内源性精氨酸加压素在昼光期大鼠紧张性体温调节中的作用

Role of endogenous arginine vasopressin in tonic thermoregulatory processes in rats during the light phase

目的:探讨内源性精氨酸加压素(AVP)在昼光期大鼠紧张性体温调节中的作用及其机制。方法:使用成年雄性SD大鼠,在22℃环境温度下,明暗时间各12 h,同步无线遥测体核温度(Tc)和棕色脂肪(BAT)温度。上午10:00给大鼠腹腔注射AVP(10μg/kg)或精氨酸加压素V1a(AVP V1a)受体阻断剂(30μg/kg)。用酶联免疫吸附测定法,分别检测昼光期和暗光期大鼠血浆中AVP浓度。给AVP 60 min后测定血清中甘油三酯、游离脂肪酸和甘油浓度变化。给予AVP后间隔10 min记录大鼠的理毛活动。结果:(1)在昼光期中AVP V1a受体阻断剂能够升高Tc和BAT温度。(2)在昼光中Tc和BAT温度处于低温期时,血浆中AVP水平则明显提高。(3)腹腔注射AVP引起Tc快速降低时,伴有BAT温度明显降低和大鼠的理毛行为明显增加。(4)AVP可以降低血清游离脂肪酸与甘油浓度,提高血清甘油三酯的浓度。结论:(1)内源性AVP通过AVP V1a受体参与昼光期大鼠紧张性体温调节过程,因为在昼光期中不仅血浆AVP浓度明显高于暗光期,而且AVP V1a受体阻断剂也能明显升高Tc和BAT温度。(2)AVP能降低BAT温度、血中游离脂肪酸和甘油浓度,提高理毛活动,证明AVP引起低温的机制可能与抑制脂肪分解、降低BAT产热和提高散热反应有关。

AIM： To determine the role of endogenous arginine vasopressin（AVP） in tonic thermoregulatory processes in rats during the light phase.METHODS： The core temperature（Tc） and temperature in brown adipose tissue（BAT） were simultaneously measured by telemetry in adult male Sprague-Dawley rats at an ambient temperature of 22 °C during a 12-h light/12-h dark photoperiod.At 10：00,the rats were intraperitoneally injected with V1a vasopressin receptor antagonist（30 μg/kg） or AVP（10 μg/kg）.Plasma AVP concentration was measured by an enzyme-linked immunosorbant assay during the light phase and dark phase.Serum triglyceride,free fatty acid and glycerol were measured 60 min after AVP treatment.Grooming activities were also observed at 10-min intervals after AVP treatment.RESULTS： V1a vasopressin receptor antagonist elevated the Tc and BAT temperature during the light period.The plasma AVP level was significantly elevated when Tc and BAT temperature decreased during the light phase.Intraperitoneal injection of AVP elicited rapid drop in Tc concomitant with a marked decrease in BAT temperature,and also increased grooming behavior in the rats.Intraperitoneal injection of AVP produced a decrease in serum free fatty acid and glycerol,and an increase in serum triglyceride.CONCLUSION： Endogenous AVP,acting through V1a vasopressin receptor,is involved in tonic thermoregulatory processes in male rats during the light phase because plasma AVP concentration is higher during light period than that during dark period,and V1a vasopressin receptor antagonist elevates the Tc and BAT temperature.AVP decreases BAT temperature,serum free fatty acid and glycerol,and increases grooming behavior,suggesting that the mechanism of AVP-induced hypothermia is involved in suppression of lipolysis,decrease in BAT thermogenesis and increase in heat loss.