Erectile Dysfunction
Botros Rizk, Ashok Agarwal, Edmund S. Sabanegh in Male Infertility in Reproductive Medicine, 2019
The penile erection occurs as a neurovascular cascade that is closely influenced by hormonal and psychological factors. In the flaccid or resting state, the tone of cavernosal smooth muscle is increased resulting in a high peripheral vascular resistance. This results in a small volume of blood entering the corporal bodies (Figure 12.1). This is controlled by the sympathetic nervous system and the neurotransmitter noradrenaline. Sexual stimulation and subsequent neuronal activation results in vasodilation and relaxation of cavernosal smooth muscle. Several neurotransmitters are involved in eliciting an erection; however, nitric oxide (NO) appears to play a key role. NO is released from the parasympathetic and nonadrenergic noncholinergic (NANC) neurons in the cavernosal smooth muscle [5].
ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
The function of sleep remains speculative. The function of non-REM sleep is thought to be the restoration of bodily functions. In support of this notion, non-REM sleep represents the largest portion of sleep time, and is associated with decreases in autonomic functioning such as heart rate, blood pressure and rate of respiration, as well as increased release of GROWTH HORMONE, PROLACTIN and Other hormones. In contrast, much less is known about the function of REM sleep. Unlike non-REM sleep, REM sleep is associated with elevated AUTONOMIC activity, although temperature regulation is lost. Penile erection occurs in males. Subjects awakened during REM sleep often report dreaming. These observations suggest that the brain is active during REM sleep. One hypothesis is that REM sleep helps to maintain the excitability of the cerebral cortex. This might have a role in the CONSOLIDATION of MEMORY in adults, and in stimulating the developing brain, as new-born babies sleep about 16 hours a day about half of which is spent in REM sleep. This cortical HOMEOSTASIS hypothesis is consistent with the view that REM sleep represents evolutionarily a more recent phenomenon than non-REM sleep because it is seen only in mammalian species.
Case 47: I’m impotent
Barry Wright, Subodh Dave, Nisha Dogra in 100 Cases in Psychiatry, 2017
Erectile dysfunction can be caused by cardiovascular problems (e.g. vascular disease in diabetes) reducing blood flow to the area, but the fact that this man can sustain an erection at other times, and the normal cardiovascular examination, make this unlikely. There is no evidence that he has low testosterone. Visual field defects are absent and there is no evidence of raised intracranial pressure or brain pathology. Smoking and alcohol consumption can affect sexual function. This is not obviously present but it will be worth asking more questions about potential illicit drug use or use of any other medications (neuroleptics and antihypertensives would be the usual culprits). Nervous system disorders that affect sexual function tend to be those affecting older people such as Parkinson’s disease, cerebrovascular accident or multiple sclerosis, although trauma to the spine may also affect function. All of these are ruled out here by history and examination. Some local cancers or local disease (e.g. Peyronie disease) can be ruled out by normal appearance and the absence of pain or other symptoms. Aggressive cancer treatment or treatments for some systemic diseases can also affect erectile function.
Potential mechanism of Achyranthis bidentatae radix plus semen vaccariae granules in the treatment of diabetes mellitus-induced erectile dysfunction in rats utilizing combined experimental model and network pharmacology
Published in Pharmaceutical Biology, 2021
Ji-Sheng Wang, Jun-Long Feng, Heng-Heng Dai, Zi-Long Chen, Xiao Li, Bing-Hao Bao, Sheng Deng, Fan-Chao Meng, Qi Zhao, Hong-Sheng Xu, Bin Wang, Hai-Song Li
DMED has become a research “hotspot” in recent years (Qiu et al. 2021). Penile erection is caused first by the body accepting conduction of a nerve impulse, which leads to relaxation of smooth muscle in the cavernous tissue of the penis, inflow of arterial blood, occlusion of venous vessels, increased blood volume in the penis, and then erection (Thorve et al. 2011). Any factors leading to decreased blood flow to the penis can lead to ED. Hyperglycaemia in DM patients can produce peripheral vascular lesions by affecting vascular walls and endothelial factors. These actions lead to the glycosylation of elastic fibres in vascular walls, which limits vasodilation in cavernous sinusoids, reduces blood flow in the cavernous body and, thus, affects penile erection (Richards and Vinik 2002; De Young et al. 2004). DMED pathogenesis may also be related to oxidative-stress injury caused by a long-term hyperglycaemic environment in DM patients. The products of oxidative stress (e.g., reactive oxygen species, malondialdehyde, 8-oxo-2′-deoxyguanosine) damage vascular endothelial cells (VECs), affect the release of nitric oxide (NO) and other factors released by endothelial cells, and can even cause VEC apoptosis (Cui et al. 2018).
