RESUMO
BACKGROUND: Early life adverse experience alters adult emotional and cognitive development. Here we assess early life learning about adverse experience and its consequences on adult fear conditioning and amygdala activity. METHODS: Neonatal rats were conditioned daily from 8-12 days-old with paired odor (conditioned stimulus, CS) .5mA shock, unpaired, odor-only, or naive (no infant conditioning). In adulthood, each infant training group was divided into three adult training groups: paired, unpaired or odor-only, using either the same infant CS odor, or a novel adult CS odor without or with the infant CS present as context. Adults were cue tested for freezing (odor in novel environment), with amygdala (14)C 2-DG autoradiography and electrophysiology assessment. RESULTS: Infant paired odor-shock conditioning attenuated adult fear conditioning, but only if the same infant CS odor was used. The (14)C 2-DG activity correlated with infant paired odor-shock conditioning produced attenuated amygdala but heightened olfactory bulb activity. Electrophysiological amygdala assessment further suggests early experience causes changes in amygdala processing as revealed by increased paired-pulse facilitation in adulthood. CONCLUSIONS: This suggests some enduring effects of early life adversity (shock) are under CS control and dependent upon learning for their impact on later adult fear learning.
Assuntos
Envelhecimento , Tonsila do Cerebelo/fisiologia , Condicionamento Clássico/fisiologia , Medo , Memória/fisiologia , Odorantes , Tonsila do Cerebelo/diagnóstico por imagem , Análise de Variância , Animais , Animais Recém-Nascidos , Autorradiografia/métodos , Aprendizagem da Esquiva , Comportamento Animal , Desoxiglucose/metabolismo , Estimulação Elétrica/métodos , Potenciais Evocados/efeitos da radiação , Reação de Congelamento Cataléptica/fisiologia , Masculino , Aprendizagem em Labirinto , Bulbo Olfatório/diagnóstico por imagem , Radiografia , Ratos , Ratos Long-Evans , Tempo de Reação/fisiologia , Tempo de Reação/efeitos da radiaçãoRESUMO
Behavioral transitions characterize development. Young infant rats paradoxically prefer odors that are paired with shock, but older pups learn aversions. This transition is amygdala and corticosterone dependent. Using microarrays and microdialysis, we found downregulated dopaminergic presynaptic function in the amygdala with preference learning. Corticosterone-injected 8-d-old pups and untreated 12-d-old pups learned aversions and had dopaminergic upregulation in the amygdala. Dopamine injection into the amygdala changed preferences to aversions, whereas dopamine antagonism reinstated preference learning.