Abnormal cortical surface-based spontaneous and functional connectivity in the whole brain in lifelong premature ejaculation patients.

Recent research has highlighted structural and functional abnormalities in the cerebral cortex of patients with premature ejaculation (PE). These anomalies could play a pivotal role in the physiological mechanisms underlying PE. This study leveraged functional magnetic resonance imaging (fMRI), a noninvasive technique, to explore these neural mechanisms. We conducted resting-state fMRI scans on 36 PE patients and 22 healthy controls (HC), and collected data on Premature Ejaculation Diagnostic Tool (PEDT) scores and intravaginal ejaculation latency time (IELT). Employing a surface-based regional homogeneity (ReHo) approach, we analyzed local neural synchronous spontaneous activity, diverging from previous studies that utilized a volume-based ReHo method. Areas with significant ReHo differences between PE and HC groups underwent surface-based functional connectivity (FC) analysis. Significant discrepancies in ReHo and FC across the cortical surface were observed in the PE cohort. Notably, PE patients exhibited decreased ReHo in the left triangular inferior frontal gyrus and enhanced ReHo in the right middle frontal gyrus. The latter showed heightened connectivity with the left lingual gyrus and the right orbital superior frontal gyrus. Furthermore, a correlation between ReHo and FC values with PEDT scores and IELT was found in the PE group. Our findings, derived from surface-based fMRI data, underscore specific brain regions linked to the neurobiological underpinnings of PE.

The application of intraoperative neurophysiological monitoring in selective dorsal neurotomy for primary premature ejaculation: a prospective single-center study.

Selective dorsal neurotomy (SDN) is a surgical treatment for primary premature ejaculation (PE), but there is still no standard surgical procedure for selecting the branches of the dorsal penile nerves to be removed. We performed this study to explore the value of intraoperative neurophysiological monitoring (IONM) of the penile sensory-evoked potential (PSEP) for standard surgical procedures in SDN. One hundred and twenty primary PE patients undergoing SDN were selected as the PE group and 120 non-PE patients were selected as the normal group. The PSEP was monitored and compared between the two groups under both natural and general anesthesia (GA) states. In addition, patients in the PE group were randomly divided into the IONM group and the non-IONM group. During SDN surgery, PSEP parameters of the IONM group were recorded and analyzed. The differences in PE-related outcome measurements between the perioperative period and 3 months' postoperation were compared for the PE patients, and the differences in effectiveness and complications between the IONM group and the non-IONM group were compared. The results showed that the average latency of the PSEP in the PE group was shorter than that in the normal group under both natural and GA states (P < 0.001). Three months after surgery, the significant effective rates in the IONM and non-IONM groups were 63.6% and 34.0%, respectively (P < 0.01), and the difference in complications between the two groups was significant (P < 0.05). IONM might be useful in improving the short-term therapeutic effectiveness and reducing the complications of SDN.

Inhibitory Role of Gamma-Aminobutyric Receptors in Paraventricular Nucleus on Ejaculatory Responses in Rats.

