Early maternal separation and chronic variable stress as adults differentially affect Fos expression in the anterodorsal thalami nuclei.

The present study examined the participation of the anterodorsal thalamic nuclei (ADTN) in mediating the long-term effects of early maternal separation on the stress/hypothalamic-pituitary-adrenal axis response of adult animals. The study measured Fos and glucocorticoid receptor immunoreactivity (GR-ir) in the ADTN of maternally separated female rats subsequently exposed to variable chronic stress. Maternal separation increased the number of neurons immunoreactive to Fos in the ADTN of chronically stressed adult rats. GR-ir was absent in the ADTN. Linking these results with previous endocrine evidence led the authors to propose a dual role of these nuclei. Maternal separation and chronic stress enhance the neuronal activity of the ADTN, nevertheless it is not regulated, at least directly, via GR.