Endocrine Abstracts

Acute stressors can active the reproductive function depending on estrogen priming. Corticotropin-releasing hormone (CRH) has been implicated as mediator of stress-induced effects on hypothalamus–pituitary–gonadal axis (HPG), acting in the limbic system, paraventricular nucleus and noradrenergic (NA) neurons. Antalarmin and astressin2-B are selective CRH-R1 and CRH-R2 antagonists, respectively. We investigated the mediation of CRH-R1 and/or CRH-R2 receptors and of locus coeruleus (LC), A1 and A2 neuron groups in the effects of acute stress on LH and FSH secretion at proestrus morning. Wistar rats showing regular estrous cycles received a catheter in the jugular vein one day before acute stress. At proestrus morning, it was injected antalarmin (1 mg/kg i.v.), asstressin2-B (4.2 nmol i.c.v.) or vehicle and 30 min later was performed the restraint stress for 30 min. Blood samples were collected before, during and after restraint stress to measure FSH and LH by RIA. At the end of the experiment, the rats were perfused and brain were removed to carry out immunofluorescence for tiroxine hydroxylase (TH) and /FOS in LC, A1 and A2 cell groups. Restraint stress increased FSH and LH levels for 30 min. Antalarmin blocked stress-induced increase of FSH and LH whereas astressin2-B only blocked the increase of FSH secretion. The TH activity increased in the LC and A2 groups and a minor magnitude in A1 group. Only the antalarmin injection reduced this effect principally in the LC. These data indicate different roles of CRH receptors in the stress restraint-effects on gonadotropins secretion at proestrus. The CRH-R1 more than CRH-R2 receptor would be essential to the HPG axis stimulation by acute stress and this response would be mediated at least in part by NA neurons, principally in the LC.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This work was supported, however funding details unavailable.