Effects of ionizing radiation on schedule-induced polydipsia

The aim of the present work was to explore and evaluate the effects of ionizing radiation on schedule-induced polydipsia. Five food deprived rats were used as subjects and submitted to baseline procedure, after that they were divided in two experimental groups: two subjects were exposed to a fixed-time 60 seconds of food schedule (FT 60 s) and three were exposed to a fixed-interval 60 seconds of food schedule (FI 60 s). Once schedule-induced polydipsia was developed, four subjects were exposed to ionizing radiation of 4,5 Gy. A second exposure to ionizing radiation of 6,0 Gy was done with three subjects thirty-six days after the first exposure. For the 4,5 Gy the results showed that even the lever press response or the polidipsia decreased at the session occurred two hours after exposure, with subsequent recovery to baseline levels for three of four irradiated subjects. For the 6,0 Gy the results indicates an intensification of radiation effects upon the lever press response and the polydipsia at the session occurred 48 hours after exposure. Besides, the subjects on fixed interval schedule (FI 60 s) showed greater decrements on both measures than that on fixed time schedule (FT 60 s). The results of the present experiment reproduce the operant behavior literature data, and extend the effects of ionizing radiation to adjunctive behaviors. These results also suggest the occurrence of an interaction between the operant and the adjunctive behavior modulating the effects of ionizing radiation. Keywords: Ionizing radiation; schedule-induced polydipsia.