Idiosyncratic Heart Rate Response in Men during Sexual Arousal

Rapid ejaculator rats are more susceptible to anxiety compared with normal ejaculator rats

By observation of Sprague-Dawley male rats with different ejaculatory behaviors, we have identified distinct behavioral characteristics in rapid ejaculator rats. To validate these differential behaviors, we conducted multifaceted behavioral experiments on rapid ejaculator rats and normal rats. Through mating experiments, 42 male rats were categorized into 5 rapid ejaculator rats, 29 normal ejaculator rats, and 8 sluggish ejaculator rats according to their ejaculation frequency. We selected 5 rats exhibiting rapid ejaculation and 5 rats with normal ejaculation for participation in the Morris water maze, open-field test, and balance beam experiments. The open-field tests revealed that rapid ejaculator rats spent shorter time in the center region (1.23 ± 1.21 vs. 6.56 ± 2.40 s, P = 0.0041), less entered the center region (0.80 ± 0.75 vs. 3.40 ± 1.50, time, P = 0.0145), traveled shorter distances (17,003.77 ± 3339.42 vs. 25,037.90 ± 5499.94 mm, P = 0.0371), and had a lower average speed compared with normal rats (66.09 ± 62.36 vs. 195.56 ± 83.41 mm/s, P = 0.0377). However, no significant differences were observed in the Morris water maze and balance beam experiments (0.25 ± 0.05 vs. 0.26 ± 0.07, P = 0.7506;16.40 ± 3.77 vs. 16.25 ± 2.05, P = 0.9515). These behavioral results indicated that the rapid ejaculator rats were more prone to anxiety. To further substantiate this claim, we examined Brain-derived neurotrophic factor expression levels in the hippocampus of rat brains using immunohistochemistry and western blotting. The results demonstrate lower Brain-derived neurotrophic factor expression in the hippocampus of rapid ejaculator rats compared with that in normal rats (P = 0.0093). Thus, our experiments indicate that rapid ejaculator rats exhibit a higher propensity for anxiety, potentially linked to their abnormal neurophysiologic state. It is concluded that rapid ejaculator rats may be more susceptible to anxiety on a pathophysiological basis.

Orexin receptors in paraventricular nucleus influence sexual behavior via regulating the sympathetic outflow in males

BACKGROUND

Orexins are hypothalamic neuropeptides associated with various neurophysiological activities such as sleep, arousal, and reward. However, there are few studies investigating the relationships between orexin receptors in the paraventricular nucleus and sexual behaviors.

OBJECTIVES

To explore the roles of orexin receptors in the paraventricular nucleus on sexual behaviors and uncover its potential mechanisms in males.

MATERIALS AND METHODS

Orexin A, orexin 1 receptor antagonist SB334867, and orexin 2 receptor antagonist TCS-OX2-29 were microinjected into the paraventricular nucleus to investigate the effects of orexin receptors on copulatory behavior testing of C57BL/6 mice. To explore if ejaculation could activate orexin 1 receptor-expressing neurons in the paraventricular nucleus, fluorescence immunohistochemical double staining was utilized. The levels of serum norepinephrine were measured and the lumbar sympathetic nerve activity was recorded to reflect the sympathetic nervous system activity. Moreover, the bulbospongiosus muscle-electromyogram was recorded and analyzed. To test whether perifornical/lateral hypothalamic area orexinergic neurons directly projected to the paraventricular nucleus, virus retrograde tracing technology was utilized.

RESULTS

Orexin A significantly enhanced sexual performance by shortening the intromission and ejaculation latencies, and increasing the mount and intromission frequencies, while the opposite outcomes appeared with SB334867. However, TCS-OX2-29 had no significant effects on sexual behaviors. Moreover, orexin A increased lumbar sympathetic nerve activity and the levels of serum norepinephrine, while SB334867 decreased lumbar sympathetic nerve activity and norepinephrine, which caused a significant decrease in sympathetic nervous system outflow. Meanwhile, a robust increase in the bulbospongiosus muscle-electromyogram activity was identified after microinjecting orexin A. Furthermore, cFos immunopositive cells were increased and double stained with orexin 1 receptor-expressing neurons in the mating group. Additionally, the retrograde tracing results demonstrated that orexinergic neurons in the perifornical/lateral hypothalamic area directly projected to the paraventricular nucleus.

CONCLUSIONS

Orexin 1 receptor in the paraventricular nucleus could influence the ejaculatory reflex via mediating the sympathetic nervous system activity, which might be of great importance in the treatment of premature ejaculation in the future.

A Study of Differences in Penile Dorsal Nerve Somatosensory Evoked Potential Testing Among Healthy Controls and Patients With Primary and Secondary Premature Ejaculation

BACKGROUND

Penile dorsal nerve somatosensory evoked potential (DNSEP) is a scientific and objective technique that provides effective and objective data to establish the diagnosis of premature ejaculation (PE).

AIM

To explore differences in DNSEP between patients with primary premature ejaculation (PPE) and those with secondary premature ejaculation (SPE), in order to investigate the clinical value of DNSEP in the diagnosis of PE.

