Feeding elicited by cholinergic and adrenergic hypothalamic stimulation of anorectic tumor-bearing rats.

Injection of norepinephrine into the hypothalamus of methylcholanthrene sarcoma-bearing rats elicited a normal feeding response both prior to and following the development of anorexia. Feeding elicited by cholinergic stimulation of the hypothalamus of tumor-bearing rats with carbachol was normal prior to the onset of anorexia, but decreased in magnitude as the anorexia became more severe. These data indicate that noradrenergic feeding mechanisms in the hypothalamus of tumor-bearing rats are functioning normally during anorexia. However, cholinergic feeding mechanisms in the hypothalamus of tumor-bearing rats appear to be depressed to the same degree as ad lib intake, possibly through adaptation or depletion of endorphin systems that mediate stress-induced feeding.