Role of Prolactin in Regulating the Onset of Winter Fur Growth in Mink: A Reconsideration

The study investigated the role of prolactin (PRL) in the onset of winter fur growth (anagen) in mink. It found that melatonin (MEL) reduced PRL levels and induced winter anagen 7 weeks earlier than controls, while haloperidol (HAL) also initiated winter anagen early without altering PRL levels. Adrenalectomy (ADX) and ADX + DHEA treatments led to early winter anagen, but PRL levels remained unchanged. DHEA or Delta(5)-DIOL administration did not affect the timing of winter anagen or PRL levels. The results suggested that reduced PRL levels were not necessary for winter anagen onset and that adrenal glands' inhibitory effects were not mediated by DHEA or its metabolite Delta(5)-DIOL.