Loss of auditory activity modifies the location of potassium channel KCNQ5 in auditory brainstem neurons

Regulation of Neurotransmitter Release by K+ Channels

K+ channels play potent roles in the process of neurotransmitter release by influencing the action potential waveform and modulating neuronal excitability and release probability. These diverse effects of K+ channel activation are ensured by the wide variety of K+ channel genes and their differential expression in different cell types. Accordingly, a variety of K+ channels have been implicated in regulating neurotransmitter release, including the Ca2+- and voltage-gated K+ channel Slo1 (also known as BK channel), voltage-gated K+ channels of the Kv3 (Shaw-type), Kv1 (Shaker-type), and Kv7 (KCNQ) families, G-protein-gated inwardly rectifying K+ (GIRK) channels, and SLO-2 (a Ca2+-. Cl-, and voltage-gated K+ channel in C. elegans). These channels vary in their expression patterns, subcellular localization, and biophysical properties. Their roles in neurotransmitter release may also vary depending on the synapse and physiological or experimental conditions. This chapter summarizes key findings about the roles of K+ channels in regulating neurotransmitter release.

KCNQ Potassium Channels as Targets of Botanical Folk Medicines

Since prehistory, human species have depended on plants for both food and medicine. Even in countries with ready access to modern medicines, alternative treatments are still highly regarded and commonly used. Unlike modern pharmaceuticals, many botanical medicines are in widespread use despite a lack of safety and efficacy data derived from controlled clinical trials and often unclear mechanisms of action. Contributing to this are the complex and undefined composition and likely multifactorial mechanisms of action and multiple targets of many botanical medicines. Here, we review the newfound importance of the ubiquitous KCNQ subfamily of voltage-gated potassium channels as targets for botanical medicines, including basil, capers, cilantro, lavender, fennel, chamomile, ginger, and Camellia, Sophora, and Mallotus species. We discuss the implications for the traditional use of these plants for disorders such as seizures, hypertension, and diabetes and the molecular mechanisms of plant secondary metabolite effects on KCNQ channels.

Impact of cochlear ablation on calretinin and synaptophysin in the gerbil anteroventral cochlear nucleus before the hearing onset

Mammalian auditory system undergoes many structural and functional modifications during postnatal development, which are dependent on the relationship between auditory nerve fibers and their nuclei. In the present study, the cochlea of Meriones unguiculatus was ablated unilaterally on postnatal day 5 or 9 (P5 or P9), before the onset of hearing. Histochemical analysis of synaptophysin (SYN) and calretinin (CR) in anterior anteroventral cochlear nucleus (AVCN-A) was performed to analyze whether unilateral cochlea ablation induces changes in the auditory terminal endings and somata of spherical bushy cells (SBCs). During the period of postnatal development, CR-labeling was evident in somata of SBCs and in auditory nerve terminals. SYN was most apparent in puncta encircled cell bodies, progressing with age. Cochlear removal at P5 induced a decrease in CR-labeling in SBCs somata 6 h and 48 h post-lesion; whereas, ablation at P9 increased the somatic CR-labeling in the lesioned AVCN-A after 24 and 48 h post-lesion. The SYN-labeled synaptic puncta were remarkably reduced in the AVCN-A of P5- and P9-cochlea-ablated gerbils with stronger effects in P5 animals (a 50% reduction after 48 h). Interestingly, a significant increase in the SYN-immunolabeled puncta was found after 48 h compared to 24 h in the lesioned AVCN-A of P9 gerbils, indicating reactive synaptogenesis. Our study shows, that following the destruction of the cochlea at different postnatal periods, the CR- and SYN-labeling are differentially influenced in the AVCN-A, which in turn coincides with different critical developmental periods before the onset of hearing.