Effects of postnatal stress on dopamine mesolimbic system responses to aversive experiences in adult life.
The effects of postnatal stress on mesolimbic dopamine (DA) functioning in 90-day-old mice were investigated. Postnatal stress consisted of 15 min daily exposure to clean bedding (CB) in the absence of the mother for the first two weeks of life. Controls were daily exposed to home cage bedding (HCB) in the absence of the mother. A single brief (5-10 min) exposure to restraint produced a clear-cut increase in DA metabolites (3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 3-methoxytyramine (3-MT)) in the nucleus accumbens septi (NAS) of adult HCB but not CB mice. Moreover, when tested in an elevated plus maze, CB mice showed more exploration and reduced fearfulness in comparison with HCB mice. Taken together, these results indicate reduced emotional reactivity in adult mice repeatedly stressed during postnatal development. Moreover, HCB mice but not CB mice showed altered behavioral responsiveness to apomorphine following repeated restraint stress (10 daily 120 min) in adult life, although no difference in the behavioral response to either a low or a high dose of apomorphine was observed in adult unstressed mice of the CB and HCB groups. These results indicate that the effects of early experiences on brain DA functioning may not be evident in basal conditions and be revealed only under environmental pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
Cabib
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Istituto di Psicobiologia e Psicofarmacologia, CNR, Roma, Italy.
Puglisi-Allegra
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D'Amato
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D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000375:Aging; D000704:Analysis of Variance; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D004298:Dopamine / Q000031:analogs & derivatives / Q000378:metabolism*; D005260:Female; D006719:Homovanillic Acid / Q000378:metabolism; D008032:Limbic System / Q000254:growth & development / Q000378:metabolism*; D008297:Male; D008426:Maternal Deprivation; D051379:Mice; D009043:Motor Activity / Q000187:drug effects; D009714:Nucleus Accumbens / Q000254:growth & development / Q000378:metabolism*; D012149:Restraint, Physical; D013315:Stress, Psychological / Q000503:physiopathology*
D015102:3,4-Dihydroxyphenylacetic Acid; C001746:3-methoxytyramine; D001058:Apomorphine; D004298:Dopamine; D006719:Homovanillic Acid