Salt-loading increases vasopressin and vasopressin 1b receptor mRNA in the hypothalamus and choroid plexus

The choroid plexus plays a pivotal role in the production of cerebrospinal fluid (CSF). Messenger RNA (mRNA) transcripts encoding arginine vasopressin (AVP) and the vasopressin 1b receptor (V_1bR) are found in various structures of the central nervous system, including the choroid plexus. The present study measured AVP and V_1bR mRNA production in response to plasma hyperosmolality. Compared to rats maintained on water, 2% salt-drinking rats had increased levels of AVP and V_1bR mRNAs in the supraoptic (SON) and paraventricular (PVN) nuclei of the hypothalamus and in the choroid plexus. The increase in V_1bR mRNA in the SON and PVN as a result of plasma hyperosmolality may reflect changes in receptor production that, in turn, have a role in AVP autoregulation of hypothalamic magnocellular neurons. The increase of AVP and V_1bR mRNAs in the choroid plexus further shows the involvement of AVP in the regulation of brain water content and cerebral edema.