Glucocorticoid and mineralocorticoid receptor mRNA expression in squirrel monkey brain

Corticosteroids have been implicated in hippocampal atrophy in patients wit h severe psychiatric disorders, but little is known about receptor expressi on for corticosteroids in human or nonhuman primate brain. Both the glucoco rticoid receptor (GR) and mineralocorticoid receptor (MR) were surveyed in this study of squirrel monkey brain using in situ hybridization histochemis try. Regions of high GR mRNA levels included CA1 and CA2 of hippocampus, de ntate gyrus, paraventricular hypothalamus, lateral geniculate, lateral > me dial amygdala, and cerebellum. Western analysis confirmed that GR immunorea ctivity in squirrel monkey brain tissue most likely reflects the alpha isof orm. Regions of high MR mRNA levels included all hippocampal pyramidal cell fields, dentate gyrus granule cell layer, lateral septum, medial > lateral amygdala, and to a lesser extent, cerebellum. Low levels of MR were also e xpressed in caudate and putamen. Receptor expression for corticosteroids in deep brain structures and the hippocampal formation was similar to that pr eviously reported in rodents, but GR and MR mRNA were expressed at higher l evels in squirrel monkey cerebral cortex. GR expression was evident in all cortical layers, particularly the pyramidal cell-rich layers II/III and V. MII expression was restricted to the more superficial cortical layers, and was only moderately represented in layer V. Laminar patterns were apparent in all regions of cortex for GR expression in squirrel monkeys, but low MR mRNA levels were found in dorsomedial prefrontal cortex (PFC). Different su bregional distributions and distinctive laminar patterns suggest specialize d functions or coordinated interactions between GR and MR mediated function s in primate PFC. (C) 2001 Elsevier Science Ltd. All rights reserved.