Faculty of Science, School of Psychology, The University of Sydney, Sydney, NSW, 2006, Australia.
Brain and Mind Centre, The University of Sydney, 94 Mallett Street, Camperdown, Sydney, NSW, 2050, Australia.
Psychopharmacology (Berl). 2022 Feb;239(2):429-442. doi: 10.1007/s00213-021-06014-3. Epub 2021 Nov 3.
Daily limited access to palatable food or drink at a fixed time is commonly used in rodent models of bingeing. Under these conditions, entrainment may modulate intake patterns. Oxytocin is involved in circadian patterns of intake and, when administered peripherally, reduces sucrose intake. However, oxytocin's effects on intake under limited-access conditions and its potential interaction with entrainment have not been explored.
This study examined the role of entrainment on intake patterns, oxytocin's effects on sucrose intakes and locomotor activity and whether oxytocin's effects were mediated by its actions at the oxytocin receptor.
Sated rats received daily 1-h access to 10% sucrose solution either at a fixed or varied time of day. Rats received intraperitoneal oxytocin (0 mg/kg, 0.3 mg/kg, 1 mg/kg, 3 mg/kg) prior to sucrose access, and spontaneous locomotor activity was assessed in an open-field test. Rats were then pre-treated with an oxytocin receptor antagonist, L368,899, prior to oxytocin before sucrose access.
Intake patterns did not differ between fixed- or varied-time presentations; rats consumed more sucrose solution in the middle as opposed to the early-dark phase. Oxytocin dose-dependently reduced sucrose intakes, but also reduced locomotor activity. There was some evidence of partial blockade of oxytocin-induced sucrose intake reductions by L368,899, but the results were unclear.
Time of day and oxytocin impact sucrose solution intake under daily limited access in rats and the sedative-like effects of oxytocin should be considered in future studies on oxytocin and food intake.
在暴食的啮齿动物模型中，每天限时摄入美味的食物或饮料是很常见的。在这些条件下，同步可能会调节摄入模式。催产素参与了摄入的昼夜节律模式，当外周给药时，它会减少蔗糖的摄入。然而，催产素在限时摄入条件下对摄入的影响及其与同步的潜在相互作用尚未得到探索。
本研究探讨了同步对摄入模式的作用、催产素对蔗糖摄入和运动活动的影响，以及催产素的作用是否是通过其在催产素受体上的作用介导的。
在固定或变化的时间给予大鼠每日 1 小时的 10%蔗糖溶液摄入。在蔗糖摄入前，大鼠接受腹腔内催产素（0 毫克/千克、0.3 毫克/千克、1 毫克/千克、3 毫克/千克），并在开放场测试中评估自发运动活动。然后，在给予催产素之前，大鼠用催产素受体拮抗剂 L368,899 进行预处理。
固定时间或变化时间呈现的摄入模式没有差异；大鼠在中-暗期比早-暗期消耗更多的蔗糖溶液。催产素剂量依赖性地减少蔗糖摄入，但也减少了运动活动。L368,899 对催产素诱导的蔗糖摄入减少有部分阻断作用，但结果不清楚。
时间和催产素都会影响大鼠在每日限时摄入蔗糖溶液时的摄入，在未来关于催产素和食物摄入的研究中，应该考虑到催产素的镇静作用。
