AV3V NEURONS THAT SEND AXONS TO HYPOTHALAMIC NUCLEI RESPOND TO THE SYSTEMIC INJECTION OF IL-1-BETA

The single neuron activity in the anteroventral region of the third ve ntricle (AV3V) was extracellularly recorded in urethan and alpha-chlor alose anesthetized rats. Electrical stimulation of the medial preoptic area (mPOA) and the paraventricular nucleus (PVN) revealed a reciproc al neural connection between the AV3V and these hypothalamic nuclei wi th an ipsilateral preponderance. All the AV3V neurons, which were anti dromically activated by the stimulation of the mPOA or the PVN, altere d their activity after the systemic injection of interleukin (IL)-1 be ta. On the other hand, only about 60% of the AV3V neurons that showed orthodromic responses were affected by IL-1 beta. In seven of nine AV3 V neurons that were electrophysiologically identified to send their ax ons to the mPOA or the PVN, the recombinant human IL-1 beta-induced ex citation and inhibition were attenuated by a local application of sodi um salicylate through multibarreled micropipettes. These results sugge st that the AV3V neurons alter their activity in response to the blood -borne IL-1 beta, at least in part, through a local synthesis of prost anoids and then send the information to the mPOA and PVN.