Zhao S, Malmgren C H, Shanks R D, Sherwood O D
Department of Physiology, University of Illinois-Urbana-Champaign 61801, USA.
Endocrinology. 1995 May;136(5):1892-7. doi: 10.1210/endo.136.5.7720635.
Recent studies demonstrated that exogenous relaxin promoted drinking in nonpregnant rats. The purpose of this investigation was to determine the influence of endogenous relaxin on water consumption in pregnant rats. To that end, a monoclonal antibody specific for rat relaxin, designated MCA1, was used to passively neutralize endogenous relaxin throughout the second half of pregnancy in intact rats. Five milligrams of highly purified MCA1 were administrated iv to rats daily from days 12-22 of pregnancy. Controls received either a monoclonal antibody for fluorescein (monoclonal antibody control) or PBS (vehicle control). The amount of water consumed and both the total duration of water consumption and the total number of episodes when water was consumed were determined daily during both dark and light periods for all treatment groups. From days 13-22 of pregnancy, all three of these parameters of water consumption increased during the 10-h dark period (P < 0.01), but not during the 14-h light period. The mean daily water consumption in MCA1-treated rats was significantly less than that in controls (P < 0.05). Relaxin's effects on water consumption were limited to the 14-h light period (P < 0.01). No difference was found in daily water consumption between the MCA1-treated and control groups during the 10-h dark period. There was a tendency during the light period for both the total duration of water consumption (P = 0.06) and the total number of episodes when water was consumed (P = 0.13) to be less in MCA1-treated rats than in controls. Food consumption and body weight increased as pregnancy progressed, but no differences were found among the three treatment groups. We conclude that endogenous relaxin has effects on water consumption. It promotes water consumption during the daily light period in the second half of pregnancy in rats. Thus, relaxin may be a dipsogenic agent.
近期研究表明，外源性松弛素可促进未孕大鼠饮水。本研究的目的是确定内源性松弛素对孕鼠饮水的影响。为此，在完整大鼠妊娠后半期，使用一种对大鼠松弛素具有特异性的单克隆抗体（命名为MCA1）被动中和内源性松弛素。从妊娠第12天至第22天，每天给大鼠静脉注射5毫克高度纯化的MCA1。对照组分别接受荧光素单克隆抗体（单克隆抗体对照组）或磷酸盐缓冲液（溶剂对照组）。在明暗周期中，每天测定所有治疗组的饮水量、饮水总时长以及饮水次数。从妊娠第13天至第22天，在10小时黑暗期内，所有这三个饮水参数均增加（P<0.01），但在14小时光照期内未增加。MCA1处理组大鼠的日均饮水量显著低于对照组（P<0.05）。松弛素对饮水的影响仅限于14小时光照期（P<0.01）。在10小时黑暗期，MCA1处理组和对照组的日均饮水量无差异。在光照期，MCA1处理组大鼠的饮水总时长（P = 0.06）和饮水次数（P = 0.13）均有低于对照组的趋势。随着妊娠进展，食物摄入量和体重增加，但三个治疗组之间未发现差异。我们得出结论，内源性松弛素对饮水有影响。它促进大鼠妊娠后半期每日光照期的饮水。因此，松弛素可能是一种致渴剂。
