Conspecific odor preferences of male albino rats are reversed by intracerebral 6-hydroxydopamine.

The odor of pine shavings from the nest of a female and her litter attracted sexually experienced male Sprague-Dawley rats tested in a two-choice situation. The preference persisted after surgery in controls treated with bilateral intracerebral injections of saline-ascorbic vehicle into the vicinity of the ascending noradrenergic bundle. In contrast, 7 out of 8 animals receiving bilateral injections of the neurotoxin 6-hydroxydopamine (6-OHDA), preferred the odor of clean pine to pine nest odor after surgery, indicating preference reversal. 6-hydroxydopamine also reduced olfactory cortex norepinephrine (NE) concentrations by 85%. Pretreatment with intracerebral injection of amphetamine, a catecholamine uptake inhibitor and releaser, prevented 6-OHDA-induced preference reversal in 7 out of 8 animals and limited NE reduction to 38% of concentrations measured in amphetamine-pretreated vehicle-injected controls. The data implicate central NE in the modulation of responses to conspecific odors.