Allosteric modulation of the GABA(A) receptor in rat hypothalamus by somatostatin is altered by stress

1. This autoradiographic study was conducted to investigate somatostatin mo dulation of GABA(A) receptor binding in hypothalamic structures of immobili zation-stressed rats. 2. GABA(A) receptor binding was labelled with [S-35]-t-butylbicyclophosphor othionate (TBPS), which binds in or near the chloride channel. 3. Several structures of the rat hypothalamus (i.e. the peri- and paraventr icular nuclei) display an increase in [S-35]-TBPS binding as well as an alt eration of the modulatory effect of somatostatin on the GABA(A) receptor co mplex under stress. Furthermore, these results demonstrate for the first ti me that somatostatin is particularly effective in modifying [S-35]-TBPS bin ding to the GABA(A) receptor in rat hypothalamus.