Antagonism of brain opioid peptide action reduces hibernation bout duration

The effect of continuous intracerebroventricular (i.c.v.) administration of naloxone on the duration of individual bouts of hibernation was investigated in the golden-mantled ground squirrel ( Citellus lateralis). Following entrance into hibernation, naloxone was continuously administered by an osmotic minipump at a rate of 1 μl/h through a chronically implanted unilateral i.c.v. cannula guide. Naloxone (1, 5 and 7.5 μg/μl) produced a dose-dependent reduction in hibernation bout duration ranging from 1 to 4 days (13.9–62.3% of expected bout duration). These data suggest that selected endogenous opioid system neurons may contribute to the CNS maintenance of the hibernating state and, consequently, to the overall conservation of energy in this species.