The Acute Effects and Mechanism of Ketamine on Nicotine-Induced Neurogenic Relaxation of the Corpus Cavernosum in Mice.

The present study aimed to investigate the acute effects and the mechanism of ketamine on nicotine-induced relaxation of the corpus cavernosum (CC) in mice. This study measured the intra-cavernosal pressure (ICP) of male C57BL/6 mice and the CC muscle activities using an organ bath wire myograph. Various drugs were used to investigate the mechanism of ketamine on nicotine-induced relaxation. Direct ketamine injection into the major pelvic ganglion (MPG) inhibited MPG-induced increases in ICP. D-serine/L-glutamate-induced relaxation of the CC was inhibited by MK-801 (N-methyl-D-aspartate (NMDA) receptor inhibitor), and nicotine-induced relaxation was enhanced by D-serine/L-glutamate. NMDA had no effect on CC relaxation. Nicotine-induced relaxation of the CC was suppressed by mecamylamine (a non-selective nicotinic acetylcholine receptor antagonist), lidocaine, guanethidine (an adrenergic neuronal blocker), Nw-nitro-L-arginine (a non-selective nitric oxide synthase inhibitor), MK-801, and ketamine. This relaxation was almost completely inhibited in CC strips pretreated with 6-hydroxydopamine (a neurotoxic synthetic organic compound). Ketamine inhibited cavernosal nerve neurotransmission via direct action on the ganglion and impaired nicotine-induced CC relaxation. The relaxation of the CC was dependent on the interaction of the sympathetic and parasympathetic nerves, which may be mediated by the NMDA receptor.

Effect of ß3-adrenoceptor agonist on the micromotion of bilateral major pelvic ganglion-excised rat bladder.

AIMS: Micromotion is an autonomous intramural movement of the bladder, and is believed to be an initial step in the generation of urinary urgency. Therefore, controlling micromotion may be a novel target in overactive bladder (OAB) treatment. However, developing micromotion treatment has been limited by the absence of a standardized animal model. We attempted to create a micromotion animal model and investigated the effectiveness of a ß3 -adrenoceptor agonist (CL316,243) on micromotion. METHODS: Bilateral major pelvic ganglia (MPGs) were excised in 18 male Sprague-Dawley rats, resulting in an almost completely denervated bladder. On postoperative Day 7, cystometry was performed. Rats were divided into three treatment groups: CL316,243; ß3- adrenoceptor antagonist (SR59230A) pretreated CL316,243; and a nonselective antimuscarinic agent (oxybutynin). Changes in micromotion were evaluated after the intra-arterial administration of each agent. RESULTS: Low-amplitude oscillations in intravesical pressure (micromotion) were observed 1 week after MPGs excision. Micromotion frequency significantly (p = 0.003) decreased (2.17 ± 3.54 times/5 min) with CL316,243 compared with vehicle (6.33 ± 1.97 times/5 min). Micromotion amplitude also decreased with CL316,243 (1.15 ± 1.93 cmH2 O) compared with vehicle (5.96 ± 5.12 cmH2 O), approaching conventional significance (p = 0.090). No significant decreases in frequency or amplitude were observed with oxybutynin treatment. CONCLUSIONS: Systemic administration of the ß3 -adrenoceptor agonist CL316,243 effectively controlled micromotion in bilateral MPGs-excised, almost completely denervated rat bladders. This result indicates that ß3 -adrenoceptor agonist may affect the bladder directly, suggesting that it might be effective for overall OAB, regardless of the presence or level of neurological deficits. Bilateral MPGs-excised rats are considered a plausible micromotion animal model suitable for future research.

Mapping afferent and pelvic postganglionic neurons of the urethra from female rats: The L6 DRG is the major primary afferent supplier.

