Lesions in lateral parabrachial nucleus enhance drinking to angiotensin II and isoproterenol.

The lateral parabrachial nucleus (LPBN) has been shown to be anatomically linked to a number of forebrain nuclei and medullary structures implicated in the control of body fluid balance and cardiovascular regulation. Although these connections suggest a role for the LPBN in body fluid homeostasis, there is currently little or no physiological or behavioral data to support this notion. The purpose of the present series of experiments was to determine the importance of the ventrolateral region of the LPBN (VLLPBN) in the behavioral response to various thirst challenges. Rats with electrolytic lesions of the VLLPBN and control rats were studied after administration of angiotensin II (ANG II) (1.5 and 3.0 mg/kg), isoproterenol (30 and 100 micrograms/kg), polyethylene glycol (20%) and hypertonic saline (4 and 12%). It was found that rats with lesions drank more in response to ANG II and isoproterenol administration than did control animals.