VASOPRESSIN-SECRETING NEURONS OF THE PARAVENTRICULAR NUCLEUS RESPOND TO OROPHARYNGEAL APPLICATION OF HYPERTONIC SALINE

Responses of electrophysiologically identified vasopressin (VP)-secreting neurones of the hypothalamic paraventricular nucleus in the rat were recorded following the application of hypertonic saline (2-4 M) to the tongue and oropharynx. Fourteen of the 15 VP-secreting neurones were excited by the stimulus, response onset occurring within a few seconds. Of the 5 neighbouring unidentified neurones, or those identified as projecting to the median eminence, 3 were also found to respond to the stimulus. All of the responses were sustained during the period of application and were reversed following wash-off with distilled water, when neurones were found to be substantially inhibited. The results of this study indicate a role of ascending gustatory sensory afferent innervation as a predictive indicator of changing plasma osmotic pressure. © 1990.