THE DISTRIBUTION OF VASOACTIVE INTESTINAL PEPTIDE(2) RECEPTOR MESSENGER-RNA IN THE RAT-BRAIN AND PITUITARY-GLAND AS ASSESSED BY IN-SITU HYBRIDIZATION

The distribution of rat vasoactive intestinal peptide(2) (VIP2) recept or messenger RNA in the brain and the pituitary gland was examined by in situ hybridization and by ribonuclease protection assay. Labelled c ells were found chiefly in the suprachiasmatic nucleus, the central nu cleus of the amygdala and the thalamus (the lateral geniculate nucleus , and the paraventricular, mediodorsal and ventral nuclei of the thala mus). The distribution of the VIP2 receptor overlaps only in part with that of the VIP1 receptor, for example in the hippocampus, where VIP2 receptor messenger RNA was found in the pyramidal cells of the CA1-CA 3 subfields and in the granule cells of the dentate gyrus. Small numbe rs of neurons containing high concentrations of VIP2 receptor messenge r RNA were present in the brainstem in the principal sensory trigemina l nucleus and in the substantia gelatinosa of the spinal cord, suggest ing a role for the VIP2 receptor in the processing of sensory informat ion. The presence of the VIP2 receptor in the suprachiasmatic nucleus suggests that it is this receptor subtype which is involved in the con trol of circadian rhythms.