The role of anterodorsal halami nuclei on the regulation of medullo adrenal function, b cardiac receptors and anxiety responses in maternally deprived rats under stressful conditions

SUÁREZ M.M.; RIVAROLA M.A ; MOLINA S.; LEVIN G., ENDERS J., PAGLINI P.

STRESS

TAYLOR & fRANCIS health sciences

Año: 2004 vol. 7 p. 195 - 203

1025-3890

ABSTRACTMaternal separation can interfere with growth and development of the brain and represents a significant risk factor for adult psycopathology. In rodents, prolonged separation from the mother affects the behavioral and endocrine responses to stress for the lifetime of the animal. The limbic structures such as the anterodorsal thalamic nuclei (ADTN) play an important role in the control of neuroendocrine and sympathetic-adrenal function. In view of these findings we hypothesized that the function of the ADTN may be affected in an animal model of maternal deprivation. To test this hypothesis female rats were isolated 4.5 hours daily, during the three first weeks of life and tested as adults. We evaluated plasma epinephrine (E) and norepinephrine (NE), cardiac adrenoreceptors and anxiety responses to maternal deprivation and variable chronic stress (VCS) in ADTN-lesioned rats. Thirty days after ADTN lesion, in non-maternally deprived animals basal plasma NE concentration was greater and cardiac b-adrenoreceptors density was lower than that in sham-lesioned group. Maternal deprivation (MD) induced a significant increase in basal plasma NE concentration, which was greater in lesioned rats, and cardiac b-adrenoreceptors density was decreased in lesioned rats. After VCS plasma catecholamine was much greater in non-maternally deprived rats than in maternally- deprived rats; and a decrease of cardiac b-adrenoreceptors density was decreased by VCS in both maternally-deprived and non-deprived rats, but more so in non-deprived rats, and further decreased by the ADTN lesion. compared to unstressed rats and to sham-lesioned rats. In the plus maze test, the number of open arm entries was greater in the maternally deprived and in the stressed rats. Thus, sympathetic-adrenal medullary activation produced by VCS was much greater in non-deprived rats, and was linked to a down regulation of myocardial b-adrenoceptors. The ADTN are not responsible for the reduced catecholamine responses to stress in maternally deprived rats. Maternal deprivation or chronic stress also induced a long-term anxiolytic effect, which was also not affected by ADTN lesion.