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Behavioural effects of early undernutrition and restricted maternal care in the rat
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M.e,n
Bebavioural effects of early undernutrition and restricted maternal care in the rat S L O B AND CATHERINE E. S N O W - - Department oJ" Endocrinology, Growth and Reproduction, Rotterdam Medical FaculO,, Rotterdam (The Netherlands;
A. K o o s
Previous stu&es o f the effects ol early undernutritlon on behav]our m adult rats have c o n f o u n d e d underfeeding with alterations in the ammals' early social environment, e g. maternal d e p n v a t m n or membership of a large litter. In the present experiments litter size was kept to a standard o f 8 pups while an attempt was made to assess the behav]oural effects o f early u n d e r n u t r m o n m conjunction with either continuous or restricted maternal care. F o o d deprivation from day I until day' 25 was achmved by placing male and female rat pups (Wlstar, A m s t e r d a m - R stock) for 12 h/day (Exp. l) with a foster mother who would display all maternal behavlours except lactation, or (Exp. 2) m an incubator (relative humidity 70-80 °,,, temperature 29 "C). In both experiments control pups o f both sexes remained with the lactating mother t h r o u g h o u t the day' and were handled the same a m o u n t as food-deprived rats. Beginning on day 75, the animals were tested for exploratory behavmur and emotlonahty in the open field, food motivated learning ability in the H e b b - W l l h a m s ma2e, shock motivated learning ability' in the T h o m p s o n box, and basehne locomotor activity In a residential plus maze. In both experiments the food deprivation regimen produced animals whJc,h were significantly hghter and smaller than control rats at the age when behav~oural tests were begun. Eye opening in both sexes and vaginal opening m females wele sigmficantl2y retarded following food deprlvatmn. In contrast to previous findings. food-deprived male and female rats in both experiments did not enter m o r e squares or produce more boluses in the open field, nor did they make more errors m the Hebb-Wflliams maze. However, incubator food-deprived animals made more errors m the T h o m p s o n box. Food-deprived animals in both experiments made more excursions per night m the residential plus maze than control rats, with the exception o f incubator-reared .~emales whmh were not more active than control females. These findings suggest that in the rat early undernutritlon per se (a) has no lasting effect on learning ability or emotlonahty, and (b) causes a permanent increase in l o c o m o t o r activity irrespective of the availability o f full-time maternal care dE'ring the period o f u n d e r n u t r m o n .
M.e,n
Bebavioural effects of early undernutrition and restricted maternal care in the rat S L O B AND CATHERINE E. S N O W - - Department oJ" Endocrinology, Growth and Reproduction, Rotterdam Medical FaculO,, Rotterdam (The Netherlands;
A. K o o s
Previous stu&es o f the effects ol early undernutritlon on behav]our m adult rats have c o n f o u n d e d underfeeding with alterations in the ammals' early social environment, e g. maternal d e p n v a t m n or membership of a large litter. In the present experiments litter size was kept to a standard o f 8 pups while an attempt was made to assess the behav]oural effects o f early u n d e r n u t r m o n m conjunction with either continuous or restricted maternal care. F o o d deprivation from day I until day' 25 was achmved by placing male and female rat pups (Wlstar, A m s t e r d a m - R stock) for 12 h/day (Exp. l) with a foster mother who would display all maternal behavlours except lactation, or (Exp. 2) m an incubator (relative humidity 70-80 °,,, temperature 29 "C). In both experiments control pups o f both sexes remained with the lactating mother t h r o u g h o u t the day' and were handled the same a m o u n t as food-deprived rats. Beginning on day 75, the animals were tested for exploratory behavmur and emotlonahty in the open field, food motivated learning ability in the H e b b - W l l h a m s ma2e, shock motivated learning ability' in the T h o m p s o n box, and basehne locomotor activity In a residential plus maze. In both experiments the food deprivation regimen produced animals whJc,h were significantly hghter and smaller than control rats at the age when behav~oural tests were begun. Eye opening in both sexes and vaginal opening m females wele sigmficantl2y retarded following food deprlvatmn. In contrast to previous findings. food-deprived male and female rats in both experiments did not enter m o r e squares or produce more boluses in the open field, nor did they make more errors m the Hebb-Wflliams maze. However, incubator food-deprived animals made more errors m the T h o m p s o n box. Food-deprived animals in both experiments made more excursions per night m the residential plus maze than control rats, with the exception o f incubator-reared .~emales whmh were not more active than control females. These findings suggest that in the rat early undernutritlon per se (a) has no lasting effect on learning ability or emotlonahty, and (b) causes a permanent increase in l o c o m o t o r activity irrespective of the availability o f full-time maternal care dE'ring the period o f u n d e r n u t r m o n .