Janowski B A, Wehrenberg W B
Department of Health Science, University of Wisconsin-Milwaukee.
Life Sci. 1992;50(13):951-8. doi: 10.1016/0024-3205(92)90173-m.
Pulsatile GH secretion decreases during food-deprivation in the rat. It has been hypothesized that this decrease is due to elevated hypothalamic somatostatin secretion. This is based on the observation that GH increases in food-deprived rats following removal of endogenous somatostatin using passive immunization techniques. Cognizant of the important stimulatory effects of growth hormone-releasing hormone (GHRH) on GH secretion, we sought to determine if this neuropeptide plays any role in mediating GH secretion in food-deprived rats. Male rats were prepared with indwelling venous catheters using sodium pentobarbital anesthesia seven days prior to experimentation. Animals were food-deprived for 72 h, after which control blood samples were drawn from -60 to 0 min. One group was then treated with normal rabbit serum (NRS), while a second group was treated with GHRH antiserum (GHRHab). At 55 min all animals received somatostatin antiserum (SSab). No animal exhibited any spontaneous GH peak during the one hour control period or in the subsequent one hour period following the administration of GHRHab or NRS. Absence of GH pulsatility during food-deprivation, coupled with no decrease in GH levels in food-deprived rats treated with GHRHab suggest that diminished GHRH pulsatility is likely during food-deprivation. Subsequent treatment of these animals with SSab resulted in an identical 2.5 fold increase in GH concentrations. This result suggests that GHRH is not involved in the GH rebound following somatostatin withdrawal in food-deprived rats.
在大鼠禁食期间，脉冲式生长激素（GH）分泌减少。据推测，这种减少是由于下丘脑生长抑素分泌增加所致。这是基于以下观察结果：使用被动免疫技术去除内源性生长抑素后，禁食大鼠的GH水平会升高。鉴于生长激素释放激素（GHRH）对GH分泌具有重要的刺激作用，我们试图确定这种神经肽在介导禁食大鼠的GH分泌中是否发挥任何作用。在实验前七天，使用戊巴比妥钠麻醉，为雄性大鼠植入留置静脉导管。动物禁食72小时，之后在-60至0分钟采集对照血样。然后一组用正常兔血清（NRS）处理，而另一组用GHRH抗血清（GHRHab）处理。在55分钟时，所有动物均接受生长抑素抗血清（SSab）。在一小时的对照期内或在给予GHRHab或NRS后的后续一小时内，没有动物出现任何自发的GH峰值。禁食期间GH缺乏脉冲性，以及用GHRHab处理的禁食大鼠的GH水平没有降低，这表明禁食期间GHRH的脉冲性可能降低。随后用SSab处理这些动物，导致GH浓度同样增加了2.5倍。这一结果表明，在禁食大鼠中，GHRH不参与生长抑素撤除后的GH反跳。