AIMS: To map sensory and pelvic postganglionic neurons from three different regions of the female rat urethra. METHODS: The neuronal tracer True Blue (TB) was injected into the pre-pelvic, pelvic, and clitoral regions of the urethra from female Wistar rats. Seven days after TB injection, TB+ cells from the dorsal root ganglia (DRGs) and the major pelvic ganglion (MPG) were examined. The number and morphometry of TB+ cells were determined. RESULTS: TB+ cells were mainly distributed in lumbar 1 (L1), lumbar 2 (L2), lumbar 6 (L6), and sacral 1 (S1) DRGs, and in the MPG. The mean number of sensory neurons was 1200 ± 143. TB injection in pre-pelvic and pelvic urethra labeled neurons in L1, L2, L6, and S1 DRGs. TB injection in clitoral urethra labeled neurons in L6 and S1 DRGs. L6 DRG contained >50% of the total urethral TB+ neurons, and ~80% of the clitoral region. The mean value of the total number of MPG TB+ neurons was 1217 ± 72. DRG and MPG neurons projecting to the urethra presented a somatotopic distribution. CONCLUSIONS: The results demonstrated that L6 DRG is the major supplier of afferent innervation to the urethra, and that the distal urethral region is exclusively innervated by lower lumbosacral DRGs. Considering that electrical stimulation of sensory pudendal nerve improves overactive bladder, and that most of the sensory neurons in the distal urethra are from L6 DRG, electrical stimulation of this ganglion may be an innovative and effective neuromodulation therapy for neurogenic urinary dysfunctions.

Spatiotemporal mapping of sensory and motor innervation of the embryonic and postnatal mouse urinary bladder.

The primary function of the urinary bladder is to store urine (continence) until a suitable time for voiding (micturition). These distinct processes are determined by the coordinated activation of sensory and motor components of the nervous system, which matures to enable voluntary control at the time of weaning. Our aim was to define the development and maturation of the nerve-organ interface of the mouse urinary bladder by mapping the organ and tissue distribution of major classes of autonomic (motor) and sensory axons. Innervation of the bladder was evident from E13 and progressed dorsoventrally. Increasing defasciculation of axon bundles to single axons within the muscle occurred through the prenatal period, and in several classes of axons underwent further maturation until P7. Urothelial innervation occurred more slowly than muscle innervation and showed a clear regional difference, from E18 the bladder neck having the highest density of urothelial nerves. These features of innervation were similar in males and females but varied in timing and tissue density between different axon classes. We also analysed the pelvic ganglion, the major source of motor axons that innervate the lower urinary tract and other pelvic organs. Cholinergic, nitrergic (subset of cholinergic) and noradrenergic neuronal cell bodies were present prior to visualization of these axon classes within the bladder. Examination of cholinergic structures within the pelvic ganglion indicated that connections from spinal preganglionic neurons to pelvic ganglion neurons were already present by E12, a time at which these autonomic ganglion neurons had not yet innervated the bladder. These putative preganglionic inputs increased in density prior to birth as axon terminal fields continued to expand within the bladder tissues. Our studies also revealed in numerous pelvic ganglion neurons an unexpected transient expression of calcitonin gene-related peptide, a peptide commonly used to visualise the peptidergic class of visceral sensory axons. Together, our outcomes enhance our understanding of neural regulatory elements in the lower urinary tract during development and provide a foundation for studies of plasticity and regenerative capacity in the adult system.

Impairment of accessory nerves around major pelvic ganglion leading to overflow urinary incontinence in rats.

AIMS: To investigate the relationship between lower urinary tract function and the accessory nerve (ACN) arising from the major pelvic ganglion (MPG). METHODS: Ten-week-old male Wistar/ST rats were randomly divided into eight groups according to the type of treatment (sham or bilateral accessory nerve injury [BACNI]) and the duration of observation (3 days, 1 week, 2 weeks, or 4 weeks: Sham-3d, Sham-1w, Sham-2w, Sham-4w, BACNI-3d, BACNI-1w, BACNI-2ws, and BACNI-4w. BACNI was induced in the following manner: the ACN was crushed for 1 min (2 mm away from the MPG) using reverse-action tweezers. The same procedure was performed on both sides. On the last day of each observation period, the bladder function was measured by awake cystometry, and histological evaluation was performed. RESULTS: All rats in the Sham groups micturated normally. In the BACNI-3d and BACNI-1w groups, all rats showed symptoms of overflow urinary incontinence (OUI). This OUI improved gradually over time. The bladder's size in the BACNI group was significantly larger than that in the Sham group (p < .01). In addition, fibrosis was observed in the subserosa of the bladder of rats in BACNI groups. CONCLUSION: The BACNI model rats exhibited OUI, suggesting that ACN is involved in the lower urinary tract function. It might be possible that ACN controls the function of either the bladder, the urethra, or both.

Exosome Released From Schwann Cells May Be Involved in Microenergy Acoustic Pulse-Associated Cavernous Nerve Regeneration.

