Methamphetamine decreases K + channel function in human fetal astrocytes by activating the trace amine-associated receptor type-1

Abstract

Methamphetamine (Meth) is a potent and commonly abused psychostimulant. Meth alters neuron and astrocyte activity; yet the underlying mechanism(s) is not fully understood. Here we assessed the impact of acute Meth on human fetal astrocytes (HFAs) using whole-cell patch-clamping. We found that HFAs displayed a large voltage-gated K + efflux (I Kv ) through K v /K v -like channels during membrane depolarization, and a smaller K + influx (I kir ) via inward-rectifying K ir /K ir -like channels during membrane hyperpolarization. Meth at a ‘recreational’ (20 μM) or toxic/fatal (100 μM) concentration depolarized resting membrane potential (RMP) and suppressed I Kv/Kv-like . These changes were associated with a decreased time constant (Ƭ), and mimicked by blocking the two-pore domain K + (K 2P )/K 2P -like and K v /K v -like channels, respectively. Meth also diminished I Kir/Kir-like , but only at toxic/fatal levels. Given that Meth is a potent agonist for the trace amine-associated receptor type-1 (TAAR1), and TAAR1-coupled cAMP/cAMP-activated protein kinase (PKA) cascade, we further evaluated whether the Meth impact on K + efflux was mediated by this pathway. We found that antagonizing TAAR1 with N-(3-Ethoxyphenyl)-4-(1-pyrrolidinyl)-3-(trifluoromethyl)benzamide (EPPTB) reversed Meth-induced suppression of I Kv/Kv-like ; and inhibiting PKA activity by H89 abolished Meth effects on suppressing I Kv/Kv-like . Antagonizing TAAR1 might also attenuate Meth-induced RMP depolarization. Voltage-gated Ca 2+ currents were not detected in HFAs. These novel findings demonstrate that Meth suppresses I Kv/Kv-like by facilitating the TAAR1/G s /cAMP/PKA cascade and altering the kinetics of K v /K v -like channel gating, but reduces K 2P /K 2P -like channel activity through other pathway(s), in HFAs. Given that Meth-induced decrease in astrocytic K + efflux through K 2P /K 2P -like and K v /K v -like channels reduces extracellular K + levels, such reduction could consequently contribute to a decreased excitability of surrounding neurons. Open science badges: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/. (Figure presented.).