Sterin A B, Goldraij A, Gimeno M A, Gimeno A L
Cátedra de Fisiología, Facultad de Odontología, Universidad Nacional de Córdoba, Buenos Aires, Argentina.
Prostaglandins Leukot Med. 1987 Sep;29(1):33-47. doi: 10.1016/0262-1746(87)90095-3.
The influences of a period of 15 days of restricted diet (50% of the normal food intake) in rats sacrificed at different stages of the sex cycle (proestrus, estrus, metestrus and diestrus), were explored on: (1) the magnitude of uterine spontaneous phasic contractions (isometric developed tension = IDT); (2) the release of prostaglandins (PGs) F2 alpha and E2; from the uterus and (3) the myometrial inotropic responses evoked by methoxamine and indomethacin. At estrus and at proestrus, preparations from restricted diet rats exhibited greater initial (post-isolation) IDT and better contractile constancy during 60 min than did uteri from normal fed rats. This enhanced contractile constancy, but not that of preparations from control fed rats, was prevented by incubation "in vitro" with indomethacin (10(-6) M). At metestrus and at diestrus, uteri from normal fed rats presented higher initial levels of IDT and even more sustained contractile constancy than at estrus or at proestrus. Moreover, contractile profiles remained unaltered following the dietary restriction and the presence of indomethacin evoked similar negative inotropic actions in both experimental groups (fed and underfed). Dose-response curves for methoxamine documented its positive, but different, inotropic actions in the two groups and at the four periods of the estrous cycle. Indeed, in the underfed group at estrus and at proestrus, dose-response curves for methoxamine were shifted to the left of those in fed controls, a situation prevented by indomethacin (10(-6) M); whereas at metestrus and at diestrus, no differences in the inotropic reactivity towards methoxamine between the two experimental groups, were detected. On the other hand, indomethacin shifted to the right dose-response curves for the agonist, both in preparations from normal fed and from restricted diet rats. The generation and release of PGF2 alpha and of PGE2 were explored under normal and restricted diet conditions, both at estrus and at diestrus. Following the dietary restriction, the output of PGE2 from estrous uteri was augmented in comparison to controls, whilst the release of PGF2 alpha was not affected. At diestrus, dietary restriction failed to alter the uterine output of either one of these PGs. Results suggest that a greater generation and release of PGE2, following underfeeding, appears to subserve the increased spontaneous motility and the greater sensitivity of the rat uterus for adrenoreceptor agonists.
研究了在不同性周期阶段（动情前期、动情期、动情后期和动情间期）处死的大鼠，进行15天限食（正常食物摄入量的50%）对以下方面的影响：（1）子宫自发性阶段性收缩的幅度（等长收缩张力=IDT）；（2）前列腺素（PGs）F2α和E2从子宫中的释放；以及（3）甲氧明和吲哚美辛引起的子宫肌层变力反应。在动情期和动情前期，限食大鼠的组织在分离后最初表现出比正常喂食大鼠的子宫更大的IDT，并且在60分钟内收缩稳定性更好。这种增强的收缩稳定性，而非对照喂食大鼠组织的收缩稳定性，在“体外”与吲哚美辛（10⁻⁶M）孵育后被阻止。在动情后期和动情间期，正常喂食大鼠的子宫呈现出比动情期或动情前期更高的初始IDT水平，甚至收缩稳定性更持久。此外，饮食限制后收缩曲线保持不变，并且在两个实验组（喂食和未喂食）中，吲哚美辛的存在引起了类似的负性变力作用。甲氧明的剂量-反应曲线记录了其在两组以及发情周期的四个时期中不同的正性变力作用。实际上，在未喂食组的动情期和动情前期，甲氧明的剂量-反应曲线相较于喂食对照组向左移动，这种情况被吲哚美辛（10⁻⁶M）阻止；而在动情后期和动情间期，未检测到两个实验组对甲氧明的变力反应性存在差异。另一方面，吲哚美辛使正常喂食和限食大鼠组织中激动剂的剂量-反应曲线均向右移动。在正常和限食条件下，分别在动情期和动情间期研究了PGF2α和PGE2的生成和释放。饮食限制后，与对照组相比，动情期子宫中PGE2的输出增加，而PGF2α的释放未受影响。在动情间期，饮食限制未能改变这两种PGs中任何一种的子宫输出。结果表明，喂食不足后PGE2生成和释放增加，似乎有助于大鼠子宫自发运动增加以及对肾上腺素能受体激动剂的敏感性增强。
