Effect Of Expression Of Hair Follicle Related-growth Genes On The Growth Of Hair Follicle In Sheep

1. Effect of plucking or shaving on sheepskin gene expressionIn order to investigate effect of expression of hair follicle related-growth genes on the modulation of hair follicle growth in sheep, Chinese Merino sheep were selected for the experiments. The levels of mRNA encoding GHR, IGF-1, IGF-1R, KAP3.2 and KAP6-1 were measured in plucked sheepskin or shaved sheepskin at day 0,3,6,9,12 and 50 respectively by relative quantitative reverse transcription polymerase chain reaction (RT-PCR) using beta-actin as an internal standard. The results were as follows: Compared with control, the expression of hair follicle related-growth genes had some fluctuation in plucked or shaved sheepskin. In plucked sheepskin, there were significant decreases in expression of GHR, IGF-1, KAP3.2, KAP6-1 at day 3 and IGF-1R at day 6 but no changes longer than 6 days. In shaved sheepskin, only the expression of IGF-1 increased significantly (6 days), while that of GHR, IGF-1R, KAP3.2 and KAP6-1 had no evident changes at any stage. These results may be correlated with the degree of trauma and the integrality of dermal papilla being destroyed by plucking or shaving.2. Effect of IGF-1 on gene expression in varied sheepskinThirty-six Chinese Merino sheep were selected and divided into six groups at random. Left and right two side scapular foreparts of each sheep were divided into three areas of being plucked, shaved and untreated, and then the corresponding areas in two sides were plucked and shaved respectively. The cross area of being plucked, shaved and untreated of each sheep in the left side was injected intradermally with 0.5 mL IGF-1 (10ng/mL), while the corresponding areas of being plucked, shaved and untreated in the right side were matched control. Each group was selected at random and sampled in two sides sheepskin of plucked tissues, shaved tissues and control tissues at day 0, 3, 6, 9, 12 and 50 respectively. The expression of mRNA encoding GHR, IGF-1, IGF-1R, KAP3.2 and KAP6-1 were measured in each sample by RT-PCR. The results were as follows:1).In normal sheepskin, the expression of GHR decreased with injection of IGF-1 and no change of IGF-1 and IGF-1R was observed but the expression of KAP3.2 and KAP6-1 increased markedly.2).In plucked sheepskin, the abundance of GHR, IGF-1 and IGF-1R mRNA in IGF-1-injected region was no change but the abundance of KAP3.2 and KAP6-1 mRNA increased significantly. Moreover, the pattern of expression of KAP3.2 and KAP6-1 were similar but the expression peak of KAP3.2 was prior to that of KAP6-1.3). In shaved sheepskin, the levels of IGF-1, KAP3.2 and KAP6-1 mRNA were increased dramati- cally after injection IGF-1, but there had no clear fluctuation of GHR and IGF-1R; likely, the pattern of expression changes of KAP3.2 and KAP6-1 were similar but the expression peak of KAP3.2 was also prior to that of KAP6-1.In general, the expression of hair follicle related-growth genes were decreased by plucking but only the expression of IGF-1 was increased by shaving. The expression of KAP3.2 and KAP6-1 was increased significantly after injection extrinsic IGF-1 and their specific expression order was changed, but no change of IGF-1R was observed. The results indicated that extrinsic IGF-1 acts on hair follicle growth by not IGFs axis but other one.