Vaughan G M, Reiter R J
Endocrinology. 1987 Apr;120(4):1682-4. doi: 10.1210/endo-120-4-1682.
Failure of isoproterenol (ISO) injections to raise pineal melatonin content has generated doubt about beta-adrenergic control of the melatonin rhythm in Syrian hamsters. However, the effect of ISO injected at night after light-induced reduction of pineal melatonin has not been reported. In this study, light exposure began at 6 1/4 h into one (normally 10-h) dark phase. The hamsters were injected with either ISO (1 mg/kg) or vehicle 15 min later when pineal melatonin content was low. Light exposure continued. Two h after ISO but not vehicle injection, pineal melatonin content rose more than six-fold. In other animals injected at the end of the usual light phase then kept in light for 2 h, pineal melatonin was equally low after ISO or vehicle injection. The Syrian hamster pineal gland can respond in vivo to a beta-adrenergic agonist injected at the physiologically relevant time of the normal nocturnal melatonin surge. This finding, taken together with the previously reported inhibition of the endogenous nocturnal melatonin surge with a beta-blocking drug, suggests that a beta-adrenergic mechanism controls the hamster pineal melatonin rhythm.
注射异丙肾上腺素（ISO）未能提高叙利亚仓鼠松果体褪黑素含量，这引发了人们对β-肾上腺素能对叙利亚仓鼠褪黑素节律控制的质疑。然而，在光诱导松果体褪黑素减少后于夜间注射ISO的效果尚未见报道。在本研究中，光照在一个（通常为10小时）黑暗期开始后的6.25小时进行。当松果体褪黑素含量较低时，15分钟后给仓鼠注射ISO（1毫克/千克）或赋形剂。光照持续进行。注射ISO而非赋形剂2小时后，松果体褪黑素含量增加了六倍多。在通常光照期结束时注射然后再光照2小时的其他动物中，注射ISO或赋形剂后松果体褪黑素同样较低。叙利亚仓鼠松果体在正常夜间褪黑素分泌高峰的生理相关时间注射β-肾上腺素能激动剂后可在体内产生反应。这一发现，与先前报道的用β-阻断药物抑制内源性夜间褪黑素分泌高峰一起，表明β-肾上腺素能机制控制仓鼠松果体褪黑素节律。
