Voiding Dysfunction in Old Male Rats Associated With Enlarged Prostate and Irregular Afferent-Triggered Reflex Responses

Purpose: This study was conducted to evaluate the hypothesis that an enlarged prostate in old rats may lead to complications associated with voiding dysfunction involving ionotropic P2X2/3-type purinergic receptorsMethods: Intact animals were divided into male young (MYR; 8–10 weeks old) and male old (MOR; 20 months old) rats. The animals underwent simultaneous detrusor electromyography (EMG) and suprapubic cystometry (CMG) under urethane anesthesia. Immunofluorescence techniques were used to evaluate prostatic autonomic innervation and P2X3R expression in bladder urothelial cells. The functional role of P2X3R was characterized by intramuscular application of AF-353, a selective P2X2/3R antagonist.Results: The prostate index significantly increased in MOR, suggestive of an enlarged prostate affecting micturition patterns. Significant EMG and CMG differences were found between MYR and MOR. Higher immunoreactivity for P2X2/3R in the urothelial layer and for prostatic neurofilaments was seen in MOR. Systemic inhibition of P2X2/3R had minimal effects on MYR responsiveness, but improved voiding function in MOR with a marked decrease of intravesical pressure and bladder contractile responses.Conclusions: The data support the hypothesis that an enlarged prostate in MOR may contribute to voiding dysfunction involving activation of P2X2/3R, which enhances a prostate-bladder reflex. This reflex may increase bladder afferent transmission and activation of increased prostate innervation, leading to voiding dysfunction.

Autonomic innervation of the carotid body as a determinant of its sensitivity: implications for cardiovascular physiology and pathology

The motivation for this review comes from the emerging complexity of the autonomic innervation of the carotid body (CB) and its putative role in regulating chemoreceptor sensitivity. With the carotid bodies as a potential therapeutic target for numerous cardiorespiratory and metabolic diseases, an understanding of the neural control of its circulation is most relevant. Since nerve fibres track blood vessels and receive autonomic innervation, we initiate our review by describing the origins of arterial feed to the CB and its unique vascular architecture and blood flow. Arterial feed(s) vary amongst species and, unequivocally, the arterial blood supply is relatively high to this organ. The vasculature appears to form separate circuits inside the CB with one having arterial venous anastomoses. Both sympathetic and parasympathetic nerves are present with postganglionic neurons located within the CB or close to it in the form of paraganglia. Their role in arterial vascular resistance control is described as is how CB blood flow relates to carotid sinus afferent activity. We discuss non-vascular targets of autonomic nerves, their possible role in controlling glomus cell activity, and how certain transmitters may relate to function. We propose that the autonomic nerves sub-serving the CB provide a rapid mechanism to tune the gain of peripheral chemoreflex sensitivity based on alterations in blood flow and oxygen delivery, and might provide future therapeutic targets. However, there remain a number of unknowns regarding these mechanisms that require further research that is discussed.