BACKGROUND: Neurogenic erectile dysfunction (ED) is often refractory to treatment because of insufficient functional nerve recovery after injury or insult. Noninvasive mechano-biological intervention, such as microenergy acoustic pulse (MAP), low-intensity pulsed ultrasound, and low-intensity extracorporeal shockwave treatment, is an optimal approach to stimulate nerve regeneration. AIM: To establish a new model in vitro to simulate nerve injury in neurogenic ED and to explore the mechanisms of MAP in vitro. METHODS: Sprague-Dawley rats were used to isolate Schwann cells (SCs), major pelvic ganglion (MPG), and cavernous nerve with MPG (CN/MPG). SCs were then treated with MAP (0.033 mJ/mm2, 1 Hz, 100 pulses), and SC exosomes were isolated. The MPG and CN/MPG were treated with MAP (0.033 mJ/mm2, 1 Hz) at different dosages (25, 50, 100, 200, or 300 pulses) or exosomes derived from MAP-treated SCs in vitro. OUTCOMES: Neurite growth from the MPG fragments and CN was photographed and measured. Expression of neurotropic factors (brain-derived neurotrophic factor, nerve growth factor, and neurotrophin-3) was checked. RESULTS: Neurite outgrowth from MPG and CN/MPG was enhanced by MAP in a dosage response manner, peaking at 100 pulses. MAP promoted SC proliferation, neurotropic factor (brain-derived neurotrophic factor, nerve growth factor, and neurotrophin-3) expression, and exosome secretion. SC-derived exosomes significantly enhanced neurite outgrowth from MPG in vitro. CLINICAL IMPLICATIONS: MAP may have utility in the treatment of neurogenic ED by SC-derived exosomes. STRENGTH & LIMITATIONS: We confirmed that MAP enhances penile nerve regeneration through exsomes. Limitations of this study include that our study did not explore the exact mechanisms of how MAP increases SC exosome secretion nor whether MAP modulates the content of exosomes. CONCLUSION: This study revealed that neurite outgrowth from MPG was enhanced by MAP and by SC-derived exosomes which were isolated after MAP treatment. Our findings indicate that one mechanism by which MAP induces nerve regeneration is by stimulation of SCs to secrete exosomes. Peng D, Reed-Maldonado AB, Zhou F, et al. Exosome Released From Schwann Cells May Be Involved in Microenergy Acoustic Pulse-Associated Cavernous Nerve Regeneration. J Sex Med 2020;17:1618-1628.

Neural interrelationships of autonomic ganglia from the pelvic region of male rats.

The aims of the present study were to describe, in male rats, the anatomical organization of the major and accessory pelvic ganglia (MPG, AG; respectively), the interrelationship of the pelvic plexus components, and the morphometry of the pelvic postganglionic neurons. Anatomical, histochemical and histological studies were performed in anesthetized adult Wistar male rats. We found that the pelvic plexus consists of intricate neural circuits composed of two MPG, and three pairs of AG (AGI, AGII, AGIII) anatomically interrelated through ipsilateral and contralateral commissural nerves. Around 30 nerves emerge from each MPG and 17 from AGI and AGII. The MPG efferent nerves spread out preganglionic information to several pelvic organs controlling urinary, bowel, reproductive and sexual functions, while AG innervation is more regional, and it is confined to reproductive organs located in the rostral region of the urogenital tract. Both MPG and AG contain nerve fascicles, blood vessels, small intensely fluorescent cells, satellite cells and oval neuronal somata with one to three nucleoli. The soma area of AG neurons is larger than those of MPG neurons (p < 0.005). The MPG contains about 75% of the total pelvic postganglionic neurons. Our findings corroborated previous reports about MPG inputs, and add new information regarding pelvic ganglia efferent branches, AG neurons (number and morphometry), and neural interrelationship between the pelvic plexus components. This information will be useful in designing future studies about the role of pelvic innervation in the physiology and pathophysiology of pelvic functions.

Reinnervation of the rectum with transfer of the genital branch of the genitofemoral nerve to the pelvic nerve in rats.

