Sanghani M P, Scarpace P J
Geriatric Research, Education and Clinical Center, VA Medical Center, Gainesville, Florida.
J Gerontol. 1994 Mar;49(2):B60-4. doi: 10.1093/geronj/49.2.b60.
This study was designed to determine whether functional beta 3-adrenergic receptors exist in the rat liver and whether there are alterations in the beta 3-adrenergic response with age in a manner similar to that which occurs for beta 2-adrenergic receptors. The beta 3 stimulation of adenylyl cyclase activity was assessed using the novel beta 3-specific agonist, CGP-12177A. Adenylyl cyclase activation by CGP-12177A was seen only in the adults. Isoproterenol-stimulated adenylyl cyclase activity was high in the neonates, declined by 45% in the adults, and was high again in the senescent rats. ICI 118551, a beta 2-selective antagonist, attenuated the isoproterenol-stimulated activity by two-thirds but had no effect on the CGP-12177A-stimulated activity. These data demonstrated the presence of the beta 3-adrenergic receptor in the rat liver, although only at the adult stage of development. In addition, these data confirm earlier findings that beta 2-adrenergic activation of adenylyl cyclase is biphasic with age and indicate that the emergence of the beta 3-stimulated activity coincides with the attenuation of beta 2-stimulated activity.
本研究旨在确定大鼠肝脏中是否存在功能性β3 - 肾上腺素能受体，以及β3 - 肾上腺素能反应是否会随着年龄增长而发生变化，其变化方式是否类似于β2 - 肾上腺素能受体的变化。使用新型β3特异性激动剂CGP - 12177A评估腺苷酸环化酶活性的β3刺激情况。仅在成年大鼠中观察到CGP - 12177A激活腺苷酸环化酶。异丙肾上腺素刺激的腺苷酸环化酶活性在新生大鼠中较高，在成年大鼠中下降了45%，而在衰老大鼠中又再次升高。β2选择性拮抗剂ICI 118551使异丙肾上腺素刺激的活性减弱了三分之二，但对CGP - 12177A刺激的活性没有影响。这些数据证明了大鼠肝脏中存在β3 - 肾上腺素能受体，尽管仅在发育的成年阶段存在。此外，这些数据证实了早期的发现，即腺苷酸环化酶的β2 - 肾上腺素能激活随年龄呈双相变化，并表明β3刺激活性的出现与β2刺激活性的减弱同时发生。
