Modification of nocturnal spontaneous and adrenergic-induced feeding in the rat following either A5 or A7 lesions

The ingestive profiles of intact, A5 and A7 damaged animals were examined during the 2-hr nocturnal period following onset of the dark cycle. A5, A7 and intact rats consumed comparable amounts of food following initial access to food nocturnally. Sebsequent feeding declined in A5 animals below control values and failed to return to baseline at the end of the nocturnal period examined. A7 damaged rats appeared more resistant to the appetite suppressing effects of initial meal taking and consumed more food than control animals. Only A5 damaged rats were noted to be hyperdipsic during the immediate 10 postoperative days. Intracranial injection of 1-norepinephrine bitartrate (10 ug/ul) into the paraventricular nucleus (PVN) of the hypothalmus produced a reliable facilitation of feeding in A5, A7 and intact rats during the first hour of the dark cycle. A5 rats exhibited the largest increase in feeding elicited by NE administration into the PVN. This feeding response was observed in rats with A5 lesions regardless of whether testing was carried out during the initial hours of the dark cycle or during a predetermined "satiation" test. A5 lesions also effected a marked hyperglycemia while A7 lesions were ineffective in this respect. Taken together these data suggest the A5 and A7 cell groupings regulate spontaneous feeding within a rostrally coursing feeding circuitry and appear to interact with the PVN in the elicitation of noradrenergic feeding.