Significance of piezo‐type mechanosensitive ion channel component 2 in premature ejaculation: An animal study

Clinical characteristics, allergic response to autologous semen, and desensitization in patients with postorgasmic illness syndrome

Introduction

Postorgasmic illness syndrome (POIS) is rare and includes a cluster of physical and cognitive symptoms that occur after ejaculation. The pathogenesis and effective treatments remain unclear.

Aim

This study aimed to characterize the symptomatology of POIS, study the allergic response of autologous semen in patients and controls, and evaluate the effects of desensitization therapy.

Methods

The clinical characteristics of 24 Chinese patients with POIS were analyzed. Skin prick tests, intracutaneous tests, and specific IgE detection were performed with autologous semen. Five patients were desensitized via subcutaneous injections of autologous semen.

Outcomes

Evaluated outcomes included the clinical features of POIS; scores of the Self-rating Anxiety Scale (SAS), Self-rating Depression Scale (SDS), and visual analog scale (VAS) of symptoms; skin reactions; desensitization with diluted autologous seminal fluid; and the IgE reactivity patterns of immunoblotting and enzyme-linked immunosorbent assay in vitro.

Results

The most common symptom cluster was the general cluster, and the most prevalent symptoms were extreme fatigue and inattention. A total of 66.67% (14/21) of the patients had no symptoms or milder symptoms after nocturnal emission than after intercourse or masturbation. Of the patients, 87.5% (21/24) had psychiatric symptoms and 53.85% (7/13) had abnormal sex hormone levels. The SAS and SDS scores of the high and low VAS groups were significantly higher than those of the control group. Pearson analysis showed that the correlation coefficient between the SAS and VAS was 0.607 (P < .01) and that between the SDS and VAS was 0.490 (P < .05). The patients and healthy donors all had positive intracutaneous test results with their own semen, negative skin prick test results, and no IgE specific to autologous semen. Most patients (4/5) did not achieve ideal therapeutic effects with desensitization.

Clinical Implications

Allergy is not the main pathogenesis of POIS, and desensitization with autologous semen is not effective for most patients.

Strengths and Limitations

This project included the largest number of patients with POIS in China and assessed the allergic response to autologous semen and the effect of desensitization therapy. There is no objective method for evaluating the efficacy of desensitization with autologous semen.

Conclusions

IgE-mediated semen allergy is not the main pathogenesis of POIS, and there is a positive chance that POIS is related to psychological factors. Most patients do not respond to desensitization with autologous semen, and POIS treatment should be individualized, especially in cases with uncertain causes.

Piezo-mediated mechanosensation contributes to stabilizing copulation posture and reproductive success in Drosophila males

In internal fertilization animals, reproductive success depends on maintaining copulation until gametes are transported from male to female. In Drosophila melanogaster, mechanosensation in males likely contributes to copulation maintenance, but its molecular underpinning remains to be identified. Here we show that the mechanosensory gene piezo and its' expressing neurons are responsible for copulation maintenance. An RNA-seq database search and subsequent mutant analysis revealed the importance of piezo for maintaining male copulation posture. piezo-GAL4-positive signals were found in the sensory neurons of male genitalia bristles, and optogenetic inhibition of piezo-expressing neurons in the posterior side of the male body during copulation destabilized posture and terminated copulation. Our findings suggest that the mechanosensory system of male genitalia through Piezo channels plays a key role in copulation maintenance and indicate that Piezo may increase male fitness during copulation in flies.

