Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA.
Neuroscience. 2012 Dec 13;226:397-410. doi: 10.1016/j.neuroscience.2012.09.014. Epub 2012 Sep 16.
Anabolic androgenic steroids (AAS), synthetic testosterone derivatives that are used for ergogenic purposes, alter neurotransmission and behaviors mediated by GABA(A) receptors. Some of these effects may reflect direct and rapid action of these synthetic steroids at the receptor. The ability of other natural allosteric steroid modulators to alter GABA(A) receptor-mediated currents is dependent upon the phosphorylation state of the receptor complex. Here we show that phosphorylation of the GABA(A) receptor complex immunoprecipitated by β(2)/β(3) subunit-specific antibodies from the medial preoptic area (mPOA) of the mouse varies across the estrous cycle; with levels being significantly lower in estrus. Acute exposure to the AAS, 17α-methyltestosterone (17α-MeT), had no effect on the amplitude or kinetics of inhibitory postsynaptic currents in the mPOA of estrous mice when phosphorylation was low, but increased the amplitude of these currents from mice in diestrus, when it was high. Inclusion of the protein kinase C (PKC) inhibitor, calphostin, in the recording pipette eliminated the ability of 17α-MeT to enhance currents from diestrous animals, suggesting that PKC-receptor phosphorylation is critical for the allosteric modulation elicited by AAS during this phase. In addition, a single injection of 17α-MeT was found to impair an mPOA-mediated behavior (nest building) in diestrus, but not in estrus. PKC is known to target specific serine residues in the β(3) subunit of the GABA(A) receptor. Although phosphorylation of these β(3) serine residues showed a similar profile across the cycle, as did phosphoserine in mPOA lysates immunoprecipitated with β2/β3 antibody (lower in estrus than in diestrus or proestrus), the differences were not significant. These data suggest that the phosphorylation state of the receptor complex regulates both the ability of AAS to modulate receptor function in the mPOA and the expression of a simple mPOA-dependent behavior through a PKC-dependent mechanism that involves the β(3) subunit and other sites within the GABA(A) receptor complex.
合成代谢雄激素类固醇（AAS）是一种用于促进运动表现的人工合成睾酮衍生物，它可以改变 GABA(A) 受体介导的神经递质传递和行为。这些影响中的一些可能反映了这些合成类固醇在受体上的直接和快速作用。其他天然变构类固醇调节剂改变 GABA(A) 受体介导电流的能力取决于受体复合物的磷酸化状态。在这里，我们显示了从小鼠中脑前内侧区（mPOA）β(2)/β(3)亚基特异性抗体免疫沉淀的 GABA(A) 受体复合物的磷酸化在动情周期中发生变化；在动情期水平显著降低。在动情期小鼠低磷酸化时，急性暴露于 AAS 17α-甲基睾酮（17α-MeT）对 mPOA 抑制性突触后电流的幅度或动力学没有影响，但增加了高磷酸化时的去势小鼠的电流幅度。在记录电极中包含蛋白激酶 C（PKC）抑制剂钙泊酚消除了 17α-MeT 增强去势动物电流的能力，表明 PKC-受体磷酸化对于 AAS 在这个阶段引起的变构调节至关重要。此外，单次注射 17α-MeT 被发现会损害去势时 mPOA 介导的行为（筑巢），但不会在动情期损害。PKC 已知会靶向 GABA(A) 受体β(3)亚基的特定丝氨酸残基。尽管这些β(3)丝氨酸残基的磷酸化在整个周期中呈现出相似的模式，就像用β2/β3 抗体免疫沉淀的 mPOA 裂解物中的磷酸丝氨酸一样（动情期低于去势期或动情前期），但差异并不显著。这些数据表明，受体复合物的磷酸化状态调节 AAS 调节 mPOA 中受体功能的能力，以及通过涉及 GABA(A) 受体复合物的β(3)亚基和其他位点的 PKC 依赖性机制表达简单的 mPOA 依赖性行为。
