Differential sensitivity to amphetamine’s effect on open field behavior of psychosocially stressed male rats
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Studies of socially housed rodents have provided significant information regarding the mechanisms of stress and of stress-related disorders.
Since psychosocial stress is known to alter the functional activity of dopaminergic system, we employed amphetamine (AMP) to evaluate the involvement dopamine in mediating the behavioral consequences of psychosocial stress.
Male rats housed two per cage were designated as dominant (DOM) or subdominant (Sdom) based on initial evaluations of agonistic behaviors and body weight changes. Diad-housed rats and a group of single-housed (SiH) rats were tested in an open field after injections of saline or amphetamine (0.9 or 2.7 mg/kg IP) prior to and again while diad-housing.
Compared to future DOM rats, saline-injected future Sdom rats entered the open field center less frequently, spent less time in rearing behavior and groomed less. At the pre-diad test AMP treatment elevated locomotor activity of all rats, while stimulation of center entries was more marked in future DOM rats. At the diad test, AMP’s locomotor stimulant effect was evident in all experimental groups with DOM rats showing higher effects compared to Sdom and SiH rats. Amphetamine’s stimulation of center entries in DOM rats was similar to the pre-diad test, but it was diminished in Sdom rats, while stimulation of rearing behavior was most evident in diad-housed rats.
The dopaminergic system modulates the psychosocial stress-induced differences in explorative and emotional behaviors. Furthermore, behavioral traits like frequency of grooming behavior and of center entries were predictive of future hierarchical status.
KeywordsRank status Open field behavior locomotor behavior Grooming behavior Rearing behavior
This research was supported in part by funds from the National Institute of Alcoholism and Alcohol Abuse, Grant 1RO1AA10124 and the Center of Alcohol Studies.
- Burke AR, Renner KJ, Forster GL, Watt MJ (2010) Adolescent social defeat alters neural, endocrine and behavioral responses to amphetamine in adult male rats. Brain Res 1352:147–56Google Scholar
- Lucas LR, Celen Z, Tamashiro KL, Blanchard RJ, Blanchard DC, Markham C, Sakai RR, McEwen BS (2004) Repeated exposure to social stress has long-term effects on indirect markers of dopaminergic activity in brain regions associated with motivated behavior. Neuroscience 124:449–457PubMedCrossRefGoogle Scholar
- Miczek KA, Yap JJ, Covington HE 3rd (2008) Social stress, therapeutics and drug abuse: preclinical models of escalated and depressed intake. Pharmacol Ther 120:102–28Google Scholar
- Zelena D, Haller J, Halász J, Makara GB (1999) Social stress of variable intensity: physiological and behavioral consequences. Brain Res Bull 48:297–302Google Scholar