Neuropharmacology
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Minocycline is a widely used glial activation inhibitor that could suppress pain-related behaviors in a number of different pain animal models, yet, its analgesic mechanisms are not fully understood. Hyperpolarization-activated cation channel-induced Ih current plays an important role in neuronal excitability and pathological pain. In this study, we investigated the possible effect of minocycline on Ih of substantia gelatinosa neuron in superficial spinal dorsal horn by using whole-cell patch-clamp recording. ⋯ Minocycline also caused a negative shift in the activation curve of Ih, but did not alter the reversal potential. Moreover, minocycline slowed down the inter-spike depolarizing slope and produced a robust decrease in the rate of action potential firing. Together, these results illustrate a novel cellular mechanism underlying minocycline's analgesic effect by inhibiting Ih currents of spinal dorsal horn neurons.
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The medial prefrontal cortex (mPFC) serves executive control functions that are impaired in neuropsychiatric disorders and pain. Therefore, restoring normal synaptic transmission and output is a desirable goal. Group II metabotropic glutamate receptors mGluR2 and mGluR3 are highly expressed in the mPFC, modulate synaptic transmission, and have been targeted for neuropsychiatric disorders. ⋯ Their net effect is decreased pyramidal cell output. Facilitatory effects of a group II antagonist suggest the system may be tonically active to control pyramidal output. Failure to release the inhibitory tone and enhance mPFC output could be a mechanism for the development or persistence of a disease state such as pain.
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GABAA receptors are the major inhibitory neurotransmitter receptors in the brain and are the target for many clinically important drugs such as the benzodiazepines. Benzodiazepines act at the high-affinity binding site at the α+/γ- subunit interface. Previously, an additional low affinity binding site for diazepam located in the transmembrane (TM) domain has been described. ⋯ SJM-3 acts as a more efficient modulator than diazepam at the site in the trans-membrane domain. In contrast to low concentrations of benzodiazepines, SJM-3 modulates both synaptic and extrasynaptic receptors. A detailed exploration of the membrane site may provide the basis for the design and identification of subtype-selective modulatory drugs.
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The main purpose of the present study is to investigate the influence of donepezil, a well-known acetylcholinesterase (AChE) inhibitor, on amyloid-β (Aβ)-associated mitochondrial dysfunction, in order to gain a better understanding of the neuroprotective effects of this clinically used anti-Alzheimer's disease (AD) drug. First, our study verifies the ameliorative effects of donepezil on behavioral deficits in both working memory and anxiety in APP/PS1 double transgenic mice, at a time point that AChE is not inhibited. Meanwhile, we demonstrate that donepezil enhances the resistance of brain mitochondria of APP/PS1 mice to the induction of mitochondrial permeability transition (MPT) by calcium ions. ⋯ In addition, donepezil treatment also significantly blocks the Aβ accumulation in the isolated mitochondria. Our study reported for the first time that the protective effects of donepezil against Aβ-associated mitochondrial dysfunction are closely associated with the reduction of Aβ accumulation in the mitochondria. Above observation led us to assume that, besides potent AChE inhibitory effect, other non-cholinergic mechanisms may be involved in the neuroprotective profiles of donepezil.