Department of Biomedical Sciences, Macquarie University, Sydney, Australia.
Cannabis Cannabinoid Res. 2022 Feb;7(1):34-45. doi: 10.1089/can.2020.0134. Epub 2021 Jan 21.
Low voltage-activated T-type calcium channels (T-type ), Ca3.1, Ca3.2, and Ca3.3, are opened by small depolarizations from the resting membrane potential in many cells and have been associated with neurological disorders, including absence epilepsy and pain. Δ-tetrahydrocannabinol (THC) is the principal psychoactive compound in and also directly modulates T-type ; however, there is no information about functional activity of most phytocannabinoids on T-type calcium channels, including Δ-tetrahydrocannabinolic acid (THCA), the natural nonpsychoactive precursor of THC. The aim of this work was to characterize THCA effects on T-type calcium channels. We used HEK293 Flp-In-TREx cells stably expressing Ca3.1, 3.2, or 3.3. Whole-cell patch clamp recordings were made to investigate cannabinoid modulation of . THCA and THC inhibited the peak current amplitude Ca3.1 with ECs of 6.0±0.7 and 5.6±0.4, respectively. THC (1 μM) or THC produced a significant negative shift in half activation and inactivation of Ca3.1, and both drugs prolonged Ca3.1 deactivation kinetics. THCA (10 μM) inhibited Ca3.2 by 53%±4%, and both THCA and THC produced a substantial negative shift in the voltage for half inactivation and modest negative shift in half activation of Ca3.2. THC prolonged the deactivation time of Ca3.2, while THCA did not. THCA inhibited the peak current of Ca3.3 by 43%±2% (10 μM) but did not notably affect Ca3.3 channel activation or inactivation; however, THC caused significant hyperpolarizing shift in Ca3.3 steady-state inactivation. THCA modulated T-type currents , with significant modulation of kinetics and voltage dependence at low μM concentrations. This study suggests that THCA may have potential for therapeutic use in pain and epilepsy through T-type calcium channel modulation without the unwanted psychoactive effects associated with THC.
低电压激活 T 型钙通道(T 型),Ca3.1、Ca3.2 和 Ca3.3,在许多细胞中,通过从静息膜电位的小去极化而被打开,并且与包括失神性癫痫和疼痛在内的神经紊乱有关。Δ-四氢大麻酚(THC)是 的主要精神活性化合物,并且还直接调节 T 型;然而,对于 T 型钙通道的大多数植物大麻素的功能活性,包括Δ-四氢大麻酸(THCA),没有信息,THCA 是 THC 的天然非精神活性前体。本工作的目的是表征 THCA 对 T 型钙通道的作用。我们使用稳定表达 Ca3.1、3.2 或 3.3 的 HEK293 Flp-In-TREx 细胞进行全细胞贴片钳记录,以研究大麻素对 的调制。THCA 和 THC 抑制了 Ca3.1 的峰值电流幅度,EC50 分别为 6.0±0.7 和 5.6±0.4。THC(1 μM)或 THC 导致 Ca3.1 的半数激活和失活的显著负移,并且两种药物均延长了 Ca3.1 的失活动力学。THCA(10 μM)抑制 Ca3.2 达 53%±4%,THCA 和 THC 均导致 Ca3.2 的半数失活和半数激活的显著负移,并且 THC 延长了 Ca3.2 的失活时间,而 THCA 没有。THCA 抑制 Ca3.3 的峰值电流 43%±2%(10 μM),但对 Ca3.3 通道的激活或失活没有显著影响;然而,THC 导致 Ca3.3 稳态失活的显著超极化移位。THCA 调制 T 型电流,在低 μM 浓度下,动力学和电压依赖性有显著调制。本研究表明,THCA 可能通过 T 型钙通道调制而在没有与 THC 相关的不良精神活性作用的情况下,在疼痛和癫痫中具有治疗用途的潜力。