Bauer M, Parvizi N
Department of Endocrinology, Institut für Tierzucht und Tierverhalten, Neustadt/Rbge, Germany.
J Endocrinol. 1996 Apr;149(1):125-33. doi: 10.1677/joe.0.1490125.
The ontogeny of GH and IGF-I secretion was investigated in the fetal pig. Pulse studies were performed to describe the pattern of GH release. Twenty-four-hour profiles were recorded to examine possible diurnal variations in these hormones. (I) PULSE STUDIES: Blood samples were obtained at 15-min intervals for 2-h periods from 24 male and 20 female fetuses at various gestational ages (fetal day 89-113; term 113 +/- 1 S.D.). Fetuses revealed a pulsatile GH release. The GH pulse frequency did not vary with gestational age in either sex (0.95 +/- 0.19 pulses/h). In males the GH pulse amplitude decreased with increasing fetal age (r = -0.41; P < 0.02). In female fetuses no significant correlation could be calculated. Mean GH concentrations fell significantly in male fetuses 3 to 4 days before delivery (P < 0.05) and the same tendency was observed in females (P < 0.06). Between fetal days 94 and 98 GH pulse amplitude and GH and IGF-I concentrations were higher in males than in females (P < 0.01, P < 0.001 and P < 0.02 respectively). Fetal IGF-I secretion showed no ontogenetic changes in both sexes. However, maternal IGF-I concentrations increased with progressing gestation (r = 0.46; P < 0.001). (II) 24-H PROFILES: Eight male and four female late-gestational fetuses (fetal days 104-108) were studied. Blood samples were taken at 30-min intervals over 24 h. Dams and fetuses showed an episodic GH secretion over the 24-h period but no diurnal rhythm was observed. Whereas maternal IGF-I secretion was constant, fetal IGF-I release was characterized by marked fluctuations over the 24 h. In half of the fetuses (n = 6) the fluctuations appeared at regular intervals. Again no diurnal rhythm existed. These data demonstrated that: (1) porcine fetal GH secretion is pulsatile and decreases shortly before birth; (2) a sex difference in GH and IGF-I concentrations exists between fetal days 94 and 98, suggesting that IGF-I is at least partially under the control of GH before birth; (3) fetal GH and IGF-I secretion is episodic over 24 h, but does not vary diurnally; and (4) fetal and maternal GH and IGF-I secretion are regulated independently.
研究了胎猪生长激素（GH）和胰岛素样生长因子-I（IGF-I）分泌的个体发生情况。进行脉冲研究以描述GH释放模式。记录24小时曲线以检查这些激素可能的昼夜变化。（I）脉冲研究：在不同胎龄（胎龄89 - 113天；足月为113±1标准差）的24只雄性和20只雌性胎儿中，每隔15分钟采集一次血样，共采集2小时。胎儿呈现出脉冲式GH释放。GH脉冲频率在两性中均不随胎龄变化（0.95±0.19次/小时）。在雄性中，GH脉冲幅度随胎龄增加而降低（r = -0.41；P < 0.02）。在雌性胎儿中，未计算出显著相关性。雄性胎儿在分娩前3至4天平均GH浓度显著下降（P < 0.05），雌性中也观察到相同趋势（P < 0.06）。在胎龄94至98天之间，雄性胎儿的GH脉冲幅度以及GH和IGF-I浓度均高于雌性（分别为P < 0.01、P < 0.001和P < 0.02）。两性胎儿的IGF-I分泌均未显示个体发生变化。然而，母体IGF-I浓度随妊娠进展而增加（r = 0.46；P < 0.001）。（II）24小时曲线：研究了8只雄性和4只雌性妊娠晚期胎儿（胎龄104 - 108天）。每隔30分钟采集一次血样，共采集24小时。母羊和胎儿在24小时期间均呈现出间歇性GH分泌，但未观察到昼夜节律。母体IGF-I分泌恒定，而胎儿IGF-I释放在24小时内有明显波动。在一半的胎儿（n = 6）中，波动有规律地出现。同样不存在昼夜节律。这些数据表明：（1）猪胎儿GH分泌是脉冲式的，且在出生前不久下降；（2）在胎龄94至98天之间，GH和IGF-I浓度存在性别差异，表明出生前IGF-I至少部分受GH控制；（3）胎儿GH和IGF-I分泌在24小时内是间歇性的，但无昼夜变化；（4）胎儿和母体的GH和IGF-I分泌是独立调节的。
