Whitley N C, Barb C R, Utley R V, Popwell J M, Kraeling R R, Rampacek G B
Animal and Dairy Science Department, University of Georgia, Athens 30602, USA.
Biol Reprod. 1995 Dec;53(6):1359-64. doi: 10.1095/biolreprod53.6.1359.
Follicular phase (FOL; Days 17-19; n = 8), luteal phase (LUT; Days 7-9; n = 6), and ovariectomized (OVX; n = 5) crossbred gilts were used (Day 0 = onset of estrus). Blood samples were collected via jugular vein cannula every 15 min for 2 h the day before pituitary collection. Serum was assayed for insulin-like growth factor (IGF)-I, IGF-I binding proteins (IGFBP), LH, estradiol (E2), and progesterone (P4). Anterior pituitary cells were dispersed, cultured, and challenged on Day 4 of culture (Day 0 = day of seeding) with 10(-7) M GnRH or IGF-I (10(-11), 10(-10), 10(-9), 10(-8), or 3 x 10(-8) M) individually or in combination. Serum E2 and P4 concentrations indicated that the animals were in the appropriate stage of the estrous cycle. Mean serum LH concentrations were greater (p < 0.0004) for OVX animals compared to FOL and LUT animals. Mean serum IGF-I concentrations were lower (p < 0.05) for OVX compared to FOL and LUT animals, while serum IGFBP were not different among animals. Basal LH secretion (control) was greater (p < 0.04) in OVX than in FOL or LUT cultures. Relative to control, 10(-11) M IGF-I increased (p < 0.02) LH secretion in FOL, LUT, and OVX cultures, and this response was greater (p < 0.05) in FOL and OVX than in LUT cultures. Only the 10(-11) M IGF-I enhanced basal LH secretion in LUT cultures. In addition, 10(-10) M IGF-I increased (p < 0.05) LH secretion in OVX cultures, and 10(-10) and 10(-9) M IGF-I stimulated (p < 0.05) LH secretion in FOL cultures, whereas basal LH secretion in all groups was unaffected (p > 0.05) by 10(-8) or 3 x 10(-8) M IGF-I. The GnRH-induced LH secretion was unaltered by IGF-I treatment. Results indicate that in vitro IGF-I treatment increased basal LH secretion, with reproductive status modulating LH response to IGF-I.
选用处于卵泡期（FOL；第17 - 19天；n = 8）、黄体期（LUT；第7 - 9天；n = 6）的杂种母猪以及去卵巢（OVX；n = 5）的杂种母猪（第0天 = 发情开始）。在采集垂体前一天，通过颈静脉插管每15分钟采集一次血样，共采集2小时。检测血清中的胰岛素样生长因子（IGF）-I、IGF-I结合蛋白（IGFBP）、促黄体生成素（LH）、雌二醇（E2）和孕酮（P4）。将垂体前叶细胞分散、培养，并在培养第4天（第0天 = 接种日）分别用10⁻⁷ M促性腺激素释放激素（GnRH）或IGF-I（10⁻¹¹、10⁻¹⁰、10⁻⁹、10⁻⁸或3×10⁻⁸ M）单独或联合进行刺激。血清E2和P4浓度表明动物处于发情周期的适当阶段。与FOL和LUT组动物相比，OVX组动物的平均血清LH浓度更高（p < 0.0004）。与FOL和LUT组动物相比，OVX组动物的平均血清IGF-I浓度更低（p < 0.05），而不同组动物的血清IGFBP无差异。OVX组培养物中基础LH分泌（对照）比FOL或LUT组培养物中的基础LH分泌更高（p < 0.04）。相对于对照，10⁻¹¹ M IGF-I可增加FOL、LUT和OVX组培养物中的LH分泌（p < 0.02），且FOL和OVX组的这种反应比LUT组培养物中的反应更大（p < 0.05）。仅10⁻¹¹ M IGF-I可增强LUT组培养物中的基础LH分泌。此外，10⁻¹⁰ M IGF-I可增加OVX组培养物中的LH分泌（p < 0.05），10⁻¹⁰和10⁻⁹ M IGF-I可刺激FOL组培养物中的LH分泌（p < 0.05），而10⁻⁸或3×10⁻⁸ M IGF-I对所有组的基础LH分泌均无影响（p > 0.05）。IGF-I处理未改变GnRH诱导的LH分泌。结果表明，体外IGF-I处理可增加基础LH分泌，生殖状态可调节LH对IGF-I的反应。
