Effects of photoperiod on circadian clock genes in skin contribute to the regulation of hair follicle cycling of Inner Mongolia white cashmere goats.

This study investigated how the effects of photoperiod on circadian clock genes in the skin contribute to the regulation of hair follicle cycling of Inner Mongolia white cashmere goats. Twenty-four female (non-pregnant) Inner Mongolia white cashmere goats aged 1 - 1.5 years old with similar live weights (mean, 20.36 ± 2.63 kg) were randomly allocated into two groups: a natural daily photoperiod group (NDPP group:10 - 16 hr Light, n = 12) and a short daily photoperiod group (SDPP group: 7 hr Light:17 hr Dark, n = 12). All goats were housed in individual pens from May 15 to October 15, 2015 and were fed the same diets. We detected the mRNA expression of brain and muscle arnt-like protein-1 (Bmal1), circadian locomotor output control kaput (Clock), cryptochrome-1 (Cry1), period homolog-1 (Per1) and Rev-erbα genes in the goat skin. ANOVA revealed a significant 24 hr (10:00 hr, 14:00 hr, 18:00 hr, 22:00 hr, 02:00 hr, 06:00 hr, 10:00 hr) variation between the SDPP and NDPP groups for three months (July, September, and October). In summary, the current results confirm that an intrinsic oscillating molecular clock exists in goat skin, and that the clock is important for potential timing mechanisms at the anagen phase of hair follicles, which would contribute to the regulation mechanisms of hair follicle cell proliferation.