Distribution and cellular localization of vasopressin mRNA in the ovine brain, pituitary and pineal glands.

In this study, in situ hybridization histochemistry was used to determine the regional and cellular localization of vasopressin-neurophysin II (AVP) mRNA in the sheep brain and pituitary with an 35S-labelled synthetic 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 suprachiasmatic nucleus (SCN) of the hypothalamus, though such cells were also found in other regions of the diencephalon, including the accessory magnocellular nuclei. Labelled cells were also observed sparsely distributed 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 nucleus of the stria terminalis, the amygdala, or in the medulla and brainstem. In the pituitary, a dense AVP mRNA signal was observed in the intermediate lobe whereas, cells in the anterior or neural lobe did not express AVP mRNA. The dense population of AVP-expressing neurons in both 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 suggest that vasopressinergic neurons may be involved in diverse physiological functions, including the regulation of pineal function and cognition.