Noradrenaline and neophobia

Lesions of the ascending noradrenergic bundles using the selective neurotoxin 6-hydroxydopamine increased neophobia to a number of novel tastes in rats. These lesions also increased some, but not all, measures of neophobia in novel environments. The results are discussed with reference to a recent hypothesis which suggests that the noradrenergic projections of the locus coeruleus mediate some aspects of fear and anxiety. Contrary to the prediction of this hypothesis, the noradrenergic lesions significantly increased rather than decreased neophobia. While these results point to an involvement of ascending noradrenergic systems in fear, at present the nature of this involvement cannot be specified in detail.