Long-lasting effect of early handling on the peripheral benzodiazepine receptor

The present study determined the impact of early handling (EH) in rats on b ehavioral response to environmental stress and on peripheral benzodiazepine receptor (PBR) binding characteristics (B-max and K-d) in various organs. The behavioral consequences of EH in rats were expressed as increased explo ratory activity in an open-field paradigm, when compared with nonhandled co ntrol rats. These findings are interpreted in terms of decreased emotionali ty. The biochemical consequences of EH, in both male and female rats, were expressed as the upregulation of PER in the adrenal and kidney and the down regulation of gonadal (testis and ovary) PER. It is possible that the long- lasting adrenal and renal changes in PER expression in EH rats may enable b etter regulation of the hypothalamic-pituitary-adrenal axis, renin-angioten sin system, and autonomic nervous system responses to stress in adulthood. The significance of the EH-induced reduction in gonadal PER for gonadal act ivity in adulthood is as yet unclear. (C) 1999 Elsevier Science Inc.