Melatonin promotes secondary hair follicle development of early postnatal cashmere goat and improves cashmere quantity and quality by enhancing antioxidant capacity and suppressing apoptosis

Abstract

Development of secondary hair follicles in early postnatal cashmere goats may be adversely affected by reactive oxygen species which cause oxidative stress. Because melatonin is a potent antioxidant and scavenger of free radicals, this study explored the effects of melatonin on secondary hair follicle development and subsequent cashmere production. It was found that the initiation of new secondary follicles in early postnatal Inner Mongolian cashmere goats of both melatonin‐treated and control goats occurred in the first 10 weeks of age. Melatonin promoted the initiation and maturation of secondary follicles and increased their population. Importantly, the beneficial effect of melatonin on secondary follicle population remained throughout life. As a result, melatonin increased cashmere production and improved its quality in terms of reduced fiber diameter. The mechanisms underlying the role of melatonin on secondary follicle development included the enhancement of activities of antioxidant enzymes, for example, superoxide dismutase and glutathione peroxidase (GSH‐Px), elevated total antioxidant capacity, and upregulated anti‐apoptotic Bcl‐2 expression and downregulated expression of the pro‐apoptotic proteins, Bax and caspase‐3. These results reveal that melatonin serves to promote secondary hair follicle development in early postnatal cashmere goats and expands our understanding of melatonin application in cashmere production. Melatonin treatment led to an increase in both the quantity and quality of cashmere fiber. This increased the textile value of the fibers and provided economic benefit.

Effects of melatonin administration to cashmere goats on cashmere production and hair follicle characteristics in two consecutive cashmere growth cycles

“…In the current study, the population of primary hair follicles in the skin was the same for both melatonintreated and control cashmere goats and did not change over two consecutive cashmere growth cycles. This helps to con rm the view that the population of primary hair follicles in cashmere goats is established at birth and is not affected subsequently by treatment of adult cashmere goats with exogenous melatonin [8,[17][18][19]. In the case of secondary hair follicles, previous studies have also shown no effect of melatonin treatment on their total population, and thus no effect on S:P ratio [20,21].…”

“…Twenty-four female Inner Mongolian Cashmere goats were randomly allocated to two groups (n = 12): melatonin-treated (Melatonin) and control (Control) that were balanced for age, live weight and cashmere yield. Capsules containing melatonin were subcutaneously inserted behind an ear in cashmere goats on April 30 and June 30, 2016 at a dosage of 2 mg/kg live weight, which is based on our previous studies [3,8]. The melatonin implants were purchased from Kangtai Biotechnology Co., Ltd (Beijing, China) and can release melatonin sustainably for two months.…”

“…Cashmere bre staple length was measured with a ruler as described by Yang [8] and cashmere bre diameter was measured by an optical microscopic projection method as described by Duan [3]. Cashmere bre density was determined by measuring the active secondary hair follicle density in the skin obtained on September when the active secondary hair follicle numbers reach their seasonal maximum and agree with the cashmere bre numbers.…”

“…In this study, primary hair follicles and secondary hair follicles were evaluated separately. They are easily distinguished from each other based on their speci c characteristics as described by Yang [8]. Hair follicles were classed as active or inactive according to their size, shape, staining and the presence or absence of an inner root sheath.…”

Single-cell sequencing reveals the intermediate cell state and function of dermal papilla cells in the hair follicle cycle of cashmere goats

“…The hair of cashmere goats is divided into primary hair (guard hair) and secondary hair (ground hair or cashmere) [19,20]. The cashmere quality of cashmere goats has a signi cant relationship with the secondary hair follicles [21], but the speci c regulatory mechanism has not been fully explained. Therefore, the mechanism of action of DP cells on cashmere growth needs to be elucidated.…”