The Journal of Nutrition Vol. 127 No. 5 May 1997, pp. 765-769
Copyright ©1997 by the American Society for Nutritional Sciences

Analgesic Response to Stress Is Reduced in Perinatally Undernourished Rats

Manuscript received 10 May 1996. Initial reviews completed 6 June 1996. Revision accepted 9 December 1996.

Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Agencia Postal 4, C.C. 61, 5000 Córdoba, Argentina

Stress-induced analgesia was evaluated in adult rats submitted early in life to a protein deprivation schedule. Rats were undernourished with a hypoproteic diet containing 80 g casein/kg diet from d 14 of gestation until 50 days of age. Rats were thereafter fed a balanced nonpurified diet until 140 days of age, when they were exposed to two stressors: forced swimming and acute restraint, after which the analgesic response was evaluated. In addition, the analgesic response induced by different 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 stress situations. However, when the analgesic response induced by different morphine doses (1, 2, 4 and 8 mg/kg, s.c.) was assessed, a significantly higher response occurred in undernourished rats compared to control rats. This lower stress-induced analgesia in undernourished rats may account for the behavioral alterations attributed to early undernutrition.