The autonomic innervation of hairy skin in humans: an in vivo confocal study

The autonomic innervation of the skin includes different subsets of adrenergic and cholinergic fibers both in humans and animals. The corresponding chemical code is complex and often difficult to ascertain. Accordingly, a detailed histochemical description of skin autonomic fiber subtypes is lacking in humans. To characterize skin autonomic nerve subtypes may help to better understand the selective damage of specific skin autonomic fibers affecting human diseases such as the adrenergic fibers directed to skin vessels in Parkinson’s disease or the cholinergic sudomotor fibers in Ross Syndrome. The present study aimed at characterizing subtypes of autonomic fibers in relation to their target organs by means of an immunofluorescent technique and confocal microscopy. We studied 8 healthy subjects (5 males and 3 females) aged 45 ± 2 (mean ± SE) years without predisposing causes for peripheral neuropathy or autonomic disorders. They underwent skin biopsy from proximal (thigh) and distal (leg) hairy skin. A combination of adrenergic (i.e. tyrosine-hydroxylase- TH and dopamine beta-hydroxylase- DbH) and cholinergic (vesicular acetylcholine transporter- VACHT) autonomic markers and neuropeptidergic (i.e. neuropeptide Y- NPY, calcitonin gene-related peptide- CGRP, substance P- SP, and vasoactive intestinal peptide- VIP) markers were used to characterize skin autonomic fibers. The analysed skin autonomic structures included: 58 sweat glands, 91 skin arterioles and 47 arrector pili muscles. Our results showed that all skin structures presented a sympathetic adrenergic but also cholinergic innervation although in different proportions. Sympathetic adrenergic fibers were particularly abundant around arterioles and arrector pili muscles whereas sympathetic cholinergic fibers were mainly found around sweat glands. Neuropeptides were differently expressed in sympathetic fibers: NPY were found in sympathetic adrenergic fibers around skin arterioles and very seldom sweat glands but not in adrenergic fibers of arrector pili muscles. By contrast CGRP, SP and VIP were expressed in sympathetic cholinergic fibers. Cholinergic fibers expressing CGRP, SP or VIP without TH or DbH staining were found in arterioles and arrector pili muscles and they likely represent parasympathetic fibers. In addition, all skin structures contained a small subset of neuropeptidergic fibers devoid of adrenergic and cholinergic markers with a likely sensory function. No major differences were found between males and females and proximal and distal sites. In summary hairy skin contains sympathetic adrenergic and cholinergic fibers differently distributed around skin structures with a specific distribution of neuropeptides. The autonomic skin innervation also contains a small amount of fibers, likely to be parasympathetic and sensory.

P5392Epicardium derived cells promote sympathetic ganglionic outgrowth towards myocardium in vitro

Background The autonomic nerve system is essential to maintain homeostasis in the body. In the heart, autonomic innervation is important for adjusting the physiology to the continuously changing demands such as stress responses. After cardiac damage, excessive neurite outgrowth, referred to as autonomic hyperinnervation, can occur which is related to ventricular arrhythmias and sudden cardiac death. The cellular basis for this hyperinnervation is as yet unresolved. Here we hypothesize a role for epicardium derived cells (EPDCs) in stimulating sympathetic neurite outgrowth. Purpose To investigate the potential role of adult EPDCs in promoting sympathetic ganglionic outgrowth towards adult myocardium. Method Fetal murine superior cervical ganglia were dissected and co-cultured with activated adult mesenchymal epicardium-derived cells (EPDCs) or/and adult myocardium in a 3D collagen gel culture system. Four experiment groups were included: Group 1: Vehicle cultures (ganglia cultured without EPDC/myocardium) (n=48); Group 2: ganglia co-cultured with EPDCs (n=38); Group 3: ganglia co-cultured with myocardium (n=95); and group 4: ganglia co-cultured with both EPDCs and myocardium (n=96). The occurrence of neurite outgrowth was assessed in each group. The density of neurites that showed directional sprouting (i.e. sprouting towards myocardium) was assessed as well with a semi-automatic quantification method. Finally, sub-analyses were made by taking gender into account. Results Cervical ganglia cultured with EPDCs alone (group 2) showed increased neurite outgrowth compared to vehicle cultures (group 1), however the neurites did not show directional sprouting towards EPDCs. When co-cultured with myocardium (group 3), directional neurite outgrowth towards myocardium was observed. Compared to the ganglia-myocardium co-cultures, directional outgrowth was significantly increased in co-cultures combining myocardium and EPDCs (group 4), and the neurite density was also significantly augmented. Comparison between males and female ganglia demonstrated that more neurite outgrowth occurred in female-derived ganglia than in male-derived ganglia under the same co-culture conditions. Conclusion Activated adult EPDCs promote sympathetic ganglionic outgrowth in vitro. Sex differences exist in the response of ganglia to EPDCs, and female-derived ganglia appear more sensitive to EPDC-signalling. Results support a role of EPDCs in cardiac autonomic innervation and open avenues for exploring of their role in ventricular hyperinnervation after cardiac damage.