Afferent renal inputs to paraventricular nucleus vasopressin and oxytocin neurosecretory neurons

Extracellular single-unit recording experiments were done in pentobarbital sodium-anesthetized rats to investigate the effects of electrical stimulati on of afferent renal nerves (ARN) and renal vein (RVO) or artery (RAO) occl usion on the discharge rate of putative arginine vasopressin (AVP) and oxyt ocin (Oxy) neurons in the paraventricular nucleus of the hypothalamus (PVH) . PVH neurons antidromically activated by electrical stimulation of the neu rohypophysis were classified as either AVP or Oxy secreting on the basis of their spontaneous discharge patterns and response to activation of arteria l baroreceptors. Ninety-eight putative neurosecretory neurons in the PVH we re tested for their response to electrical stimulation of ARN: 44 were clas sified as putative AVP and 54 as putative Oxy neurons. Of the 44 AVP neuron s, 52% were excited, 7% were inhibited, and 41% were nonresponsive to ARN s timulation. Of the 54 Oxy neurons, 43% were excited, 6% inhibited, and 51% were not affected by ARN. An additional 45 neurosecretory neurons (29 AVP a nd 16 Oxy neurons) were tested for their responses to RVO and/or RAG. RVO i nhibited 42% of the putative AVP neurons and 13% of the putative Oxy neuron s. On the other hand, RAO excited 33% of the AVP and 9% of the Oxy neurons. No AVP or Oxy neurons were found to be excited by RVO or inhibited by RAG. These data indicate that sensory information originating in renal receptor s alters the activity of AVP and Oxy neurons in the PVH and suggest that th ese renal receptors contribute to the hypothalamic control of AVP and Oxy r elease into the circulation.