Long-Term Pilocarpine Pre-Treatment: Weight and Survival in Irradiated Rats

Objectives: To assess changes in body weight and survival rate among irradiated rats treated with pilocarpine (Pi), and to compare them to irradiated rats without Pi treatment and to control. Material and methods: One hundred and seven Wistar rats were divided into 5 groups: A4 – 4 weeks Pi prior to irradiations; A3 – 3 weeks Pi prior to irradiations; A0 - Pi at start of irradiations; X – irradiations only; Control - no Pi, no irradiations. Pi (5mg/kg/day) was dissolved and administered in drinking water. Rats were exposed to a total irradiation of 42 Gy equally divided into 6 weekly doses. Rats were sacrificed at 1, 2, 4 and 8 weeks post-irradiation. Statistical analysis of the differences in mean body weights was performed by one-way ANOVA and survival analysis by Kaplan-Meier. Results: Starting from irradiations and thereafter, the mean body weight in the Control was significantly higher than in all other groups (p<0.05). Prior to and during irradiations the mean body weight of X group was not significantly different from Pi-treated groups (A4, A3, A0) (p>0.05) however, post-irradiation it was significantly lower (p<0.001). Throughout the study, the survival rate in the Control was significantly higher than that in A0, A3 and X groups (p<0.018, p<0.024 and p<0.001, respectively) but not from A4 (p>0.05). Prior to and during irradiations no statistical differences in the survival rate were found among all irradiated groups (p>0.05). Post-irradiation, survival rate in X group was significantly lower than in A4, A3 and Control groups (p<0.004, p<0.018 and p<0.001, respectively). No statistical differences were found between the Control and all Pi-treated groups (p>0.05). Conclusions: Post-irradiation decrease in body weight was observed in all irradiated groups irrespective of Pi administration. However, long-term Pi pre-treatment significantly improved survival rate of irradiated rats, suggesting a critical systemic irradiation-protective effect of Pi.