Effect of ageing on extracellular ascorbate concentration in rat brain

Area of Science:

• Neuroscience
• Biochemistry

Background:

• Extracellular ascorbate (AA) is a crucial antioxidant in the brain.
• Ageing affects neurotransmitter systems and cellular functions.

Purpose of the Study:

• To investigate the impact of ageing on extracellular ascorbate concentration in the rat brain.
• To examine age-related changes in ascorbate and dopamine (DA) release in response to stimuli.

Main Methods:

• In vivo voltammetry using electrochemically pretreated carbon fibre electrodes.
• Recordings from the nucleus accumbens, caudate putamen, and frontal cortex of Sprague-Dawley rats of different ages (3, 6, and 18 months).
• Administration of ethanol and induction of terminal anoxia to assess brain responses.

Main Results:

• Basal extracellular ascorbate concentration significantly decreased with age, with 18-month-old rats showing less than 10% of the AA signal of 3-month-old rats.
• Ethanol administration and anoxia induced less pronounced ascorbate release in older rats compared to younger ones, particularly in dopamine-rich areas.
• Increased extracellular dopamine release in the nucleus accumbens and caudate putamen was observed, followed by a reversal of the ascorbate signal, suggesting dopamine-dependent autoxidation.

Conclusions:

• Brain ascorbate levels decline with age in rats.
• Ageing impairs the brain's ability to release and respond to ascorbate under physiological stress.
• These findings suggest a significant role for brain ascorbate in the ageing process and its associated neurochemical changes.