BACKGROUND: Although abnormal sympathetic nerve system (SNS) activity has been demonstrated in the pathogenesis of ejaculation disorders, few data are available on its underlying mechanism. AIM: To investigate whether differences in ejaculatory behavior of rats were associated with the state of SNS activity and gamma-aminobutyric (GABA) receptor expressions in the paraventricular nucleus (PVN) of the hypothalamus and the effects of GABA receptors in the PVN on ejaculatory behavior. METHODS: Based on ejaculatory performance, Sprague-Dawley rats were divided into "sluggish," "normal," and "rapid" ejaculators. PVN microinjection was performed to evaluate the role of GABA receptors on sexual behavior. OUTCOMES: The outcomes include differences in expression and distribution of GABA receptors and norepinephrine level among the 3 groups and changes in copulation behavior parameters after PVN microinjection. RESULTS: Compared with "normal" rats, the "rapid" group ejaculated more times with shorter latency (P < .001, P < .001) and had lower expression and distribution of both GABA-A and GABA-B receptors, while the opposed results appeared in the "sluggish" group. The norepinephrine level was successively increased among "sluggish," "normal," and "rapid" rats (P < .001) and correlated with ejaculation frequency (r = 0.896, P < .001) and ejaculation latency (r = -0.835, P < .001). In addition, bilateral microinjection of the GABA-A and GABA-B receptor agonist (isoguvacine and baclofen) into the PVN both significantly prolonged the intromission latency and inhibited ejaculation, which could be blocked by antagonist gabazine and CGP-35348, respectively. Vigabatrin, the GABA-transaminase inhibitor, caused a significantly reduced ejaculation frequency and extended ejaculation latency in rats, which could be offset by simultaneous injections of gabazine and CGP-35348. CLINICAL IMPLICATIONS: Our findings provide new understanding about GABA receptors in the PVN on sexual behavior and enhance the comprehension of neurobiological mechanisms involved in premature ejaculation. STRENGTHS & LIMITATIONS: Our results have indicated that GABA receptors in the PVN may inhibit ejaculation through restraining the activity of SNS. However, our study did not analyze the changes of GABA receptors in other brain areas, which needs further study. CONCLUSION: Ejaculation behaviors in male rats are associated with SNS activity and could be regulated by GABA receptors in the PVN, which may be of assistance in the treatment of ejaculation disorders in the future. Zhang QJ, Yang BB, Yang J, et al. Inhibitory Role of Gamma-Aminobutyric Receptors in Paraventricular Nucleus on Ejaculatory Responses in Rats. J Sex Med 2020;17:614-622.

Correction: Epalrestat, an Aldose Reductase Inhibitor, Restores Erectile Function in Streptozocin-induced Diabetic Rats.

This Article was originally published under Nature Research's License to Publish, but has now been made available under a CC BY 4.0 license. The PDF and HTML versions of the Article have been modified accordingly.

Epalrestat, an Aldose Reductase Inhibitor, Restores Erectile Function in Streptozocin-induced Diabetic Rats.

Epalrestat, an aldose reductase inhibitor (ARI), was adopted to improve the function of peripheral nerves in diabetic patients. The aim of this study was to investigate whether epalrestat could restore the erectile function of diabetic erectile dysfunction using a rat model. From June 2016, 24 rats were given streptozocin (STZ) to induce the diabetic rat model, and epalrestat was administered to ten diabetic erectile dysfunction (DED) rats. Intracavernous pressure (ICP) and mean systemic arterial pressure (MAP), levels of aldose reductase (AR), nerve growth factor (NGF), neuronal nitric oxide synthase (nNOS), α-smooth muscle antigen (α-SMA), and von Willebrand factor (vWF) in the corpus cavernosum were analyzed. We discovered that epalrestat acted on cavernous tissue and partly restored erectile function. NGF and nNOS levels in the corpora were increased after treatment with epalrestat. We also found that the content of α-SMA-positive smooth muscle cells and vWF-positive endothelial cells in the corpora cavernosum were declined. Accordingly, epalrestat might improve erectile function by increasing the upregulation of NGF and nNOS to restore the function of the dorsal nerve of the penis.

Pancreatic kininogenase improves erectile function in streptozotocin-induced type 2 diabetic rats with erectile dysfunction.

Erectile dysfunction (ED) associated with type 2 diabetes is a severe problem that requires effective treatment. Pancreatic kininogenase (PK) has the potential to improve the erectile function of ED patients. This study aims to investigate the effect of PK on erectile function in streptozotocin-induced type 2 diabetic ED rats. To achieve this goal, we divided male Sprague-Dawley rats into five groups. One group was not treated, and the other four groups were treated with saline, sildenafil, PK or sildenafil, and PK, respectively, for 4 weeks after the induction of type 2 diabetic ED. Then, intracavernous pressure under cavernous nerve stimulation was measured, and penile tissue was collected for further study. Endothelial nitric oxide synthase levels, smooth muscle content, endothelium content, cyclic guanosine monophosphate (cGMP) levels in the corpus cavernosum, and neuronal nitric oxide synthase levels in the dorsal penile nerve were measured. Improved erectile function and endothelium and smooth muscle content in the corpus cavernosum were observed in diabetic ED rats. When treating diabetic ED rats with PK and sildenafil at the same time, a better therapeutic effect was achieved. These data demonstrate that intraperitoneal injection of PK can improve erectile function in a rat model of type 2 diabetic ED. With further research on specific mechanisms of erectile function improvement, PK may become a novel treatment for diabetic ED.

