THE SEPTUM AND THE HIPPOCAMPUS DIFFERENTIALLY MEDIATE ANXIOLYTIC EFFECTS OF R(-8-OH-DPAT())

Infusing the 5-HT1A receptor agonist R(+)-8-OH-DPAT into the septum or hippocampus reduced the fear responses of rats differentially in the elevated plus-maze and shock-probe burying tests, two rat models of an xiety. Intra-septal infusions of R(+)-8-OH-DPAT (5 and 10 mu g) produc ed dramatic reductions in rat burying behavior in the shock-probe test , whereas it did not alter rat open-arm activity in the plus-maze test , across a wide range of doses (0.1, 0.25, 5 and 10 mu g). Conversely, intra-hippocampal infusions of R(+)-8-OH-DPAT (0.1 and 5 mu g/side) p roduced substantial increases in open-arm activity in the plus-maze te st, but did not alter rat burying behavior in the shock-probe test. Th ese dissociations suggest that 5-HT1A receptors in the septum and hipp ocampus exert parallel but distinct control over different fear reacti ons. (C) Rapid Science Ltd.