Effect of oxygen on ascorbic acid uptake and concentration in embryonic chick brain

Area of Science:

• Developmental Biology
• Biochemistry
• Neuroscience

Background:

• Ascorbic acid (vitamin C) plays a crucial role in cellular functions and antioxidant defense.
• Fetal development involves dynamic changes in oxygen availability and metabolic demands.
• Understanding vitamin C's role in the developing embryo is vital for assessing nutritional and environmental impacts.

Purpose of the Study:

• To investigate the effects of varying oxygen concentrations on ascorbic acid levels and transport in chick embryos (Gallus gallus domesticus).
• To determine how oxidative stress influences ascorbic acid concentration and its uptake in fetal brain cells.
• To elucidate the regulatory mechanisms of ascorbic acid in plasma versus brain during development and hyperoxia.

Main Methods:

• Chick embryos were incubated under normoxic, hypoxic, and hyperoxic conditions.
• Plasma and brain ascorbic acid concentrations were measured at different developmental stages.
• Ascorbic acid transport was assessed using [14C]ascorbic acid uptake assays in isolated brain cells.

Main Results:

• Plasma ascorbic acid peaked mid-gestation and increased with pulmonary respiration onset; brain levels rose earlier and were maintained.
• Exposure to hyperoxia (42% O2) significantly reduced ascorbic acid in both plasma and brain.
• Hyperoxia inhibited saturable and Na(+)-dependent ascorbic acid transport into isolated brain cells.

Conclusions:

• Ascorbic acid concentration changes in response to oxidative stress, supporting its role in detoxifying oxygen radicals in fetal tissues.
• Brain cells exhibit regulatory mechanisms for ascorbic acid, showing less fluctuation than plasma levels under changing oxygen conditions.
• Hyperoxia-induced reduction in cerebral vitamin C may partly result from inhibited cellular ascorbic acid transport.