DEPLETION OF OLFACTORY-BULB NOREPINEPHRINE BY 6-OHDA DISRUPTS CHEMICAL CUE BUT NOT SOCIAL RECOGNITION RESPONSES IN MALE-RATS

In the present experiment, 6-OHDA was infused directly into the olfact ory bulb (OB) to produce a localized neurotoxic lesion. Habituation/di shabituation behavioral tests were then conducted to measure recogniti on responses to chemical cues (urine as a stimulus) and to social stim uli (ovariectomized rat as a stimulus). Infusion of 6-OHDA resulted in a near complete depletion of OB-norepinephrine (NE), whereas it had l ittle effect (15% reduction) on OB dopamine (DA) contents. Nor were an y significant effects on hypothalamic, hippocampal, olfactory tubercle , and corpus striatal NE and DA contents observed. Behaviorally, disha bituation responses to chemical cues were greatly impaired, however th ere was relatively little effect on social behavior dishabituation res ponses. These results demonstrate that 6-OHDA can be used to produce a near complete but localized depletion of OB-NE. This treatment impair s dishabituation responses to chemical cues but not social stimuli ind icating that OB-NE appears necessary for processing of chemical cue, b ut not social memory recognition process.