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Aversive stimulation during the stress-hyporesponsive period does not affect the number of corticotroph cells in neonatal male rats

C.E. Aguiar, L.P. Cadore, M.J. Padoin, L.M. Barbosa-Coutinho, A.B. Lucion
1997 Brazilian Journal of Medical and Biological Research  
Immunohistochemistry was used to evaluate the effects of neonatal handling and aversive stimulation during the first 10 days of life on the number of corticotrophs in the anterior lobe of the pituitary of 11-dayold male Wistar rats. Since adult rats handled during infancy respond with reduced corticosterone secretion in response to stressors and with less behavior inhibition in novel environments, we assumed that neonatal stimulation could affect pituitary morphology during this critical period
more » ... his critical period of cell differentiation. Three groups of animals were studied: intact (no manipulation, N = 5), handled (N = 5) and stimulated (submitted to 3 different aversive stimuli, N = 5). The percentage of ACTH-immunoreactive cells in the anterior lobe of the pituitary (number of ACTH-stained cells divided by total number of cells) was determined by examining three slices per pituitary in which a minimum of 200 cells were counted by two independent researchers. Although animals during the neonatal period are less reactive to stresslike stimulation in terms of ACTH and corticosterone secretion, results showed that the relative number of ACTH-stained cells of neonatal handled (0.25 ± 0.01) and aversive stimulated (0.29 ± 0.03) rats was not significantly different from intact (0.30 ± 0.03) animals. Neonatal stimulation may have a differential effect on the various subpopulations of corticotroph cells in the anterior pituitary. Correspondence A.B. Lucion Departamento de Fisiologia ICBS, UFRGS Rua Sarmento Leite, 500 90050-170 Porto Alegre, RS Brasil
doi:10.1590/s0100-879x1997001200013 pmid:9686167 fatcat:ezk4o6xhfrbsjo4526dwlv6e6i