The effect of naloxone on tumor growth and survival time was studied in mice with neuroblastoma tumors. Daily s.c. injections of either 5, 10, 15, or 20 mg/kg naloxone were initiated either 2 weeks prior to tumor cell inoculations (pre-treated groups) or one week after tumor transplantation (post-treated groups). The S20Y cell line, cloned from A/Jax murine C1300 neuroblastoma, was utilized and each animal was inoculated with 106 cells. All mice in the saline- tumor and naloxone post-treated groups, developed tumors within 3 weeks after tumor cell inoculation. In the naloxone pre-treated groups, 4 of 12 mice exposed to 20 mg/kg, 2 of 12 mice exposed to 15 mg/kg, and 1 of 12 mice exposed to 10 mg/kg, did not develop tumors within the 91-day post-inoculation period. Three animals in the 20 mg/kg naloxone pre-treated group developed tumors between 43 and 63 days after tumor cell inoculation. Tumor dimensions were often reduced in naloxone-treated animals but a dose-response relationship was not found in regard to the magnitude of alterations in tumor size. At the time of death, tumor sizes of control and naloxone-exposed mice were similar. In general, tumor-bearing mice receiving naloxone lived longer than saline-tumor controls, with animals receiving higher drug dosages surviving for the longest time. In contrast to a mean survival time of 27 days for controls, naloxone pre-treated groups had increases in survival times of 25-61%, whereas naloxone post- treated groups exhibited increases of 20-40%. The median day of death for all mice exposed to naloxone was prolonged by 21-75%, occuring 6-21 days after the 28-day median for saline-tumor controls. These results suggest that naloxone, a non-addictive compound, is an effective agent in modulating neoplasia.
All Science Journal Classification (ASJC) codes
- Biochemistry, Genetics and Molecular Biology(all)
- Pharmacology, Toxicology and Pharmaceutics(all)