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Infant rats depleted of brain dopamine as neonates exhibit normal independent ingestion
1Department of Psychology, Ohio State University, Columbus 43210.
Insights
Early-life dopamine depletion in rats does not impair feeding behaviors. Dopaminergic system development influences ingestive and activational responses in young rats.
Area of Science:
- Neuroscience
- Developmental Biology
- Behavioral Science
Background:
- Striatal dopamine (DA) depletion in adult rats causes severe ingestive deficits.
- Rats depleted of DA on postnatal Day 3 do not show these deficits.
Purpose of the Study:
- To investigate the developmental trajectory of dopaminergic control over ingestive and activational behaviors in rats.
- To determine if early-life DA depletion impairs independent ingestion and behavioral responses.
Main Methods:
- Rats were depleted of striatal DA on postnatal Day 3.
- Ingestive behaviors were assessed via intraoral cannula.
- Behavioral responses to maternal deprivation and dehydration were measured.
- Haloperidol administration was used to assess dopaminergic mediation.
Main Results:
- DA-depleted pups ingested independently as early as 3 days post-depletion.
- Activational and ingestive responses to stimuli were similar in depleted and control pups.
- Haloperidol did not affect behaviors in normal pups at Day 6, but did at Day 12.
- DA-depleted pups at Day 12 still exhibited normal behaviors, unaffected by haloperidol.
Conclusions:
- There is a developmental progression in dopaminergic control of ingestion and activation.
- Near-total striatal DA depletion in early life does not impair these behaviors.
- The developing brain exhibits resilience to DA depletion in specific behavioral domains.
Abstract:
Weanling or adult rats that have sustained near-total depletions of striatal dopamine (DA) on postnatal Day 3 do not exhibit the severe ingestive deficits seen in comparably depleted adults. The present experiments demonstrated that these animals are capable of ingesting independently, via an intraoral cannula, as early as three days after the depletion. Both activational and ingestive responses to maternal deprivation and intracellular dehydration were virtually identical to the responses of control pups. However, these responses may not be entirely dopaminergically mediated at Day 6 since administration of haloperidol failed to attenuate these behaviors in normal pups. When tested on Day 12, DA-depleted pups continued to exhibit normal ingestive and activational behaviors, despite the fact that haloperidol now suppressed these behaviors in both groups of 12-day-old pups. These findings demonstrate that there is a developmental progression of dopaminergic involvement in the control of independent ingestion and the associated activational responses, yet a near-total depletion of striatal DA is not sufficient to impair the expression of these behaviors.