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Fetal and Early postnatal development of adenylate cyclase and cyclic AMP phosphodiesterase activities in rat brain
Insights
Brain cyclic AMP metabolism shows developmental delays in rat offspring during the perinatal phase. Maternal brain shows reduced adenylate cyclase activity, possibly for parturition preparation.
Area of Science:
- Neuroscience
- Developmental Biology
- Biochemistry
Background:
- Cyclic AMP (cAMP) is a crucial second messenger in brain signaling.
- Understanding cAMP metabolism during development is vital for identifying potential disruptions.
Purpose of the Study:
- To investigate the ontogeny of brain cyclic AMP metabolism in rat offspring during late gestation and early postnatal life.
- To examine changes in adenylate cyclase and phosphodiesterase activities and cAMP levels.
- To assess maternal brain changes during gestation.
Main Methods:
- Measurement of brain wet weight, protein, DNA, and RNA concentrations.
- Assay of adenylate cyclase and high and low Km cyclic AMP phosphodiesterase activities.
- Quantification of cyclic AMP concentrations in brain tissue.
Main Results:
- Offspring brain growth parameters showed parallel increases with body weight until postnatal day 4, with perinatal retardation.
- Qualitative changes in adenylate cyclase and high Km phosphodiesterase were similar, while low Km phosphodiesterase increased from fetal day 17 to 19.
- Cyclic AMP concentrations increased mildly, reaching adult levels by day 21 in fetuses. Maternal brain showed reduced adenylate cyclase activity at days 19 and 21 of gestation.
Conclusions:
- Perinatal retardation in offspring cAMP metabolism is likely due to their metabolic state.
- Maternal brain changes suggest a role in endocrine preparation for parturition.
Abstract:
Brain cyclic AMP metabolism was studied in rat offspring at 17, 19 and 21 days of intrauterine life and 0, 1 and 4 postnatal days. Wet weight and protein and DNA and RNA concentrations in brain increased in parallel with body weight until the 4th postnatal day although during the perinatal phase some of these parameters suffered a manifest temporal retardation. In the brain, similar qualitative changes were observed in both adenylate cyclase and high Km cyclic AMP phosphodiesterase activity while the low Km enzyme showed a rise from 17-day fetuses to those of 19 days with no further changes. The increase in cyclic AMP concentration was very mild and the values found in the 21-day fetuses were already similar to those in adults. In the mother's brain a significant reduction in adenylate cyclase activity appeared at 19 and 21 days of gestation. The retardation in the ontogenic development of cyclic AMP metabolism during the perinatal phase in offspring is probably a consequence of their specific metabolic situation while in the mother it may be the result of its endocrine preparation for parturition.