Differences in sympathetic nervous system activity and NMDA receptor levels within the hypothalamic paraventricular nucleus in rats with differential ejaculatory behavior.

Differences in intravaginal ejaculation latency reflect normal biological variation, but the causes are poorly understood. Here, we investigated whether variation in ejaculation latency in an experimental rat model is related to altered sympathetic nervous system (SNS) activity and expression of N-methyl-D-aspartic acid (NMDA) receptors in the paraventricular nucleus of the hypothalamus (PVN). Male rats were classified as "sluggish," "normal," and "rapid" ejaculators on the basis of ejaculation frequency during copulatory behavioral testing. The lumbar splanchnic nerve activity baselines in these groups were not significantly different at 1460 ± 480 mV, 1660 ± 600 mV, and 1680 ± 490 mV, respectively (P = 0.71). However, SNS sensitivity was remarkably different between the groups (P < 0.01), being 28.9% ± 8.1% in "sluggish," 48.4% ± 7.5% in "normal," and 88.7% ± 7.4% in "rapid" groups. Compared with "normal" ejaculators, the percentage of neurons expressing NMDA receptors in the PVN of "rapid" ejaculators was significantly higher, whereas it was significantly lower in "sluggish" ejaculators (P = 0.01). In addition, there was a positive correlation between the expression of NMDA receptors in the PVN and SNS sensitivity (r = 0.876, P = 0.02). This study shows that intravaginal ejaculatory latency is associated with SNS activity and is mediated by NMDA receptors in the PVN.

No effect of abstinence time on nerve electrophysiological test in premature ejaculation patients.

The nerve electrophysiological tests may differentiate the treatment of primary premature ejaculation (PPE) in our previous studies. However, no study verifies if the results will be affected by abstinence time. From January to December in 2016, fifty PPE patients ejaculated within 2 min and 28 control subjects were enrolled. The nerve electrophysiological tests, including dorsal nerve somatosensory evoked potential (DNSEP), glans penis somatosensory evoked potential (GPSEP), and penile sympathetic skin response (PSSR), were recorded before and immediately after ejaculation. The abstinence day was not correlated with the latencies of SEPs or PSSR neither in PE group (P = 0.170, 0.064, and 0.122, respectively) nor in control group (P = 0.996, 0.475, and 0.904, respectively). No statistically differences were found in the latencies of SEPs and PSSR before and after ejaculation in PE patients (P = 0.439, 0.537, and 0.576, respectively) or control subjects (P = 0.102, 0.198, and 0.363, respectively). Thus, abstinence time does not interfere with the nerve electrophysiological test, which is stable in determining the nerve function of PPE patients.

[Establishment of an animal model of primary premature ejaculation].

OBJECTIVE: To investigate the feasibility and practicability of establishing an animal model of primary premature ejaculation using the ejaculation distribution theory. METHODS: We induced behavioral estrus in 32 ovariectomized female SD rats by subcutaneous injection of 20 µg estradiol benzoate at 48 hours and 500 µg progesterone at 4 hours before mating them with 49 male rats once a week for six times. During the last three opulations, we observed the male animals for mounting latency (ML), intromission latency (IL), ejaculation latency (EL), postejaculation interval (PEI), mounting frequency (MF), intromission frequency (IF), intromission rate (IR), and ejaculation frequency (EF). RESULTS: Finally, 22 of the male rats were included in this study. The mean EF>33 was deemed rapid ejaculation,EF<1 sluggish ejaculation, and EF 1.5－2.5 normal ejaculation. The EL was significantly shorter in the rapid ejaculation group than in the sluggish and normal ejaculation groups. The IF was the lowest in those with rapid ejaculation. No statistically significant differences were observed in the ML among the three groups of rats. CONCLUSIONS: Based on the mean ejaculation frequency, the male rats with rapid ejaculation were easily screened, and this animal model may play an important role in exploring the mechanisms of primary premature ejaculation.