Importance of beta-noradrenergic receptors in the olfactory bulb of sheep for recognition of lambs.

Within a 4-hr period after parturition, the ewe learns the odor of her lamb that will allow later recognition of her offspring from alien lamb. This study investigated the importance of the activation of olfactory bulb (OB) beta-noradrenergic receptors in establishing this olfactory memory. Pregnant ewes (n = 24) were cannulated bilaterally in the OB. Two days before parturition, OB were perfused continuously (10 microliters/hr) with either a solution containing the selective beta-noradrenergic antagonist propranolol (10(-3) M) or vehicle. The results showed that, although 8 of 9 control ewes were still able to bond selectively to their lambs, only 7 of 15 propranolol-treated animals were able to bond (p = .04). These results suggest that activation of beta-noradrenergic receptors in the OB during the period surrounding parturition is required to establish olfactory recognition of the lamb.