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I Akiba

Publications and source records attributed to I Akiba.

21 records · Page 2Linked to original sources
PubMed1982

[Plasma corticosterone concentration in morphine-dependent rats].

The effects of morphine on plasma corticosterone concentration in rats were studied using the drug-admixed food method. Morphine was mixed with the powder form of rat food in concentrations of 0.5 mg/g, 1 mg/g, and 2 mg/g of food. Plasma corticosterone concentration in rats treated with morphine-admixed food increased significantly, and the increment depended on the morphine concentration of drug-admixed food. The time course change of plasma corticosterone concentration in rats treated with morphine-admixed food (1 mg/g food) for 1 week was similar to that of non-treated rats without the concentration at 9:00. The plasma corticosterone concentration of morphine-treated rats at 9:00 was significantly increased in comparison with that of non-treated rats. Furthermore, the plasma corticosterone concentration after withdrawal in morphine-treated rats increased with time, and a significant increment in corticosterone was observed at 24 hr after the withdrawal. Naloxone, injected subcutaneously into morphine-dependent rats, significantly increased plasma corticosterone concentration. Increment of plasma corticosterone concentration in rats treated with morphine-admixed food for 3 or 4 weeks was significantly different from the non-treated group. The increment of plasma corticosterone concentration after the withdrawal was in a morphine treatment period-related manner. By these results, we suggest that tolerance to the increment action in plasma corticosterone concentration of morphine does not develop for at least 4 weeks using the drug-admixed food method, and the drug-admixed food method could induce morphine dependence without disturbance of the circadian rhythm in plasma corticosterone.

Animals↗
PubMedDate not supplied

Molecular distinction between muscarinic acetylcholine receptor subtypes.

The muscarinic acetylcholine receptor (mAChR) mediates various cellular responses, including inhibition of adenylate cyclase, breakdown of phosphoinositides and modulation of potassium channels, through the action of guanine nucleotide-binding regulatory proteins. Pharmacologically distinguishable forms of the mAChR occur in different tissues and have provisionally been classified into M1 (I), M2 cardiac (II) and M2 glandular (III) subtypes on the basis of their difference in apparent affinity for antagonists. In an attempt to elucidate the molecular basis of the functional heterogeneity of the mAChR, we have cloned and sequenced DNAs complementary to porcine cerebral and cardiac messenger RNAs encoding mAChRs and have thereby deduced the primary structures of the receptor proteins. We report here that the messenger RNA generated by transcription of the cardiac complementary DNA directs the formation of a functional mAChR in Xenopus oocytes and that this mAChR differs from the mAChR formed by expression of the cerebral cDNA both in acetylcholine (ACh)-induced response and in antagonist binding properties. Our results provide evidence indicating that the mAChR encoded by the cerebral cDNA (designated as mAChR I) and the mAChR encoded by the cardiac cDNA (mAChR II) are of the M1 (I) and the M2 cardiac (II) subtype, respectively.

Acetylcholine↗