Nisoxetine infusion into the olfactory bulb enhances the capacity for malerats to identify conspecifics

In the present report, the norepinephrine uptake inhibitor nisoxetine as we ll as a cocktail of nisoxetine and the alpha -adrenergic receptor antagonis t phentolamine were infused unilaterally into the olfactory bulb during mic rodialysis to assess their effects upon the capacity of male rats to identi fy conspecifics. A social discrimination test was conducted while simultane ously measuring olfactory bulb norepinephrine output in the dialysate befor e. during, and after behavioral testing. Nisoxetine significantly increased norepinephrine levels in the olfactory bulb compared with the Ringer's sol ution control group. Following such increases in olfactory bulb norepinephr ine. identification responses were enhanced compared with that observed in the Ringer's control. In the presence of phentolamine. nisoxetine elevated olfactory bulb norepinephrine to levels similar to that obtained in the nis oxetine alone group. however. investigatory responses directed to the consp ecifics indicated an absence of identification capacity similar to that obs erved in the Ringer's control group, These results reveal a direct link bet ween norepinephrine transmission in the olfactory bulb and enhanced identif ication via its activation of postsynaptic alpha -adrenergic receptors. The se results also show that inhibition of norepinephrine uptake may represent an important mechanism involved with the enhancement of social identificat ion and suggest a possible novel effect for the antidepressant nisoxetine. (C) 2001 IBRO. Published by Elsevier Science Ltd. All rights reserved.