ANALGESIC RESPONSE TO STRESS IS REDUCED IN PERINATALLY UNDERNOURISHEDRATS

Stress-induced analgesia was evaluated in adult rats submitted early i n life to a protein deprivation schedule. Rats were undernourished wit h a hypoproteic diet containing 80 g casein/kg diet from d 14 of gesta tion until 50 days of age. Rats were thereafter fed a balanced nonpuri fied diet until 140 days of age, when they were exposed to two stresso rs: forced swimming and acute restraint, after which the analgesic res ponse was evaluated. In addition, the analgesic response induced by di fferent morphine doses was determined in another group of rats. Basal latency was not different in deprived and control rats. Undernourished rats presented a significantly lower analgesic response in both stres s situations. However, when the analgesic response induced by differen t morphine doses (1, 2, 4 and 8 mg/kg, s.c.) was assessed, a significa ntly higher response occurred in undernourished rats compared to contr ol rats. This lower stress-induced analgesia in undernourished rats ma y account for the behavioral alterations attributed to early undernutr ition.