Increase in brain serotonin level and concomitant reduction in food intakeand body weight of mice bearing chemically - Induced fibrosarcoma

The investigation was carried out to elucidate whether growth of malignant tumor is associated with alterations in central neurotransmitter level of t he host. The concentrations of serotonin (5-HT) and its metabolite 5-hydrox yindoleacetic acid (5-HIAA) were measured by HPLC with electrochemical dete ction in discrete areas of the brain of Swiss mice bearing benzo(a) pyrene - induced primary fibrosarcoma. The level of 5-HT was markedly elevated in raphe nucleus of the brain from 0.86+/-0.15 mug/g tissue in controls to 2.2 +/-0.65 mug/g and 3.7+/-0.86 mug/g tissue in early (tumor volume < 1.5 cm(3 )) and advanced stage of the disease (tumor volume > 3 cm(3)) respectively. 5-HT values also increased appreciably in midbrain and hypothalamus. Tn co ntrast, platelet 5-HT level declined significantly (p < 0.05) in tumor bear ing animals. Like 5-HT, 5-HIAA level also elevated in discrete areas of the brain. The rise in 5-HT concentration in brain was paralleled by progressi ve decline in food intake and body weight. In summary, the results demonstr ate marked rise in brain 5-HT level in mice bearing chemically-induced fibr osarcoma and this may account for tumor-associated anorexia and cachexia.