The effects of hibernation on the myenteric plexus of the golden hamster small and large intestine

We have examined the effects of hibernation on the neurochemical compositio n of myenteric neurones in the small and large intestine of the golden hams ter using immunohistochemical and histochemical techniques. Hibernation was induced in golden hamsters by altering the photoperiod and external ambien t temperature. Age-matched hamsters kept at room temperature and those kept at 5 degrees C but which failed to hibernate were used as controls. Cell c ounts were carried out to examine possible changes in the numbers of cell b odies immunoreactive to all of the markers examined. The results demonstrat ed a significant increase during hibernation in the number of neurones immu noreactive to vasoactive intestinal polypeptide, substance P and calcitonin gene-related peptide; cell bodies positive for tyrosine hydroxylase, which were largely absent in the control animals, were prominent in the hibernat ing animals. There was a significant decrease in the number of neurones imm unoreactive to 5-hydroxytryptamine, and no significant changes in the numbe rs of neurones immunoreactive to protein gene-product and nitric oxide synt hase. It is suggested that selective upregulation and downregulation of mye nteric neurones containing certain neurotransmitters may occur as a protect ive mechanism during hibernation to maintain the integrity of the muscular and mucosal layers of the intestine in the absence of luminal contents.