Behavioral and hypothalamic-pituitary-adrenal responses to anterodorsal thalami nuclei lesions and variable chronic stress in maternally separated rats

At 3 months old, under variable chronic stress, maternal separation provoked an increase in ambulation in sham and lesioned animals (P < 0.01) but this parameter was not modified by lesion in either non-maternally separated or maternally separated groups. Neither the lesion nor the maternal separation changed the defecation and rearing parameter. Grooming behavior was lower in maternally separated lesioned rats (P < 0.05). Under variable chronic stress maternal separation decreased adrenocorticotrophin hormone in comparison with non-maternally separated (P < 0.001) and the lesion did not alter this response. Regarding corticosterone concentrations, maternal separation did not affect this hormone under variable chronic stress conditions and after the open field test there was an increase of this in both non-maternally separated and maternally separated sham and lesioned (P < 0.001).