Análise da participação do sistema endocanabinóide da amídala na interação entre a exposição de estresse e o consumo de etanol em camundongos

Abstract

Excessive alcohol consumption represents a serious public health issue with deleterious consequences for individual and social well-being. The search for relief in stressful situations is often associated with increased alcohol consumption, establishing a vicious cycle that can lead to dependence. In this context, the endocannabinoid system (ECS), an endogenous signaling system, emerges as an important modulator of reward behavior, acting as a homeostatic system and regulating various physiological functions, including mood, appetite, sleep, and memory. The interaction of the ECS with the dopaminergic system is fundamental for reward processing, as it modulates behavior related to the pursuit of euphoric effects. The amygdala and the bed nucleus of the stria terminalis (BNST) form a crucial neural circuit for emotional and motivational regulation. While the amygdala assigns emotional value to stimuli, the BNST integrates information with the immune system, influencing motivation and the pursuit of reinforcement. Stressful factors culminate in the activation of the hypothalamic-pituitary-adrenal (HPA) axis, and its dysregulation contributes to the exacerbation of emotions, intensifying the search for relief through alcohol consumption. Furthermore, the activation of CB1 receptors, mainly located in the brain and central nervous system, attenuates the stress response in the amygdala and modulates neuronal activity related to reward in the BNST, while CB2 receptors may modulate the inflammatory response and neurotoxicity induced by stress and alcohol consumption. Studies show that the ECS plays a fundamental role in regulating processes related to stress and substance use, including ethanol, and enzymes such as FAAH (fatty acid amide hydrolase) and MAGL (monoacylglycerol lipase) are involved in the metabolism of endocannabinoids, modulating the levels of anandamide and 2-AG, respectively. These molecules are associated with regulating the stress response and drug-seeking behavior. In this study, C57BL/6J mice were used. After the experimental protocol, the brains were collected for molecular analysis. Amygdala samples were dissected and sectioned using a cryostat for subsequent RNA extraction, followed by cDNA synthesis and pre-amplification with specific primers. The relative expression of the CB1, CB2, FAAH, and MAGL genes was evaluated using duplex RTPCR, normalized with the reference gene Pde10a. In this context, it was observed that the group of animals subjected to the unpredictable intermittent stress protocol consumed more ethanol compared to the control group. Moreover, the molecular analysis in our animals revealed significant alterations in gene expression levels in the amygdala and BNST, suggesting that stress not only influences consumption behavior but also promotes molecular changes in these nuclei. Thus, it is evident that the interplay between stress, the endocannabinoid system, and alcohol consumption presents a complex scenario that warrants attention.