Current and emerging treatment options for premature ejaculation

Premature ejaculation (PE) is a prevalent male sexual dysfunction. Current standard treatment regimens include behavioural therapies, topical anaesthetics, dapoxetine and other selective serotonin reuptake inhibitors (SSRIs). Most of the pharmacotherapeutic options target neurotransmitters (such as serotonin and oxytocin) that have a role in the ejaculation mechanism. However, these treatments are mildly effective and only provide a temporary delay in the ejaculation latency time, and PE recurs when the treatment is stopped. Thus, a treatment for PE is urgently needed and research is ongoing to find the ideal PE therapy. The efficacy and safety of topical anaesthetics and SSRIs in delaying ejaculation have been confirmed in many well-designed controlled trials. Both preclinical and clinical studies on new-generation SSRIs are ongoing. Moreover, promising results came from clinical trials in which the efficacy of on-demand PE therapies targeting neurotransmitters other than serotonin, such as α1-adrenoceptor antagonists and oxytocin antagonists, was assessed. Surgical intervention and neuromodulation have been proposed as potential treatment options for PE; however, current PE guidelines do not recommend these treatments owing to safety concerns.

Post Orgasmic Illness Syndrome (POIS) and Delayed Onset Muscle Soreness (DOMS): Do They Have Anything in Common?

Post orgasmic illness syndrome is a rare, mysterious condition with an unknown pathomechanism and uncertain treatment. The symptoms of post orgasmic illness syndrome last about 2–7 days after an ejaculation. The current hypothesis proposes that the primary injury in post orgasmic illness syndrome is an acute compression proprioceptive axonopathy in the muscle spindle, as is suspected in delayed onset muscle soreness. The terminal arbor degeneration-like lesion of delayed onset muscle soreness is theorized to be an acute stress response energy-depleted dysfunctional mitochondria-induced impairment of Piezo2 channels and glutamate vesicular release. The recurring symptoms of post orgasmic illness syndrome after each ejaculation are suggested to be analogous to the repeated bout effect of delayed onset muscle soreness. However, there are differences in the pathomechanism, mostly attributed to the extent of secondary tissue damage and to the extent of spermidine depletion. The spermidine depletion-induced differences are as follows: modulation of the acute stress response, flu-like symptoms, opioid-like withdrawal and enhanced deregulation of the autonomic nervous system. The longitudinal dimension of delayed onset muscle soreness, in the form of post orgasmic illness syndrome and the repeated bout effect, have cognitive and memory consequences, since the primary injury is learning and memory-related.

Sensory innervation of the human male prepuce: Meissner's corpuscles predominate

Meissner's corpuscles are the most abundant sensory corpuscles in the glabrous skin of the male prepuce. They are type I, rapidly adapting, low‐threshold mechanoreceptors, and their function is linked to the expression of the mechanoprotein piezo‐type mechanosensitive ion channel component 2 (PIEZO2). Stimulation of genital Meissner's corpuscles gives rise to sexual sensations. It has been recently demonstrated that digital Meissner's corpuscles, Meissner‐like corpuscles, and genital end bulbs have an endoneurium‐like capsule surrounding their neuronal elements; that is, the axon and glial lamellar cells, and their axons, display PIEZO2 immunoreactivity. It is unknown whether this is also the case for preputial Meissner's corpuscles. Furthermore, the expression of certain proteins that have been found in Meissner's corpuscles at other anatomical locations, especially in the digits, has not been investigated in preputial Meissner's corpuscles. Here, we used immunohistochemistry to investigate the expression of axonal (neurofilament, neuron‐specific enolase), glial (S100 protein, glial fibrillary acidic protein, vimentin), endoneurial (CD34), and perineurial (glucose transporter 1) markers in the preputial and digital Meissner's corpuscles of male participants aged between 5 and 23 years. Furthermore, we investigated the occurrence of the mechanoprotein PIEZO2 in male preputial Meissner's corpuscles. Human male prepuce contains numerous Meissner's corpuscles, which may be grouped or isolated and are regularly distributed in the dermal papillae. Lamellar glial cells display strong expression of S100 protein and vimentin but lack expression of glial fibrillary acidic protein. In addition, they show axonal PIEZO2 expression and have an endoneurial capsule, but no perineurial. Our results indicate that human male preputial Meissner's corpuscles share the immunohistochemical profile of digital Meissner's corpuscles, which is considered to be necessary for mechanotransduction. These data strongly suggest that the structure and function of Meissner's corpuscles are independent of their anatomical location.