ABSTRACT
Exploratory behavior and social interaction were investigated in rats that were reared in different social environments following neonatal injection with either water vehicle or the norepinephrine neurotoxin, DSP-4. At weaning, they were placed in a familiar or novel bedding type and were housed in either vehicle control-only, DSP-4-only, or mixed vehicle control and DSP-4 groups for 10 days. They were then observed in three different situations: the home cage, the cage of an unfamiliar rat, and an open field. Compared to rats housed in vehicle control-only or DSP-4-only groups, rats housed in mixed DSP-4 and vehicle control groups showed elevated exploration behavior in the home cage. Also, rats housed in mixed groups in the familiar bedding, but not the novel one, showed abnormally low levels of rearing in an open field test and reduced social interaction with unfamiliar rats. The implications of these results for a new animal model of anxiety are discussed.
Subject(s)
Adrenergic Agents/pharmacology , Benzylamines/pharmacology , Exploratory Behavior/drug effects , Social Behavior , Animals , Brain Chemistry/drug effects , Hydroxyindoleacetic Acid/metabolism , Male , Norepinephrine/metabolism , Rats , Rats, Inbred StrainsABSTRACT
The possibility that variables affecting rats' home-cage odor preferences also influence hoarding behavior was examined. Neonatal male rats were injected SC with the noradrenergic neurotoxin, N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4), or with vehicle. At weaning, rats were assigned to control-only, DSP-4-only, or mixed groups of DSP-4 and control rats. For the next 10 days, half the rats in each social condition were housed in cedar shavings, and remaining rats were housed in pine. Exposure to cedar significantly increased preference for the odor in control-only groups, but not in DSP-4-only or mixed treatment groups. Control-only groups also hoarded significantly more pellets per animal than rats in the other two social conditions. The results suggest that both olfactory adaptation and hoarding can be impaired by either neonatal NE depletion or an abnormal social environment.
