DISTRIBUTION AND CELLULAR-LOCALIZATION OF VASOPRESSIN MESSENGER-RNA IN THE OVINE BRAIN, PITUITARY AND PINEAL GLANDS

In this study, in situ hybridization histochemistry was used to determ ine the regional and cellular localization of vasopressin-neurophysin II (AVP) mRNA in the sheep brain and pituitary with an S-35-labelled s ynthetic 45-mer oligonucleotide probe complementary to the bovine AVP gene. The highest densities of labelled cell bodies were found in the paraventricular nucleus (PVN), supraoptic nucleus (SON) and suprachias matic nucleus (SCN) of the hypothalamus, though such cells were also f ound in other regions of the diencephalon, including the accessory mag nocellular nuclei. Labelled cells were also observed sparsely distribu ted in every major cortical field as well as in choroid plexus and the pineal gland. No AVP mRNA-expressing cells were found in the bed nucl eus of the stria terminalis, the amygdala, or in the medulla and brain stem. In the pituitary, a dense AVP mRNA signal was observed in the in termediate lobe whereas, cells in the anterior or neural lobe did not express AVP mRNA. The dense population of AVP-expressing neurons in bo th magnocellular and parvocellular fields of the hypothalamus support major roles of AVP in both posterior and anterior pituitary function. Finally, the extrahypothalamic distribution of AVP mRNA transcripts su ggest that vasopressinergic neurons may be involved in diverse physiol ogical functions, including the regulation of pineal function and cogn ition.