behavior [Cell 2009; 139: 1012-1021]. Therefore, it is possible that hypergravity reduces the pH in the amygdala to activate it, thereby inducing the fear associated with motion sickness and that administration of 7 % NaHCO3 increases the brain pH thereby suppressing hypergravity-induced activation of the amygdala and inhibiting the fear associated with motion sickness. In patients with vertigo, 7 % NaHCO3 therapy may increase the brain pH thereby suppressing the activation of the amygdala and inhibiting the fear associated with vertigo to elicit a beneficial clinical effect.
Assuntos
Hipergravidade , Neurônios , Bicarbonato de Sódio , Vertigem , Animais , Ratos , Masculino , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Bicarbonato de Sódio/farmacologia , Tonsila do Cerebelo/metabolismo , Tonsila do Cerebelo/efeitos dos fármacos , Núcleo Central da Amígdala/efeitos dos fármacos , Núcleo Central da Amígdala/metabolismo , Ratos Wistar , Proteínas Proto-Oncogênicas c-fos/metabolismo , Imuno-Histoquímica , CentrifugaçãoRESUMO
Chronic restraint stress induces cognitive abnormalities through changes in synapses and oxidant levels in the amygdala and hippocampus. Given the neuroprotective effects of fruit of Terminalia chebula (Halileh) in different experimental models, the present investigation aimed to address whether Terminalia chebula is able to reduce chronic restraint stress-induced behavioral, synaptic and oxidant markers in the rat model. Thirty-two male Wistar rats were randomly divided into four groups as follows: control (did not receive any treatment and were not exposed to stress), stress (restraint stress for 2â¯h a day for 14 consecutive days), Terminalia chebula (received 200â¯mg/kg hydroalcoholic extract of Terminalia chebula), and stress + Terminalia chebula groups (received 200â¯mg/kg extract of Terminalia chebula twenty minutes before stress) (n = 8 in each group). We used the shuttle box test to assess learning and memory, Golgi-Cox staining to examine dendritic spine density in the dentate gyrus region of the hippocampus and the basolateral and central nuclei of the amygdala, and total antioxidant capacity (TAC) and total oxidant status (TOS) in the brain. The shuttle box test results demonstrated that Terminalia chebula treatment had a profound positive effect on memory parameters, including step-through latency (STL) and time spent in the dark room, when compared to the stress group. Daily oral treatment with Terminalia chebula effectively suppressed the loss of neural spine density in the dentate gyrus region of the hippocampus and the basolateral and central nuclei of the amygdala caused by chronic restraint stress, as demonstrated by Golgi-Cox staining. Additionally, the results indicate that Terminalia chebula significantly reduced the TOS and increased TAC in the brain compared to the stress group. In conclusion, our results suggest that Terminalia chebula improved memory impairment and synaptic loss in the dentate gyrus of the hippocampus and the basolateral and central nuclei of the amygdala induced by restraint stress via inhibiting oxidative damage.
Assuntos
Giro Denteado , Transtornos da Memória , Estresse Oxidativo , Extratos Vegetais , Ratos Wistar , Restrição Física , Estresse Psicológico , Terminalia , Animais , Terminalia/química , Masculino , Estresse Psicológico/metabolismo , Ratos , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/fisiologia , Giro Denteado/metabolismo , Extratos Vegetais/farmacologia , Sinapses/efeitos dos fármacos , Sinapses/metabolismo , Sinapses/patologia , Hipocampo/metabolismo , Hipocampo/patologia , Hipocampo/efeitos dos fármacos , Complexo Nuclear Basolateral da Amígdala/metabolismo , Complexo Nuclear Basolateral da Amígdala/efeitos dos fármacos , Núcleo Central da Amígdala/metabolismo , Núcleo Central da Amígdala/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Espinhas Dendríticas/efeitos dos fármacos , Tonsila do Cerebelo/metabolismoRESUMO
Binge alcohol drinking during adolescence has been associated with neurotoxicity and increased risk for the development of alcohol use disorders. There is evidence that acute and chronic ethanol administration alters c-fos expression, an indirect index of cellular activity, in different brain regions in adult rats. We evaluate here if a binge-like pattern of ethanol exposure during adolescence has a relevant impact on basal and/or ethanol-stimulated regional c-fos activity during adulthood. For that aim, Sprague-Dawley rats PND 25 were saline pre-treated, (SP group) or binge-ethanol pre-treated (BEP group) for twoconsecutive days, at 48-h intervals, over a 14-day period (PND 25 to PND 38). At adult stage (PND 63) and following 25 ethanol-free days, we evaluated c-fos immunoreactivity in response to saline or acute ethanol (1.5 or 3.0 g/kg) in the hypothalamus and amygdala. We found that acute ethanol administration dose-dependently increased c-fos activity in the the Paraventricular nucleus of the hypothalamus (PVN). Interestingly, binge-ethanol exposure during adolescence significantly reduced basal c-fos activity during adulthood in the Central nucleus of the amygdala (CeA) and the Arcuate nucleus of hypothalamus (Arc). We conclude that binge-like ethanol administration during adolescence causes long-term disturbances in basal neural activity in brain areas critically involved with ethanol consumption.
El consumo en atracón durante la adolescencia está asociado con neurotoxicidad y con el riesgo de desarrollar un trastorno en el uso de alcohol. Diversos estudios muestran que la administración aguda y crónica de alcohol en ratas adultas altera la expresión de c-fos, un marcador indirecto de actividad celular, en diferentes áreas cerebrales. Nosotros evaluamos si el patrón de consumo de alcohol en atracón durante la adolescencia tiene un impacto en la actividad basal de c-fos en esas regiones activadas por el alcohol. Utilizamos ratas Sprague-Dawley en su día post-natal 25 (PND25) tratadas con suero salino (grupo SP) o con etanol tipo atracón (grupo BEP) durante dos días consecutivos, en intervalos de 48 h, durante 14 días (PND25- PND38). En la edad adulta (PND63) y después de 25 días sin etanol, evaluamos la inmunorreactividad para c-fos en respuesta a una administración aguda de suero salino o etanol (1,5 ó 3,0 g/kg) en diferentes regiones cerebrales. La administración de alcohol incrementó de manera dosis-dependiente la actividad de c-fos en el núcleo paraventricular del hipotálamo. Además la exposición a etanol tipo atracón durante la adolescencia disminuyó la actividad basal de c-fos en la adultez en el núcleo central de la amígdala y en el núcleo arqueado del hipotálamo. Concluimos que el consumo de alcohol en atracón durante la adolescencia causa problemas a largo plazo en la actividad basal de regiones cerebrales implicadas en el consumo de alcohol.