Lowenstein P R, Vacas M I, Cardinali D P
Neuropharmacology. 1982 Mar;21(3):243-8. doi: 10.1016/0028-3908(82)90194-0.
The intraperitoneal injection of the methylxanthine derivative pentoxifylline (3,7-dimethyl-1-(5-oxo-hexyl)-xanthine] brought about, 3 hr later, a significant depression of alpha- and beta-adrenoceptor sites in the cerebral cortex, and of beta-adrenoceptor sites in medial basal hypothalamus and pineal gland, (assessed from the specific binding of radioactive dihydroergocryptine and dihydroalprenolol respectively). The changes in the density of binding sites were not accompanied by significant modifications of the Kd's. Sympathetic denervation of the pineal gland by superior cervical ganglionectomy (SCGx) abolished the changes of beta-adrenoceptor number in the pineal caused by pentoxifylline. The increase of alpha-adrenoceptor sites in the hypothalamus brought about by ganglionectomy was not affected by injection of pentoxifylline. Pentoxifylline did not compete in vitro for radioligand binding to brain membranes. These results suggest that methylxanthines depress brain adrenoceptor sites acutely, probably by down-regulation of receptors following the increase in catecholamine release caused by injection of the drug.
腹腔注射甲基黄嘌呤衍生物己酮可可碱（3,7 - 二甲基 - 1 -（5 - 氧代己基）黄嘌呤）3小时后，大脑皮层中的α和β肾上腺素能受体位点以及内侧基底下丘脑和松果体中的β肾上腺素能受体位点出现显著减少（分别通过放射性二氢麦角隐亭和二氢心得舒的特异性结合进行评估）。结合位点密度的变化并未伴随解离常数（Kd）的显著改变。通过颈上神经节切除术（SCGx）对松果体进行交感神经去支配消除了己酮可可碱引起的松果体中β肾上腺素能受体数量的变化。神经节切除术导致的下丘脑α肾上腺素能受体位点增加不受己酮可可碱注射的影响。己酮可可碱在体外不与放射性配体竞争与脑膜的结合。这些结果表明，甲基黄嘌呤可能通过药物注射引起的儿茶酚胺释放增加后受体下调，从而急性抑制脑内肾上腺素能受体位点。
