Cadmium-induced behavioral changes in growing rats.

Sixty growing male albino rats of the ITRC bred colony, weighing 150-160 g (2 months old) , served as subjects. They were housed in stainless steel cages, in groups of ten and maintained on a 12:12 photoperiod (lights on 06.00-18.00 hr) in a temperature controlled (22 •} 2.0•‹) room. Hind Lever Laboratory chow and water were provided ad lib. The animals were divided into two equal groups and the experimental group was administered 0.5 mg Cd2+/kg, i.p., as cadmium acetate (volume of injection 1 m//kg) daily for 21 days. The vehicle (0.9 % NaCl) injected rats served as controls. The animals were weighed weekly and the following behavioral and chemical parameters were measured at the end of the treatment priod. The rats were placed individually in a photoactometer (Techno, India) and after 5 min. acclimation period, the activity counts for 15 min. were recorded. Twelve rats (in batches of 6) from each group were used. The conditioned avoidance behavior was assessed in a pole climbing chamber (Techno, India). Each animal, after a 5 min. habituation in the experimental chamber, was subjected to 50 trials. A trial consisted of the presentation of continuous 90 dB 1500 Hz tone conditioned stimulus (CS) for 10 sec. followed by the unconditioned stimulus (US), a 0.5 mA constant current scrambled foot shock for 10 sec. and a 40 sec. intertrial interval. The tone remained on when the shock was presented. The animals could avoid the shock by climbing the