Chronic hypoxia affects peripheral and central vasoactive intestinal peptide-like immunoreactivity in the rat.

The influence of long-term hypoxia on vasoactive intestinal peptide-like immunoreactivity (VIP-LI) in discrete brain areas and peripheral structures was assessed by RIA. Rats were exposed to normobaric hypoxia (10% O2-90% N2) for 14 days. VIP-LI was significantly increased in carotid bodies of hypoxic animals (204% vs. normoxic animals). On the other hand, VIP-LI was decreased in the anterior pituitary (-68%), suprachiasmatic nuclei (-29%) and periventricular nuclei (-26%). No significant variation in VIP-LI was observed in other peripheral structures and discrete brain area studied. These results suggest that long-term hypoxia induces alterations in VIP systems implicated in chemoreception, biological rhythms and neuroendocrine functions.