OBJECTIVE The purpose of this study was to determine the feasibility of rectum reinnervation with transfer of a primarily genitofemoral nerve to the pelvic nerve in the rat. METHODS Thirty-six male rats were randomly divided into 3 groups: rats in the nerve transfer group (n = 12) were subjected to rectal denervation and then bilateral genitofemoral nerve-pelvic nerve transfer; rats in the nerve resection group (n = 12) underwent rectum denervation without nerve transfer; and rats in the control group (n = 12) underwent sham surgery. Rectum denervation was achieved by transection of the L-6 spinal nerves, the spinal nerves below L-6, and the pelvic nerve. Four months postoperatively, retrograde nerve tracing, regenerative nerve morphological examination, and rectal manometry assessment were performed. RESULTS Regenerative nerve morphological examination showed good axonal regeneration after genitofemoral nerve transfer. Nerve stimulation induced increased rectal pressures in 10 of 12 rats in the nerve transfer group. The mean rectal pressure in this group was 54.9 ± 7.1 mm Hg, which is higher than the mean value in the nerve resection group (5.5 ± 2.0 mm Hg) but lower than that in the control group (70.6 ± 8.5 mm Hg) (p < 0.05). The appearance of FluoroGold-labeled neurons in the L-1 and L-2 spinal cord segments in the nerve transfer group confirmed the formation of new neural pathways. CONCLUSIONS The results have demonstrated that genitofemoral nerve-pelvic nerve transfer can achieve nerve regeneration. In this animal model, the authors were able to reinnervate the rectum by nerve transfer.

M1 Macrophages Are Predominantly Recruited to the Major Pelvic Ganglion of the Rat Following Cavernous Nerve Injury.

INTRODUCTION: Neurogenic erectile dysfunction is a common sequela of radical prostatectomy. The etiology involves injury to the autonomic cavernous nerves, which arise from the major pelvic ganglion (MPG), and subsequent neuroinflammation, which leads to recruitment of macrophages to the injury site. Currently, two macrophage phenotypes are known: neurotoxic M1 macrophages and neuroprotective M2 macrophages. AIM: To examine whether bilateral cavernous nerve injury (BCNI) in a rat model of erectile dysfunction would increase recruitment of neurotoxic M1 macrophages to the MPG. METHODS: Male Sprague-Dawley rats underwent BCNI and the MPG was harvested at various time points after injury. The corpora cavernosa was used to evaluate tissue myographic responses to electrical field stimulation ex vivo. Quantitative real-time polymerase chain reaction was used to examine the gene expression of global macrophage markers, M1 macrophage markers, M2 macrophage markers, and cytokines and chemokines in the MPG. Mathematical calculation of the M1/M2 index was used to quantify macrophage changes temporally. Western blot of MPG tissues was used to evaluate the protein amount of M1 and M2 macrophage markers quantitatively. Immunohistochemistry staining of MPGs for CD68, CD86, and CD206 was used to characterize M1 and M2 macrophage infiltration. MAIN OUTCOME MEASURES: Corpora cavernosa responsiveness ex vivo; gene (quantitative real-time polymerase chain reaction) and protein (western blot) expressions of M1 and M2 markers, cytokines, and chemokines; and immunohistochemical localization of M1 and M2 macrophages. RESULTS: BCNI impaired the corporal parasympathetic-mediated relaxation response to electrical field stimulation and enhanced the contraction response to electrical field stimulation. Gene expression of proinflammatory (Il1b, Il16, Tnfa, Tgfb, Ccl2, Ccr2) and anti-inflammatory (Il10) cytokines was upregulated in the MPG 48 hours after injury. M1 markers (CD86, inducible nitric oxide synthase, interleukin-1ß) and M2 markers (CD206, arginase-1, interleukin-10) were increased after BCNI in the MPG, with the M1/M2 index above 1.0 indicating that more M1 than M2 macrophages were recruited to the MPG. Protein expression of the M1 macrophage marker (inducible nitric oxide synthase) was increased in MPGs after BCNI. However, the protein amount of M2 macrophage markers (arginase-1) remained unchanged. Immunohistochemical characterization demonstrated predominant increases in M1 (CD68+CD86+) macrophages in the MPG after BCNI. CONCLUSION: These results suggest that an increase in M1 macrophage infiltration of the MPG after BCNI is associated with impaired neurogenically mediated erectile tissue physiology ex vivo and thus has significant implications for cavernous nerve axonal repair. Future studies are needed to demonstrate that inhibition of M1 macrophage recruitment prevents erectile dysfunction after CNI.

Neuroanatomic and behavioral correlates of urinary dysfunction induced by vaginal distension in rats.

