Harstine B R, Cruppe L H, Abreu F M, Utt M D, Cipriano R S, Lemes A, Premanandan C, DeJarnette J M, Day M L
J Anim Sci. 2017 Apr;95(4):1669-1679. doi: 10.2527/jas.2016.1067.
In prepubertal bulls, FSH facilitates testis maturation and a transient proliferation of Sertoli cells. Two experiments examined the effects of exogenous FSH on hormone secretion and testis development in Angus bulls. Exogenous FSH treatment consisted of an intramuscular injection (i.m.) of 30 mg FSH (Folltropin-V) in a 2% hyaluronic acid solution (FSH-HA). In Exp. 1, bulls (50 ± 6.5 d of age) received either FSH-HA ( = 5) or saline (control; = 5) on d 50 and 53.5. Blood samples were collected via jugular venipuncture to assess FSH concentrations every 6 h for 24 h after treatment and every 12 h until 84 h. After each treatment, peripheral FSH concentrations were greater ( < 0.05) in the FSH-HA-treated bulls than in the control bulls 6 h after treatment and tended to be greater ( ≤ 0.08) 12 h after treatment. The FSH concentration from 18 to 84 h after treatment did not differ between treatments. In Exp. 2, bulls were treated with FSH-HA ( = 11) or saline (control; = 11) every 3.5 d from 35 to 91 ± 2 d of age. Blood samples were collected before each treatment to quantify FSH, testosterone, and activin A concentrations. Scrotal circumference (SC) and BW were measured weekly. Bulls were castrated at 93 ± 2 d of age. Seminiferous tubule diameter, testis composition, and the number of Sertoli cells per tubule cross section (GATA-4 positive staining) were determined from fixed and stained histological sections. Follicle-stimulating hormone concentrations within the FSH-HA-treated bulls increased ( < 0.05) on d 70 from prior sampling and remained elevated. The FSH concentration did not differ between treatments from 35 to 66.5 d of age but were greater ( < 0.05) in the FSH-HA-treated bulls than in the control bulls from 70 to 91 d of age. Serum concentration of activin A on d 35, 70, and 91 did not differ between treatments. The FSH-HA and control bulls did not differ ( > 0.1) in BW, SC, testis weight, testis volume, percent of parenchyma composed of tubules, tubule diameter, and concentration of testosterone. The number of Sertoli cells per tubule cross section was greater in the FSH-HA-treated bulls than in the control bulls (33.35 ± 0.9 vs. 28.27 ± 0.9 cells; ˂ 0.05). In summary, the FSH-HA treatment from 35 to 91 d of age resulted in increased endogenous FSH from 70 to 91 d and increased numbers of Sertoli cells at 93 d of age. Exogenous FSH altered endocrine mechanisms regulating endogenous FSH secretion and augmented Sertoli cell proliferation in young bulls, but this effect was apparently not caused by increased activin A concentration in the FSH-HA-treated bulls.
在青春期前的公牛中，促卵泡素（FSH）促进睾丸成熟以及支持细胞的短暂增殖。两项实验研究了外源性FSH对安格斯公牛激素分泌和睾丸发育的影响。外源性FSH处理包括在2%透明质酸溶液（FSH-HA）中肌肉注射（i.m.）30mg FSH（Folltropin-V）。在实验1中，公牛（50±6.5日龄）在第50天和53.5天接受FSH-HA（n = 5）或生理盐水（对照；n = 5）。处理后24小时内每6小时通过颈静脉穿刺采集血样以评估FSH浓度，直至84小时每12小时采集一次。每次处理后，FSH-HA处理的公牛外周FSH浓度在处理后6小时高于对照公牛（P < 0.05），且在处理后12小时有更高的趋势（P≤0.08）。处理后18至84小时的FSH浓度在处理组间无差异。在实验2中，公牛从35至91±2日龄每3.5天接受FSH-HA（n = 11）或生理盐水（对照；n = 11）处理。每次处理前采集血样以定量FSH、睾酮和激活素A浓度。每周测量阴囊周长（SC）和体重（BW）。公牛在93±2日龄时去势。从固定和染色的组织学切片中确定生精小管直径、睾丸组成以及每个小管横截面积的支持细胞数量（GATA-4阳性染色）。FSH-HA处理的公牛中促卵泡素浓度在第70天较之前采样增加（P < 0.05）并持续升高。35至66.5日龄时处理组间FSH浓度无差异，但70至91日龄时FSH-HA处理的公牛FSH浓度高于对照公牛（P < 0.05）。第35、70和91天激活素A的血清浓度在处理组间无差异。FSH-HA组和对照组公牛在体重、阴囊周长、睾丸重量、睾丸体积、由小管组成的实质百分比、小管直径和睾酮浓度方面无差异（P > 0.1）。每个小管横截面积的支持细胞数量在FSH-HA处理的公牛中多于对照公牛（33.35±0.9对28.27±0.9个细胞；P < 0.05）。总之，35至91日龄的FSH-HA处理导致70至91日龄内源性FSH增加以及93日龄时支持细胞数量增加。外源性FSH改变了调节内源性FSH分泌的内分泌机制并增强了年轻公牛支持细胞的增殖，但这种效应显然不是由FSH-HA处理的公牛中激活素A浓度增加所致。