Therapeutic potential of Mucuna pruriens (Linn.) on ageing induced damage in dorsal nerve of the penis and its implication on erectile function: an experimental study using albino rats
Published in The Aging Male, 2020
Prakash Seppan, Ibrahim Muhammed, Karthik Ganesh Mohanraj, Ganesh Lakshmanan, Dinesh Premavathy, Sakthi Jothi Muthu, Khayinmi Wungmarong Shimray, Sathya Bharathy Sathyanathan
Penile erection is a complex neurovascular phenomenon. It involves not only the coordination of three hemodynamic events (increased arterial flow, sinusoidal smooth muscle relaxation, and decreased venous drainage) but also the interaction of the brain, nerves, neurotransmitters, smooth and striated muscle, and the tunica albuginea. An alteration in any of these components may decrease the response of the erectile tissue and cause dysfunction [6]. Mechanisms involving vasculogenic and neurogenic factors along with reduced serum testosterone are involved in ED associated with aging [7,8]. Although the molecular mechanisms underlying neurogenic ED are not well understood, the principal theories include impairment in neuronal nitric oxide synthase (nNOS) function and nitric oxide (NO) bioavailability, reduced blood supply to nerve tissue, deficiency of neurohormonal growth factors, and increased oxidative stress [9]. The dorsal nerve of the penis (DNP) is being one of the major sources of nNOS, its integrity is of utmost importance to maintain an erection. Unfortunately, it is often overlooked in the current scenario. The present study focused on the alterations of dorsal nerve of the penis and erectile function in aging male subject and analyzing the therapeutic potential of Mucuna pruriens (M. pruriens) towards controlling the damage to DNP.
Evaluation of the effects of chronic stress applied from the prepubertal to the adult stages or only during adulthood on penile morphology in rats
Published in Stress, 2019
Carina Teixeira Ribeiro, Waldemar Silva Costa, Francisco José Barcellos Sampaio, Marco Aurélio Pereira Sampaio, Diogo Benchimol de Souza
Penile erection involves various complex neuroendocrine, vascular, and structural mechanisms. Basically, an erection occurs by distension of the cavernosal sinusoidal smooth muscle, followed by a subsequent increase in arterial blood flow and venous occlusion (van Driel, 2015). Therefore, impairment of any of these factors can result in erectile dysfunction. Chronic stress in rats has been reported to reduce levels of testosterone (de Souza et al., 2012), a hormone that plays an important role in the modulation and maintenance of penile structures, as well as in the neuroendocrine and vascular mechanisms that maintain erectile function (Traish, 2009). Structural changes, such as smooth muscle reduction, increased fibrosis, and endothelial and nerve dysfunction in the penile corpus cavernosum, were associated with suppression of testosterone levels in men and laboratory animals (Miranda, Gallo, De Souza, Costa, & Sampaio, 2012; Wang et al., 2015; Blick, Ritchie, & Sullivan, 2016). These changes were found to be correlated with erectile dysfunction (Costa, Carrerete, Horta, & Sampaio, 2006; Bal et al., 2009; van Driel, 2015).
Related Knowledge Centers
- Autonomic Nervous System
- Libido
- Physiology
- Nitric Oxide
- Vasodilation
- Parasympathetic Nervous System
- Penis
- Sexual Arousal
- Sexual Attraction
- Sexual Intercourse