Serum Prolactin and Dehydroepiandrosterone Concentrations During the Summer and Winter Hair Growth Cycles of Mink (Mustela Vison)

In a study conducted 25 years ago, researchers examined the effects of prolactin (PRL) and dehydroepiandrosterone (DHEA) on the hair growth cycles of mink. They found that increasing PRL levels with haloperidol (HAL) could induce the summer hair growth cycle earlier than in control animals, while melatonin (MEL) inhibited PRL and prevented summer hair growth. In the fall, HAL also induced the winter hair growth cycle earlier, but the fur lacked underhair fibers. MEL, on the other hand, initiated winter hair growth four weeks earlier than in controls. Adrenalectomy (ADX) led to an earlier start of both summer and winter hair growth cycles and counteracted the effects of HAL and MEL. Serum DHEA levels did not change during the onset of hair growth cycles, although MEL increased DHEA levels at certain times. The study concluded that changes in serum levels of DHEA and PRL are not necessary for the onset of hair growth cycles in mink, suggesting that metabolites of these hormones might influence other aspects of hair growth.