Based on studies using mutations of the µ-opioid receptor (MOR), phosphorylation of multiple sites on the C-terminus has been recognized as a critical step underlying acute desensitization and the development of cellular tolerance. The aim of this study is to explore which kinases mediate desensitization of MOR in brain slices from drug-naïve and morphine-treated animals. Whole-cell recordings from locus coeruleus neurons were made, and the agonist-induced increase in potassium conductance was measured. In slices from naïve animals, pharmacological inhibition of G-protein receptor kinase (GRK2/3) with compound 101 blocked acute desensitization. Following chronic treatment with morphine, compound 101 was less effective at blocking acute desensitization. Compound 101 blocked receptor internalization in tissue from both naïve and morphine-treated animals, suggesting that GRK2/3 remained active. Kinase inhibitors aimed at blocking protein kinase C and c-Jun N-terminal kinase had no effect on desensitization in tissue taken from naïve animals. However, in slices taken from morphine-treated animals, the combination of these blockers along with compound 101 was required to block acute desensitization. Acute desensitization of the potassium conductance induced by the somatostatin receptor was also blocked by compound 101 in slices from naïve but not morphine-treated animals. As was observed with MOR, it was necessary to use the combination of kinase inhibitors to block desensitization of the somatostatin receptor in slices from morphine-treated animals. The results show that chronic treatment with morphine results in a surprising and heterologous adaptation in kinase-dependent desensitization.

中文翻译：

---

吗啡的慢性治疗会破坏 GPCR 的急性激酶依赖性脱敏。

基于使用µ突变的研究-阿片受体 (MOR)，C 端多个位点的磷酸化已被认为是急性脱敏和细胞耐受性发展的关键步骤。本研究的目的是探索哪些激酶介导了未经药物治疗和吗啡治疗动物脑切片中 MOR 的脱敏。对蓝斑神经元的全细胞记录进行了记录，并测量了激动剂诱导的钾电导增加。在来自幼稚动物的切片中，用化合物 101 对 G 蛋白受体激酶 (GRK2/3) 的药理学抑制阻止了急性脱敏。在用吗啡长期治疗后，化合物 101 在阻断急性脱敏方面效果较差。化合物 101 阻断了未经处理和接受吗啡处理的动物组织中的受体内化作用，表明 GRK2/3 保持活跃。旨在阻断蛋白激酶 C 和 c-Jun N 末端激酶的激酶抑制剂对取自幼稚动物的组织的脱敏没有影响。然而，在取自吗啡治疗动物的切片中，需要这些阻滞剂与化合物 101 的组合来阻止急性脱敏。生长抑素受体诱导的钾电导的急性脱敏也被化合物 101 在来自未接受过吗啡治疗的动物的切片中阻断。正如在 MOR 中观察到的那样，有必要使用激酶抑制剂的组合来阻止吗啡治疗动物切片中生长抑素受体的脱敏。结果表明，吗啡的长期治疗导致激酶依赖性脱敏的惊人和异源适应。旨在阻断蛋白激酶 C 和 c-Jun N 末端激酶的激酶抑制剂对取自幼稚动物的组织的脱敏没有影响。然而，在取自吗啡治疗动物的切片中，需要这些阻滞剂与化合物 101 的组合来阻止急性脱敏。生长抑素受体诱导的钾电导的急性脱敏也被化合物 101 在来自未接受过吗啡治疗的动物的切片中阻断。正如在 MOR 中观察到的那样，有必要使用激酶抑制剂的组合来阻止吗啡治疗动物切片中生长抑素受体的脱敏。结果表明，吗啡的长期治疗导致激酶依赖性脱敏的惊人和异源适应。旨在阻断蛋白激酶 C 和 c-Jun N 末端激酶的激酶抑制剂对取自幼稚动物的组织的脱敏没有影响。然而，在取自吗啡治疗动物的切片中，需要这些阻滞剂与化合物 101 的组合来阻止急性脱敏。生长抑素受体诱导的钾电导的急性脱敏也被化合物 101 在来自未接受过吗啡治疗的动物的切片中阻断。正如在 MOR 中观察到的那样，有必要使用激酶抑制剂的组合来阻止吗啡治疗动物切片中生长抑素受体的脱敏。结果表明，吗啡的长期治疗导致激酶依赖性脱敏的惊人和异源适应。