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Effects of chemical sympathectomy in neonatal and adult mice on C-1300 neuroblastoma tumor growth and catecholamine content.

The in situ C-1300 murine neuroblastoma (MNB) tumor model was used to investigate the influence of 6-hydroxydopamine (6HD)-induced sympathectomy on tumor growth and catecholamine concentration. One week (adult) and 3 weeks (neonatal) after sympathectomy, mice were implanted with 10(6) disaggregated MNB cells. The time interval between implantation of MNB cells and detection of palpable tumor (tumor onset time), transverse tumor diameter, tumor weight, tumor weight to body weight ratio, and tumor catecholamine concentration were determined. Sympathectomy following 6HD administration was confirmed by analysis of catecholamine concentrations in the heart and spleen by high-pressure liquid chromatography. Treatment of adult animals with 6HD reduced the mean heart and spleen norepinephrine (NE) concentrations to less than 20% of controls (vehicle treated). Neonatal sympathectomy decreased the average heart and spleen NE concentrations to less than 10% of comparable control mice. Whole brain NE and dopamine concentrations were not altered by treatment with 6HD in either age group. Tumor onset time following implantation of MNB cells was significantly increased in animals sympathectomized as either neonates or as adults. In contrast, MNB tumor growth rate following tumor onset was significantly inhibited in animals sympathectomized as neonates but not as adults. The catecholamine concentrations of tumors removed from control and sympathectomized mice 8 days after tumor onset were determined. Tumor NE and dopamine concentrations were increased 9.09 +/- 2.8- (SE) and 7.03 +/- 1.8-fold, respectively, in mice sympathectomized as neonates. There were no significant differences in the NE and dopamine concentrations of tumors obtained from sympathectomized and control adult mice. Pretreatment with desmethylimipramine prior to 6HD administration prevented destruction of sympathetic neurons, inhibition of tumor growth rate, and the increase in tumor catecholamine concentration observed in neonatally sympathectomized mice. These data suggest that the influence of chemical sympathectomy on MNB tumor growth and biochemical differentiation, as defined by catecholamine content, are age dependent.