Brainstem neuronal and behavioral activation by corticotropin-releasing hormone depend on the behavioral state of the animal

Abstract

Central administration of corticotropin-releasing hormone (CRH) is known to enhance locomotion across a wide range of vertebrates, including the roughskin newt, Taricha granulosa. The present study aimed to identify the CRH effects on locomotor-controlling medullary neurons that underlie the peptide’s behavioral stimulating actions. Single neurons were recorded from the rostral medullary reticular formation before and after intraventricular infusion of CRH in freely behaving newts and newts paralyzed with a myoneural blocking agent. In behaving newts, most medullary neurons showed increased firing 3-23 min after CRH infusion. Decreases in firing were less common. Of particular importance was the finding that in behaving newts, medullary neurons showed a cyclic firing pattern that was strongly associated with an increase in the incidence of walking bouts, an effect blocked by pretreatment with the CRH antagonist, alpha-helical CRH and not seen following vehicle administration. In contrast, the majority of medullary neurons sampled in immobilized newts lacked temporal cyclicity in their firing patterns following intraventricular infusion of CRH. That is, there was no evidence for a fictive locomotor activity pattern. Our results indicate that the actual expression of locomotion is a critical factor in regulating the behavior-activating effects of CRH and underscore the importance of using an awake, unrestrained animal for analysis of a hormone’s neurobehavioral actions.

Visual preconditioning reduces emergence delirium in children undergoing ophthalmic surgery: a randomised controlled trial

“…34,35 The decreased levels of CRF in the visual preconditioning group may contribute to the prolonged emergence time and reduction in heart rates after anaesthesia as CRF plays an important role in regulating behavioural state and heart rate changes. 36,37 A study with a larger sample size will be conducted in the future to explore the underlying biological mechanism. Although benefits of the prophylactic treatment with eyepatch by covering the eye to be operated were achieved by this prospective, randomised study, several limitations should be noted.…”