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Comparison of effects of tetrahydropalmatine enantiomers on firing activity of dopamine neurons in substantia nigra pars compacta.
Zhongguo Yao Li Xue Bao. 1992 Jul; 13(4):292-7.ZY

Abstract

Extracellular single unit recording techniques were used to elucidate the effects of enantiomers of tetrahydropalmatine (THP) on the firing activity of dopamine (DA) neurons in substantia nigra pars compacta (SNC). (-)-THP rapidly reversed the apomorphine (Apo)-induced inhibition of the SNC DA cell firing activity (ED50 = 0.77, 0.52-1.14, mg.kg-1), while much larger doses of (+)-THP were required to reverse the Apo-induced inhibition (ED50 = 23, 15.2-34.7, mg.kg-1) and the maximal reversal caused by (+)-THP was 79 +/- 9% of the basal firing rate. In paralyzed rats, (-)-THP (0.5-16 mg.kg-1) significantly increased the spontaneous firing rate of SNC DA neurons dose-dependently, while (+)-THP did not until the dose reached 16 mg.kg-1. Pretreatment with (-)-THP 4 mg.kg-1 attenuated Apo-induced inhibition of SNC DA cell firing rate, while (+)-THP 32 mg.kg-1 revealed a similar potency to block the Apo-induced inhibition. In addition, (+)-THP did not potentiate the effect caused by d-amphetamine (Amp) as some behavioral experiments have shown, but large dose of (+)-THP (32 mg.kg-1) blocked the Amp-induced inhibition of SNC DA cell firing activity as (-)-THP (4 mg.kg-1) did. These results suggest that the interaction between D2 receptors and THP enantiomers has stereoselectivity and that (-)-THP is a D2 antagonist while (+)-THP seems to be not.

Authors+Show Affiliations

Shanghai Institute of Materia Medica, Chinese Academy of Sciences.No affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

1360741

Citation

Sun, B C., et al. "Comparison of Effects of Tetrahydropalmatine Enantiomers On Firing Activity of Dopamine Neurons in Substantia Nigra Pars Compacta." Zhongguo Yao Li Xue Bao = Acta Pharmacologica Sinica, vol. 13, no. 4, 1992, pp. 292-7.
Sun BC, Huang KX, Jin GZ. Comparison of effects of tetrahydropalmatine enantiomers on firing activity of dopamine neurons in substantia nigra pars compacta. Zhongguo Yao Li Xue Bao. 1992;13(4):292-7.
Sun, B. C., Huang, K. X., & Jin, G. Z. (1992). Comparison of effects of tetrahydropalmatine enantiomers on firing activity of dopamine neurons in substantia nigra pars compacta. Zhongguo Yao Li Xue Bao = Acta Pharmacologica Sinica, 13(4), 292-7.
Sun BC, Huang KX, Jin GZ. Comparison of Effects of Tetrahydropalmatine Enantiomers On Firing Activity of Dopamine Neurons in Substantia Nigra Pars Compacta. Zhongguo Yao Li Xue Bao. 1992;13(4):292-7. PubMed PMID: 1360741.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Comparison of effects of tetrahydropalmatine enantiomers on firing activity of dopamine neurons in substantia nigra pars compacta. AU - Sun,B C, AU - Huang,K X, AU - Jin,G Z, PY - 1992/7/1/pubmed PY - 1992/7/1/medline PY - 1992/7/1/entrez SP - 292 EP - 7 JF - Zhongguo yao li xue bao = Acta pharmacologica Sinica JO - Zhongguo Yao Li Xue Bao VL - 13 IS - 4 N2 - Extracellular single unit recording techniques were used to elucidate the effects of enantiomers of tetrahydropalmatine (THP) on the firing activity of dopamine (DA) neurons in substantia nigra pars compacta (SNC). (-)-THP rapidly reversed the apomorphine (Apo)-induced inhibition of the SNC DA cell firing activity (ED50 = 0.77, 0.52-1.14, mg.kg-1), while much larger doses of (+)-THP were required to reverse the Apo-induced inhibition (ED50 = 23, 15.2-34.7, mg.kg-1) and the maximal reversal caused by (+)-THP was 79 +/- 9% of the basal firing rate. In paralyzed rats, (-)-THP (0.5-16 mg.kg-1) significantly increased the spontaneous firing rate of SNC DA neurons dose-dependently, while (+)-THP did not until the dose reached 16 mg.kg-1. Pretreatment with (-)-THP 4 mg.kg-1 attenuated Apo-induced inhibition of SNC DA cell firing rate, while (+)-THP 32 mg.kg-1 revealed a similar potency to block the Apo-induced inhibition. In addition, (+)-THP did not potentiate the effect caused by d-amphetamine (Amp) as some behavioral experiments have shown, but large dose of (+)-THP (32 mg.kg-1) blocked the Amp-induced inhibition of SNC DA cell firing activity as (-)-THP (4 mg.kg-1) did. These results suggest that the interaction between D2 receptors and THP enantiomers has stereoselectivity and that (-)-THP is a D2 antagonist while (+)-THP seems to be not. SN - 0253-9756 UR - https://www.unboundmedicine.com/medline/citation/1360741/Comparison_of_effects_of_tetrahydropalmatine_enantiomers_on_firing_activity_of_dopamine_neurons_in_substantia_nigra_pars_compacta_ L2 - http://www.chinaphar.com/1671-4083/13/292.pdf DB - PRIME DP - Unbound Medicine ER -