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Classic serotonergic hallucinogens(also known as psychedelics)are powerful psychoactive substances that can induce profound alterations of human consciousness,emotion,and cognition. It is generally believed that the main target of psychedelics for their hallucinogenic effect is 5-hydroxytryptamine 2A receptor(5-HT
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OBJECTIVE To explore the mechanism of Gαiand Gβγsubunits on dexmedetomidine (DMED)-induced sedation.METHODS Kunming mice were randomly placed into three groups(DMED group, DMED+dbcAMP/rolipram/gallein/M119 group, dbcAMP/rolipram/gallein/M119 group) to explore the regulation of dbcAMP/rolipram/gallein/M119 on DMED-induced sedation by establishing loss of righting reflex (LORR) model. DbcAMP/rolipram was intracerebroventricular injected and gallein/M119 was intraperitoneal injected 15 min before DMED intravenous injection. In CHO-α2A-AR cells, after administration of DMED/gallein/M119, the regulation on the cAMP accumulation stimulated by Forskolin (FSK) was detected, so was the intracellular calcium ion concentration ([Ca2+]i. The levels of pERK/pCREB were detected by Western Blot to explore the key signal molecules involved in DMED-induced sedation. RESULTS The ED50of DMED-induced LORR (200.0 nmol·kg-1) was increased to 375.0 or 433.3 nmol·kg-1by pre-treatment with cAMP analog dbcAMP(50 nmol/5μl per mouse)or phosphodies-terase 4 inhibitor rolipram(100 nmol/5μl per mouse).In addition,the ED50of DMED-induced LORR was decreased to 113.6 or 136.5 nmol·kg-1when pre-treated with Gβγsubunits inhibitor M119(100 mg·kg-1) or gallein(100 mg·kg-1)respectively.Administration of dbcAMP,rolipram,gallein or M119 alone had little effect on LORR of mice.Gallein(10 μmol·L-1)significantly inhibited forskolin-stimulated cAMP accumu-lation in CHO-α2A-AR cells.Compared with Gβγsubunits inhibitors or DMED alone,[Ca2+]iand pERK1/2 significantly increased after co-administration of Gβγsubunits inhibitors with DMED.DbcAMP(5 μmol·L-1) or rolipram (5 μmol·L- 1) alone had little effect on ERK1/2 phosphorylation, but decreased DMED-induced ERK1/2 phosphorylation after co-administration with DMED. Gβγsubunit inhibitors treatment increased DMED-induced phosphorylation of CREB, whereas dbcAMP or rolipram had little effect on pCREB induced by DMED.CONCLUSION Gβγsubunits might inhibit DMED-induced sedation through cAMP and pERK1/2 pathway,which was opposite to Gαisubuint.
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Natural product seselin and related derivatives with an angular pyranocoumarin skeleton were synthesized from 8-acetyl-7-hydroxycoumarins by condensation with acetone, reduction, and dehydration successively under mild conditions with total yield of > 50%. Twelve seselin derivatives were tested by the writhing response assay induced by acetic acid at a dose of 40 mg x kg(-1). Seselin (4a) and 4,8,8-trimethyl-9,9-dihydro-pyran[2,3-f] chromene-2,10-dione (2b) showed obviously antinociceptive activity with inhibitory effect of 85% and 50%, respectively, more or quite potent than aspirin in the same assay, suggesting that seselin derivatives could be a novel kind of potential antinociceptive agents.