Effects of chronic atropine administration on regional vasoactive intestinal polypeptide concentrations in rat brain

J M Petit1, L Denoroy, M Jouvet

  • 1Laboratoire de Médecine Expérimentale, INSERM U52-CNRS URA 1195, Université Claude Bernard, Lyon, France.

We studied the effects of 14 days' treatment with atropine sulfate (10 or 20 mg/kg per day) or atropine methyl bromide (20 mg/kg per day) on the concentration of vasoactive intestinal polypeptide like-immunoreactivity (VIP-LI) in the rat brain. VIP-LI in the anterior pituitary as well as brain areas dissected from treated and control rats was measured by radioimmunoassay. VIP-LI in the hypothalamus, and especially in the suprachiasmatic nucleus, was not affected by chronic atropine sulfate administration. Conversely, the same treatment induced a decrease in VIP-LI in the cerebral cortex, dorsal raphe, locus coeruleus, ventrolateral and dorsolateral medulla. In these structures, the decrease in VIP-LI was probably due to muscarinic receptor blockade in the central nervous system rather than in the peripheral nervous system since variations in VIP-LI were not observed after atropine methyl bromide treatment. These findings suggest the existence of a muscarinic control of VIP-LI in discrete brain areas of the rat and particularly in caudal brainstem structures.

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