METHODS

The participants were divided into a PPE group (34 cases), an SPE group (25 cases) and a healthy control group (18 cases). All participants underwent DNSEP testing, and the latencies and amplitudes of DNSEP were recorded.

OUTCOMES

Differences in the latencies and amplitudes of DNSEP were compared among the PPE, SPE, and healthy control groups.

RESULTS

The latencies of DNSEP in the PPE and SPE groups were shorter than those in the healthy control group, and these differences were statistically significant (P < 0.01). However, there was no statistically significant difference between the PPE and SPE groups (P > 0.05). The amplitudes of DNSEP in the PPE group were significantly higher than those in the healthy control group (P < 0.01). However, the amplitudes of DNSEP in the SPE group were significantly lower than those in the healthy control group (P < 0.05).

CLINICAL IMPLICATIONS

PPE and SPE can be differentiated based on differences in the amplitudes of DNSEP, providing an objective basis for treatments and follow-up examinations.

STRENGTHS AND LIMITATIONS

We evaluated differences in the amplitudes of DNSEP between PPE and SPE patients, which were rare in the published literature. However, specific causes of these differences are still unclear. SEP only reflects afferent pathways in the ejaculatory reflex arc, and role of the brain as a higher center should not be ignored.

CONCLUSION

Both PPE and SPE patients are characterized by an increased excitability of the penile sensory nerves. Sun Z, Liao Z, Zheng Q, et al. A Study of Differences in Penile Dorsal Nerve Somatosensory Evoked Potential Testing Among Healthy Controls and Patients With Primary and Secondary Premature Ejaculation. J Sex Med Rev 2021;18:732-736.

Association of NE, leptin, and 5-HT with electrophysiological parameters in patients with primary premature ejaculation

OBJECTIVE

To investigate the possible role of serum norepinephrine (NE), leptin, and 5-hydroxytryptamine (5-HT) and their correlations with sympathetic skin response located in the penis (PSSR) in primary premature ejaculation (PPE).

METHODS

We compared the serum level of NE, leptin, and 5-HT, intravaginal ejaculatory latency time (IELT) and the premature ejaculation diagnostic tool (PEDT) scores between 57 PPE patients and 42 healthy control men as controls, who were recruited between September 2016 and January 2019. Additionally, the amplitude and latency of PSSR were measured and compared between the two groups.

RESULTS

Compared with healthy men, both leptin and NE increased significantly in PPE patients (P = .003, P = .005), while serum 5-HT remarkably decreased (P = .002). Serum leptin, NE, and 5-HT were significantly correlated with the diagnosis of PPE, PSSR amplitude, and latency. Moreover, compared with single serum indicator, NE/5-HT and leptin/5-HT had a stronger correlation with both PSSR amplitude (r = .8377, P < .001; r = .9323, P < .001, respectively) and latency (r = -.8058, P < .001; r = -.8901, P < .001, respectively).

CONCLUSION

Significant differences in leptin, NE, and 5-HT are observed between PPE patients and the controls, which supports the hypothesis of hyperactive sympathetic nerve system (SNS) in PPE. Additionally, leptin/5-HT ratio may serve as an ideal indicator for reflecting SNS activity and predicting treatment response in PPE patients in the future.

Anxiety and Performance in Sex, Sport, and Stage: Identifying Common Ground

Anxiety has long been associated with diminished performance within a number of domains involving evaluative interpersonal interactions, including Sex, Sport, and Stage. Here, we pose three questions: (1) how do these disparate fields approach and understand anxiety and performance; (2) how does the understanding of the issue within one field offer insight to another field; and (3) how could each field benefit from the ideas and strategies used by the others. We begin with a short review of models of anxiety/arousal and performance and then explore definitions, models, presumed underlying physiological processes, and characterizing and influencing factors within each domain separately in a narrative review. This discussion is followed by a synthesis that identifies elements specific to and common across the various domains, with the latter captured in a model of essential characteristics. Concluding remarks note the potential value of promoting increased cross-disciplinary conversation and research, with each domain likely benefiting from the conceptualizations and expert knowledge of the others.

Sympathetic skin response in patients with primary premature ejaculation

To evaluate the possible role of the autonomic (sympathetic) nervous system function among the patients with primary premature ejaculation (PPE) and determine whether there is an etiological basis for this condition. We performed sympathetic skin response located in the penis (PSSR) in 52 patients with PPE and 46 normally potent men. The latencies and amplitudes of PSSR were measured. The PSSR waveforms were classified into P type and N type according to the waveform characteristics. The waveform distribution in the PPE patients was not statistically different from that in the control group (P=0.609). Mean latency of the PSSR was significantly shorter in the patients than that in the normally potent men (P<0.001). Mean amplitude of the PSSR was significantly greater in patients than that in the normal men (P<0.001). Patients with PPE have hyperactivity of the sympathetic nervous system, which may be another factor involved in the pathological mechanisms of PPE, and the PSSR is an objective test to evaluate patients with PPE.