Lateral hypothalamus involvement in control of stress response by bed nucleus of the stria terminalis endocannabinoid neurotransmission in male rats

Abstract

The endocannabinoid neurotransmission acting via local CB1 receptor in the bed nucleus of the stria terminalis (BNST) has been implicated in behavioral and physiological responses to emotional stress. However, the neural network related to this control is poorly understood. In this sense, the lateral hypothalamus (LH) is involved in stress responses, and BNST GABAergic neurons densely innervate this hypothalamic nucleus. However, a role of BNST projections to the LH in physiological responses to stress is unknown. Therefore, using male rats, we investigated the role of LH GABAergic neurotransmission in the regulation of cardiovascular responses to stress by CB1 receptors within the BNST. We observed that microinjection of the selective CB1 receptor antagonist AM251 into the BNST decreased the number of Fos-immunoreactive cells within the LH of rats submitted to acute restraint stress. Treatment of the BNST with AM251 also enhanced restraint-evoked tachycardia. Nevertheless, arterial pressure increase and sympathetically-mediated cutaneous vasoconstriction to restraint was not affected by CB1 receptor antagonism within the BNST. The effect of AM251 in the BNST on restraint-evoked tachycardia was abolished in animals pretreated with the selective GABAA receptor antagonist SR95531 in the LH. These results indicate that regulation of cardiovascular responses to stress by CB1 receptors in the BNST is mediated by GABAergic neurotransmission in the LH. Present data also provide evidence of the BNST endocannabinoid neurotransmission as a mechanism involved in LH neuronal activation during stressful events.

Site-Specific Regulation of Stress Responses Along the Rostrocaudal Axis of the Insular Cortex in Rats

“…Sympathetically mediated vasoconstriction of cutaneous beds during aversive threats reduces skin temperature ( Blessing, 2003 ; Vianna and Carrive, 2005 ). Therefore, the drop in tail skin temperature during restraint was measured as an indirect measure of the sympathetic response to cutaneous beds ( Oliveira et al, 2015 ; Gomes-de-Souza et al, 2021 ). Measurements of tail skin temperature were performed at 5 and 0 min before restraint for basal values; 5, 10, 20, 40, and 60 min during restraint, as well as 10, 20, 30, 40, 50, and 60 min during the recovery phase ( Benini et al, 2019 ; Barretto-de-souza et al, 2021 ).…”

“…The procedures for the assessment of Fos-positive cells were as previously described ( Gomes-de-Souza et al, 2021 ). Briefly, 90 min after the onset of the restraint stress (i.e., 30 min following the termination of the restraint stress session), the rats were anesthetized (urethane, 1.2 g/kg, i.p.)…”

“…Tail skin temperature recording was performed as previously described ( Oliveira et al, 2015 ; Gomes-de-Souza et al, 2021 ). Briefly, the recordings were performed using a thermal camera (IRI4010, InfraRed Integrated Systems Ltd., Northampton, United Kingdom) and the temperature was obtained at five sites along the tail, and then the mean was obtained for each record ( Oliveira et al, 2015 ; Gomes-de-Souza et al, 2021 ).…”

Why Do Marijuana and Synthetic Cannabimimetics Induce Acute Myocardial Infarction in Healthy Young People?

“…In one study, injection of a GPR18 agonist into the RVLM increased HR [ 215 ]. HR was increased following microinjection of AEA into the dorsal periaqueductal grey (dPAG; [ 217 , 218 , 219 ]) but decreased upon microinjection of an inhibitor of AEA degradation into the bed nucleus of the stria terminalis (BNST; [ 222 , 223 , 224 ]); both effects were mediated via CB 1 -Rs.…”

Cerebellar Prediction and Feeding Behaviour

“…As well as affecting appetite in healthy weight individuals, anxiety is also strongly related to eating disorders including anorexia nervosa. Imaging studies have shown an altered cerebellar network connectivity in anorexia nervosa patients compared to healthy controls, in particular increased activity within the vermis [178,179,180]. The disorder is associated with altered food-cue processing and decreased appetite upon presentation of food cues [172,181,182].…”