Effect of immobilization on in vitro thyrotropin-releasing hormone release from brain septum in wild-type and corticotropin-releasing hormone knock-out mice

There is considerable evidence linking alcohol consumption, sedation, and thyrotropin-releasing hormone (TRH) in the brain septum. We have shown that ethanol in clinically relevant concentrations can in vitro induce TRH release from the septum by a mechanism involving neuronal swelling. Corticotropin-releasing hormone-deficient (CRH-KO) mice serve as an interesting model to help us understand the role of CRH in the regulation of different neuroendocrine systems. The aim of this study was to compare TRH release activity in the brain septum at basal and stress conditions in CRH-KO mice and their wild-type (WT) littermates. Experimental mice were decapitated immediately or 3 h after single (2 h) or repeated (seven times for 2 h daily) immobilization stress. The brain septum was immediately cut out and incubated to measure basal-, ethanol-, and hyposmosis-stimulated TRH release in vitro. Ethanol in isosmotic medium or hyposmotic medium stimulated TRH release from mice septal explants from WT and CRH-KO mice. The response was disturbed immediately after immobilization and recovered 3 h later. Our results show that immobilization stress transiently affects the TRH system in brain septum. Inborn absence of CRH does not affect septal TRH and its response to ethanol before and 3 h after immobilization.