Effects of undernutrition during suckling and of post-training beta-endorphin administration on avoidance performances of adult rats.
1. The effects of undernutrition during suckling and of post-training beta-endorphin administration on avoidance task were investigated in adult rats. 2. Young rats were undernourished from delivery until weaning (21 days) by feeding their mothers a diet containing 8% protein (w/w). Mothers of well-nourished rats were fed a 20% protein diet. After weaning, both groups of rats were fed a 20% protein diet until 90-120 days of age, when they were subjected to behavioral sessions. 3. Acquisition was measured in training sessions and retention in test sessions 24 h after training. Beta-endorphin or saline (control) was injected ip immediately after training. Rats were subjected to shuttle and step-down inhibitory avoidance sessions using footshock of 0.2 or 0.8 mA intensity. 4. Undernutrition during suckling caused hyperreactivity to 0.2 mA footshocks. Beta-endorphin caused amnesia to shuttle avoidance task only in normal rats trained with 0.8 mA footshocks. In the step-down inhibitory avoidance task, beta-endorphin was amnesic only for normal rats and only for 0.2 mA footshocks. Beta-endorphin was not amnesic in undernourished rats.
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Departamento de Bioquímica, UFRGS, Porto Alegre, RS, Brasil.
Rocha
J B
JB
Mello
C F
CF
Souza
D O
DO
D000818:Animals; D004032:Diet; D004597:Electroshock; D004924:Escape Reaction / Q000187:drug effects / Q000502:physiology*; D005260:Female; D007031:Hypothalamus / Q000378:metabolism; D008297:Male; D008568:Memory / Q000187:drug effects*; D011502:Protein-Energy Malnutrition / Q000150:complications*; D051381:Rats; D011919:Rats, Inbred Strains; D012153:Retention, Psychology / Q000187:drug effects*; D001615:beta-Endorphin / Q000008:administration & dosage* / Q000378:metabolism
D001615:beta-Endorphin