Sympathetic response to exercise in various tissues with advancing age

Area of Science:

• Physiology
• Neuroscience
• Aging Research

Background:

• Sympathetic nervous system activity, regulated by norepinephrine (NE), plays a crucial role in physiological responses to stress, including exercise.
• Age-related changes in sympathetic function can impact cardiovascular and metabolic health.
• Understanding how aging affects norepinephrine turnover (NEt) is vital for comprehending exercise physiology in older populations.

Purpose of the Study:

• To investigate age-related alterations in norepinephrine turnover (NEt) across different tissues at rest and during various exercise intensities.
• To compare NEt in young (6-month-old) and aged (25-month-old) Fischer 344 rats.

Main Methods:

• Norepinephrine turnover (NEt) was assessed in young and aged Fischer 344 rats.
• NEt measurements were conducted at rest, during 30 minutes of submaximal exercise, and during maximal exercise.
• The method involved administering alpha-methyl-p-tyrosine, a tyrosine hydroxylase inhibitor, to determine NEt.

Main Results:

• Resting norepinephrine levels decreased with age in the heart and liver.
• During submaximal exercise, older rats exhibited significantly higher NEt in the heart, liver, and adrenal glands compared to younger rats.
• The response of NEt to maximal exercise varied between age groups and tissues.

Conclusions:

• Aging appears to increase sympathetic nervous system activity during exercise stress, as evidenced by elevated NEt in older rats.
• This heightened NEt in aged animals may stem from decreased adrenergic receptor sensitivity or responsiveness.
• These findings highlight the impact of aging on the neurochemical regulation of exercise performance.