mRNA expression of corticotropin-releasing factor and urocortin 1 after restraint and foot shock together with alprazolam administration

Corticotropin-releasing factor (CRF) is expressed in the paraventricular nucleus of the hypothalamus (PVN), and act centrally to provoke stress-like autonomic and behavioral responses. Urocortins 1–3 are additional ligands to the CRF receptors 1 and 2. Ucn 1 neurons are primarily concentrated in the Edinger–Westphal (EW) nucleus and also have been associated with stress responses. It is also known that UCN 1 respond in different ways depending on the stressor presented. Benzodiazepines can act via the CRF peptidergic system and chronic administration of alprazolam does not interfere with CRF mRNA expression in the PVN, but significantly increase Ucn 1 mRNA expression in the EW. The aim of our study was to investigate the relationship between different stressor stimuli, foot shock (FS) and restraint (R), and the mRNA expression of CRF and Ucn 1 in the PVN and EW using alprazolam (A). We employed fos activation and in situ hybridization. Restraint group presented increased fos-ir and CRF mRNA expression in the PVN compared to FS group. The stress responses of R group were prevented by A. In the EW, fos-ir was higher in the FS group than in the R group, whereas Ucn 1 mRNA expression was higher in the R group than in the FS group. Alprazolam significantly increased fos-ir and Ucn 1 mRNA expression in both groups. Our results show that PVN and EW respond in different ways to the same stressors. Furthermore, EW of stressed animals replies in a complementary way comparing to PVN with the use of Alprazolam.

Research highlights▶ fos-ir was increased in the PVN after restraint comparing to foot shock but significantly lower in the restraint plus alprazolam and foot shock plus alprazolam. ▶ CRF mRNA expression in the PVN was significantly higher in the restraint than in the foot shock, but was even lower in the restraint plus alprazolam and foot shock plus alprazolam. However, only the difference between restraint plus alprazolam and restraint-only groups was significant. ▶ fos-ir in the EW was significantly increased in the restraint and foot shock groups than in the control, but higher in the foot shock than in the restraint group. ▶ Ucn 1 mRNA expression was higher in the restraint than in the foot shock group. ▶ Alprazolam administration significantly increased fos-ir and upregulated Ucn 1 mRNA expression in the EW within the restraint and foot shock groups.