Commonality and heterogeneity of pacemaker mechanisms in the male reproductive organs.

During emission, the first phase of ejaculation, smooth muscle in organs of the male reproductive tract (MRT) vigorously contract upon sympathetic nerve excitation to expel semen consisting of sperm and seminal plasma. During inter-ejaculation phases, the epididymis, seminal vesicles and prostate undergo spontaneous phasic contractions (SPCs), this transporting and maintaining the quality of sperm and seminal plasma. Recent studies have revealed platelet-derived growth factor receptor α-expressing (PDGFRα) subepithelial interstitial cells in seminal vesicles subserve the role of pacemaker cells that electrically drive SPCs in this organ.

PDGFRα subepithelial interstitial cells act as a pacemaker to drive smooth muscle of the guinea pig seminal vesicle.

Smooth muscle cells (SMCs) of the guinea pig seminal vesicle (SV) develop spontaneous phasic contractions, Ca flashes and electrical slow waves in a mucosa-dependent manner, and thus it was envisaged that pacemaker cells reside in the mucosa. Here, we aimed to identify the pacemaker cells in SV mucosa using intracellular microelectrode and fluorescence Ca imaging techniques. Morphological characteristics of the mucosal pacemaker cells were also investigated using focused ion beam/scanning electron microscopy tomography and fluorescence immunohistochemistry.

Virus database annotations assist in tracing information on patients infected with emerging pathogens.

The global pandemic of SARS-CoV-2 has disrupted human social activities. In restarting economic activities, successive outbreaks by new variants are concerning. Here, we evaluated the applicability of public database annotations to estimate the virulence, transmission trends and origins of emerging SARS-CoV-2 variants.

Expression of the pacemaker channel HCN4 in excitatory interneurons in the dorsal horn of the murine spinal cord.

In the central nervous system, hyperpolarization-activated, cyclic nucleotide-gated (HCN1-4) channels have been implicated in neuronal excitability and synaptic transmission. It has been reported that HCN channels are expressed in the spinal cord, but knowledge about their physiological roles, as well as their distribution profiles, appear to be limited. We generated a transgenic mouse in which the expression of HCN4 can be reversibly knocked down using a genetic tetracycline-dependent switch and conducted genetically validated immunohistochemistry for HCN4.

Properties of SK3 channel-expressing PDGFRα (+) cells in the rodent urinary bladder.

Localisation of platelet-derived growth factor receptor-α (PDGFRα) (+) cells expressing small-conductance Ca-activated K (SK3) channels in the urinary bladder was investigated, while putative roles of SK3 (+) PDGFRα (+) cells in suppressing detrusor smooth muscle (DSM) spontaneous activity were explored. In guinea-pig bladder, immunohistochemistry for SK3 channels, PDGFRα or vimentin was examined, as were the effects of purinergic agonists on spontaneous phasic contractions (SPCs). In bladder of PDGFRα-GFP mice, the effects of purinergic agonists on intracellular Ca signaling in PDGFRα (+) cells or DSM cells in situ and SPCs were investigated.

Mucosa-Dependent, Stretch-Sensitive Spontaneous Activity in Seminal Vesicle.

Seminal vesicles (SVs), a pair of male accessory glands, contract upon sympathetic nerve excitation during ejaculation while developing spontaneous phasic constrictions in the inter-ejaculatory storage phase. Recently, the fundamental role of the mucosa in generating spontaneous activity in SV of the guinea pig has been revealed. Stretching the mucosa-intact but not mucosa-denuded SV smooth muscle evokes spontaneous phasic contractions arising from action potential firing triggered by electrical slow waves and associated Ca flashes.

Role of mucosa in generating spontaneous activity in the guinea pig seminal vesicle.

Key Points: The mucosa may have neuron-like functions as urinary bladder mucosa releases bioactive substances that modulate sensory nerve activity as well as detrusor muscle contractility. However, such mucosal function in other visceral organs remains to be established. The role of mucosa in generating spontaneous contractions in seminal vesicles (SVs), a paired organ in the male reproductive tract, was investigated.

Effects of Silodosin and Tamsulosin on the Seminal Vesicle Contractile Response.

Objectives: To understand the mechanisms underlying ejaculation dysfunction caused by α1A-adrenocetor (AR) antagonists, the effects of α1A-AR antagonists on the contractile responses of the seminal vesicle were investigated.

Methods: Isolated seminal vesicles from guinea pigs were cannulated and pressurized, and the changes in the intraluminal pressure were recorded. Periodic applications of electrical stimulation (ES) caused biphasic increase in the intraluminal pressure, that is, initial and subsequent contractions.

Function and expression pattern of TRPM8 in bladder afferent neurons associated with bladder outlet obstruction in rats.

We investigated the function and expression pattern of the transient receptor potential melastatin-8 (TRPM8) in urinary bladder afferent neurons from control and bladder outlet obstruction (BOO) rats. BOO was produced and, after six weeks, the effects of intravesical infusion of menthol, the agonist of TRPM8, were investigated using unanesthetized cystometry. The intravesical infusion of menthol produced an increase in the micturition pressure in both sham surgery and BOO rats.

Effects of emodin on synaptic transmission in rat hippocampal CA1 pyramidal neurons in vitro.

Rhubarb extracts provide neuroprotection after brain injury, but the mechanism of this protective effect is not known. The present study tests the hypothesis that rhubarb extracts interfere with the release of glutamate by brain neurons and, therefore, reduce glutamate excitotoxicity. To this end, the effects of emodin, an anthraquinone derivative extracted from Rheum tanguticum Maxim.

L-arginine enhances heat-induced depression of neuronal activity in the rat hippocampal CA1 area.

Effects of L-arginine on the heat-induced depression of the neuronal activity in the hippocampal CA1 area were investigated using optical recording techniques. An increase in the temperature of hippocampal neurons from 32 degrees C to 38 degrees C reversibly depressed the fast and slow components of the optical response to stimulation of the Schaffer collaterals that correspond to the presynaptic action potential and excitatory postsynaptic response, respectively. The neuronal activity recovered almost completely after cooling the hippocampal neurons back to 32 degrees C.

Contribution of nitric oxide to the depression of neuronal activity induced by temperature increase in the rat hippocampal CA1 area.

Using optical recording techniques, we examined whether nitric oxide (NO) is implicated in the impairment of the activity of hippocampal CA1 neurons induced by mild heat stress. A temperature increase from 32 to 38 degrees C reversibly depressed the neuronal activity in hippocampal slices. L-Arginine (1 mM), an NO donor, enhanced the heat-induced depression of the activity of hippocampal CA1 neurons.

Effects of temperature increase on the propagation of presynaptic action potentials in the pathway between the Schaffer collaterals and hippocampal CA1 neurons.

Effects of temperature increase on the neuronal activity of hippocampal CA2-CA1 regions were examined by using optical and electrophysiological recording techniques. Stimulation of the Schaffer collaterals at the CA2 region evoked depolarizing optical signals that spread toward the CA1 region at 32 degrees C. The optical signal recorded by 49 pixels was characterized by fast and slow components that were closely related to presynaptic action potentials and excitatory postsynaptic responses, respectively.