Polish journal of pharmacology and pharmacy最新文献

The circadian changes in elimination and absorption of amitriptyline after its intravenous and intragastric administration in rats were investigated. The values of such parameters as: AUC, MRT, t1/2, Cl, Vd, k(a) for amitriptyline change in the circadian rhythm. The fastest elimination of amitriptyline was observed in the dark phase (the acrophases for clearance were ca. 11 p.m. for iv administration and ca. 10 p.m. for po administration). The maximal value of clearance corresponds to the minimal values of MRT and t1/2. The acrophase for the constant absorption rate (po) falls at 7 p.m. Cyclic changes were not observed as far as the bioavailability is concerned.

The effects of levoprotiline (LEV), a (-)-enantiomer of oxaprotiline (OXA) and a clinically effective antidepressant, on the binding parameters of hippocampal 5-HT1A and cortical 5-HT2 receptors of rats were compared with those of (+)-enantiomer of OXA ((+)-OXA), imipramine and mianserin. Both LEV and (+)-OXA displayed in vitro some affinity for 5-HT1A receptors labelled with [3H]-8-OH-DPAT, and for 5-HT2 receptors labelled with [3H]-ketanserin. Repeated administration of LEV, for 14 days led to a marked increase in the number of 5-HT1A binding sites in the rat hippocampus, with no change in the KD values. (+)-OXA, imipramine and mianserin produced similar effects on 5-HT1A binding parameters. The number of 5-HT2 receptors was increased after two weeks of LEV administration, not altered after (+)-OXA, and decreased after imipramine or mianserin. The number of [3H]-ketanserin binding sites was decreased after four weeks of (+)-OXA administration, but not altered after LEV. The specific binding of [3H]-ketanserin in the rat cerebral cortex was decreased after repeated treatment with LEV and (+)-OXA (ex vivo). In competition studies the affinity of serotonin for [3H]-ketanserin binding sites was decreased in LEV- and increased in (+)-OXA-treated rats. The results suggest that LEV similarly to other antidepressants increases the number of 5-HT1A receptors, however without common alteration in 5-HT2 receptor number and function.

The present paper reports on the synthesis and preliminary pharmacological properties of N-[beta-hydroxy-gamma-(N-phenylpiperazinepropyl)]-2- pyrrolidinone (MG-1). MG-1 was obtained by aminolysis of 1-(beta, gamma-epoxypropyl)-2-pyrrolidinone and N-phenylpiperazine. Its structure was established by elemental and spectral analyses (IR, UV, MS, 1H, 13C, 2D H-H and 2D C-H NMR). The antiarrhythmic activity of MG-1 was investigated on mice, rats and guinea pigs, using several models of arrhythmia. MG-1 attenuated or prevented the adrenaline- and barium chloride-induced arrhythmia. MG-1 demonstrated potent local anesthetic properties and depressed the depolarization phase of the action potential of cardiac cells. These results indicate that MG-1 possesses antiarrhythmic activity.

The present review primarily summarizes the cellular and molecular biology of MEL synthesis by the vertebrate retina, and the nature of MEL signal generated in this tissue. Additionally, the current status of retinal MEL receptors as well as physiological roles of this indoleamine within the eye are discussed.

A few derivatives of natural, bicyclic monoterpenes, which are propranolol analogs, were synthetized. Those compounds were studied pharmacologically in order to determine their toxicity, antiarrhythmic activity in selected experimental models of arrhythmia, the local anesthetic effect and influence on the cardiovascular system. The tested compounds showed a less potent or similar toxicity towards reference drugs, were devoid of an antiarrhythmic activity in the model of barium arrhythmia, yet some of them (compounds 9 and 12) increased the arrhythmogenic dose of strophanthin. All the compounds studied had a local anesthetic effect stronger than lidocaine in infiltration anesthesia, and compound 8--also in surface anesthesia.

The metabolism of phenacetin in vivo and in vitro at different periods of day was investigated in rats. In rats maintained on standard LD conditions the disappearance rate of phenacetin from blood and activity of phenacetin O-deethylase in liver were the highest in the morning and the lowest in the evening. Continuous illumination, adrenalectomy, phenobarbital or proadifen abolished this difference. It is postulated that these circadian changes of microsomal metabolism of phenacetin in rats liver are not fully responsible for the rhythmical changes in the antipyretic action of this drug that was observed previously. The mechanisms of this phenomenon are discussed.

Circadian changes in cytochrome P-450 and cytochrome b5 content and activity of NADPH-cytochrome P-450 and NADH-cytochrome b5 reductases have been studied in rat liver microsomes in season autumn. The obtained results indicate, that cytochrome P-450 in 6-month-old animals shows 12 h rhythm, but in older ones 24 h rhythm. NADPH-cytochrome P-450 reductase activity shows 24 h rhythm in oldest animals only. Cytochrome b5 and its reductase has 24 h rhythm in all examined groups of rats.

The in vivo effects of GABA-ergic drugs on the activity of serotonin N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT), two enzymes involved in melatonin biosynthesis, were investigated in light-exposed chicken retina. The ip administration of muscimol and baclofen (direct agonists of GABA-A and GABA-B receptors, respectively), aminooxyacetic acid (an inhibitor of GABA transaminase), and nipecotic acid (an inhibitor of GABA reuptake), significantly increased the retinal NAT activity by 50-100%. Similar rises in NAT activity were observed following intraocular treatment of ether-anesthetized chickens with muscimol, baclofen and GABA. In contrast to NAT, there was no effect of the tested drugs on the retinal HIOMT activity. Aminophylline (a phosphodiesterase inhibitor) markedly elevated the retinal NAT activity, and a combined treatment with the GABA-ergic drugs and aminophylline resulted in additive effects. The actions of both muscimol and baclofen were antagonized by picrotoxin and bicuculline (two GABA-A receptor blockers), whereas the effect of baclofen was not changed by a selective GABA-B receptor blocker, CGP 35,348. Melatonin given ip significantly raised NAT activity, and its combination with muscimol further stimulated the enzyme. Picrotoxin and bicuculline given to chickens during the dark phase of 12 h light--12 h dark illumination cycle significantly suppressed the nocturnal NAT activity in retina. Neither GABA nor muscimol and baclofen significantly affected basal and forskolin (1 microM)-stimulated adenylate cyclase activity in vitro in light-exposed chicken retina. It is concluded that a GABA signal (acting through type A of GABA receptors) plays an important role in a complex mechanism regulating the rhythmic melatonin biosynthesis in vertebrate retina.

The effect of a steric hindrance around the protonation center of the model 4-substituted 1-(3-chlorophenyl)-piperazines 1-9 and 11-14 on their affinity for 5-HT1A and 5-HT2 receptor sites was investigated. Additional evidence for hydrophobic interactions between the N-4 hydrocarbon substituents and 5-HT1A receptors has been presented. However, the hydrophobic forces play a minor role in stabilization of the bioactive complex with 5-HT2 receptors. It has also been found that even bulky substituents around the protonation center of 1-aryl-piperazines are well tolerated at both 5-HT1A and 5-HT2 sites.

Our studies showed that the nifedipine in daily doses of 30 mg/kg given to rabbits treated with a diet containing 1% cholesterol for 6 months, decreased cholesterol content in aorta homogenates, urine excretion of desmosines and prolonged partial thromboplastin time, while it did not alter serum lipids. These results may have some value for understanding of the antiatherogenic mechanism of nifedipine.