EFFECTS OF EARLY PROTEIN-MALNUTRITION AND ENVIRONMENTAL STIMULATION UPON THE REACTIVITY TO DIAZEPAM IN 2 ANIMAL-MODELS OF ANXIETY

In order to investigate the effects of early protein malnutrition and environmental stimulation upon the response to the anxiolytic properti es of diazepam, two animal models of anxiety (elevated plus-maze and l ight-dark transition tests) were used. Rats were malnourished by feedi ng their darns a 6% protein diet during the lactation period (0-21 day s of age) while well-nourished controls received a 16% protein diet. F rom 21 to 70 days of age all rats received a balanced lab chow diet. E nvironmental stimulation consisted of 3-min daily handling from birth to 70 days of age. Additional stimulation was provided from 21 to 70 d ays of age by rearing the rats in an enriched living cage. Eight group s of rats were studied in a 2 (malnourished or well-nourished) x 2 (st imulated or nonstimulated) x 2 (diazepam or vehicle) design. At 70 day s of age, independent groups of rats treated with diazepam (2.5 mg/kg, IP) or vehicle were submitted to testing in the elevated plus-maze or light-dark transition procedures. The results showed that both diazep am and environmental stimulation reduced anxiety in the elevated plus- maze; stimulation changed the anxiolytic response to diazepam and the two diet conditions altered differentially the response to both pharma cological and stimulation procedures. These results suggest that envir onmental stimulation can affect differentially the behavioral response of malnourished and well-nourished rats treated with diazepam.