Reversible, Sexually Dimorphic Sympathetic Aging: Distal Axon Withdrawal Shaped by Prepubertal Gonadal Influences

Peripheral nerve fibers in skin diminish as animals age, but the extent to which this process varies between sexes and whether it signifies neuronal decay or nerve-muscle communication issues is still up for debate. By studying skin in mice, researchers have discovered that age-related nerve degeneration is indeed more pronounced in adult males.

Despite the fact that the neurons in charge of this process remain unscathed, the decline appears to stem from the loss of distal nerve endings rather than a reduction in neuron count. As animals get older, the connection between nerves and their target, the arrector pili muscle, weakens, particularly in males. Surprisingly, even though aged nerve cells remain sensitive to NGF, a growth factor, boosting NGF levels within the arrector pili muscle can encourage nerve regeneration and hair growth in elderly males.

Genetic and hormonal experiments have revealed that these divergent aging patterns are linked to the presence of male hormones, rather than genetic sex, and can be mitigated by removing the gonads before puberty. In summary, this study demonstrates that age-related nerve degeneration is not only reversible but also influenced by the environment and hormonal factors, particularly in males.