EFFECTS OF DOCA PRETREATMENT ON NEURONAL SENSITIVITY AND CELL RESPONSIVENESS TO ANGIOTENSIN-II, IN THE BED NUCLEUS OF THE STRIA TERMINALIS IN THE RAT

A previous study has shown that DOCA pretreatment altered the responsi veness of neurons to microiontophoretic administration of angiotensin II (AII) and aldosterone (Aldo). This result coincided with an increas e in activity in the septo-preoptic region and a decrease in activity of the central nucleus of the amygdala. The latter region is anatomica lly linked to the bed nucleus of the stria terminalis (BNST). Single u nit activity was recorded in the BNST in response to iontophoretic app lication of AII, non-peptide AII-receptor antagonists or Aldo in DOCA- pretreated and in non-pretreated rats. DOCA-pretreatment significantly decreased the responsiveness to AII (28 cells (18.5%) vs. 8 cells (14 .0%) u = 0.018 for excitation and 3 cells (8.6%) vs. 0 cells 0%, II = 0.011 for inhibition, P < 0.05) and to Aldo (24 cells (21.4%) vs. 4 ce lls (10.2%), u = 0.026 for excitation, and 3 cells (2.6%) vs. 0 cells, u = 0.009 for inhibition, P < 0.05) of the neurons localised in the B NST. A significant decrease was found in the inhibitory responses to i ontophoretic application of losartan, an AII type-1 receptor (AT-1) an tagonist (u = 0.042, P < 0.05). No significant differences were record ed with iontophoretic application of PD 123319, a specific AII-type-2 (AT-2) receptor antagonist. Therefore AT-1 receptors are likely respon sible for the decreased responsiveness of the BNST correlated with the decrease in the activity within the amygdala.