Catecholamine, indoleamine and corticosteroid responses in mice bearing tumors

The neurochemical and endocrine responses to inoculation of mice with the m urine lymphoma cell line AW5E was studied. This cell line was chosen becaus e it is NK cell lysis resistant and thus does not induce a normal immune re sponse. Immune activation has long been known to be a potent stimulator of the hypothalamo-pituitary-adrenocortical (HPA) axis as well as brain catech olamine and indoleamine metabolism, involving increases in the brain concen trations of catabolites of norepinephrine (NE) and serotonin (5-HT), as wel l as free tryptophan. Mice injected intravenously with AW5E tumor cells exh ibited small increases in plasma corticosterone and hypothalamic NE and 5-H T catabolites one day after injection. There were no significant changes af ter 6 or 8 days, but a sustained increase in hypothalamic NE and 5-HT metab olism appeared 10 days after injection. There were similar, but more limite d changes in the brain stem and prefrontal cortex. On the last day tested ( day '14), plasma corticosterone was slightly elevated, as were hypothalamic dopamine, NE and 5-HT catabolites and tryptophan, These results indicate t hat inoculation with AW5E tumor cells increases brain catecholamine and ser otonin metabolism, the hypothalamus being the most sensitive region. The mo st marked increases occurred in the few days preceding death, and thus may be associated with the pathology of the tumor growth. Copyright (C) 2000 S. Karger AG, Basel.