The aim of the present study was to use a model of simulated human childbirth in rats to determine the damage to genitourinary structures and behavioral signs of urinary dysfunction induced by vaginal distension (VD) in female rats. In experiment 1, the length of the genitourinary tract and the nerves associated with it were measured immediately after simulated human delivery induced by VD or sham (SH) procedures. Electroneurograms of the dorsal nerve of the clitoris (DNC) were also recorded. In experiment 2, histological characteristics of the bladder and major pelvic ganglion of VD and SH rats were evaluated. In experiment 3, urinary parameters were determined in conscious animals during 6 h of dark and 6 h of light before and 3 days after VD or SH procedures. VD significantly increased distal vagina width (P < 0.001) and the length of the motor branch of the sacral plexus (P < 0.05), DNC (P < 0.05), and vesical nerves (P < 0.01) and decreased DNC frequency and amplitude of firing. VD occluded the pelvic urethra, inducing urinary retention, hematomas in the bladder, and thinness of the epithelial (P < 0.05) and detrusor (P < 0.01) layers of the bladder. Major pelvic ganglion parameters were not modified after VD. Rats dripped urine in unusual places to void, without the stereotyped behavior of micturition after VD. The neuroanatomic injuries after VD occur alongside behavioral signs of urinary incontinence as determined by a new behavioral tool for assessing micturition in conscious animals.

Neuregulin 1 as an endogenous regulator of nicotinic acetylcholine receptors in adult major pelvic ganglion neurons.

We investigated whether endogenous neuregulin 1 (NRG1) is released in a soluble form (called sNRG1) and upregulates expression of nicotinic acetylcholine receptor (nAChR) in autonomic major pelvic ganglion (MPG) neurons of adult rats. To elicit the release of sNRG1, either the hypogastric nerve or the pelvic nerve was electrically stimulated. Then, the MPG-conditioned medium (CM) was subjected to western blotting using an antibody directed against the N-terminal ectodomain of NRG1. Both sympathetic and parasympathetic nerve activation elicited the release of sNRG1 from MPG neurons in a frequency-dependent manner. The sNRG1 release was also induced by treatment of MPG neurons with either high KCl or neurotrophic factors. The biological activity of the released sNRG1 was detected by tyrosine phosphorylation (p185) of the ErbB2 receptors in MPG neurons. When MPG neurons were incubated for 6 h in the CM, the protein level of the nAChR α3 subunit and ACh-induced current (IACh) density were significantly increased. The CM-induced changes in IACh was abolished by a selective ErbB2 tyrosine kinase inhibitor. Taken together, these data suggest that NRG1 functions as an endogenous regulator of nAChR expression in adult MPG neurons.

Increased expression of the neuroregenerative peptide galanin in the major pelvic ganglion following cavernous nerve injury.

INTRODUCTION: Erectile dysfunction (ED) remains a frequent complication of radical prostatectomy due to injury to the cavernous nerves (CNs). A recent microarray showed the neuropeptide galanin to be one of the most strikingly upregulated genes in the rat major pelvic ganglion (MPG) after bilateral CN crush injury (BCNI). AIM: The aim of this study is to evaluate the temporal regulation of galanin in the MPG after BCNI and its relationship to functional nerve regeneration. METHODS: Changes in galanin, galanin receptor (galR), and c-JUN mRNA expression were assessed in Sprague-Dawley rats after sham operation (n = 10) and at 48 hours (n = 10), 7 (n = 10), 14 (n = 5), 21 (n = 5), 30 (n = 5), and 60 (n = 5) days after BCNI using quantitative PCR. Erectile function was assessed by measuring intracavernous pressure (ICP) divided by mean arterial pressure (MAP) during CN electrostimulation. Immunohistochemistry was performed on the MPG in sham-operated animals and 5 days after BCNI. MAIN OUTCOME MEASURES: ICP/MAP upon CN stimulation; galanin, galR1, -2, -3, and c-JUN mRNA expression at various time points after BCNI; and nNOS, galanin, and galR distribution in the MPG of sham-operated rats and after BCNI. RESULTS: After BCNI, ICP/MAP values quickly deteriorate, while after 60 days, spontaneous restoration of erectile responses to CN stimulation is observed, reflecting CN regeneration. Galanin mRNA in the MPG is up to 186-fold upregulated compared with sham-operated rats at 48 hours and 7 days after BCNI and gradually declines with increasing time from injury, whereas galanin receptor expressions decrease and c-JUN gradually increases. Galanin expression shows a strong inverse correlation with erectile responses to CN stimulation with time from injury. Injured MPGs show a colocalization between galanin- and nNOS-positive neuronal cell population in the MPG. CONCLUSIONS: Galanin is upregulated in the MPG in the early phase after CN injury after which it gradually decreases and is present in nNOS-positive neurons of the ganglion. We hypothesize that galanin upregulation is an important factor in the endogenous neuroregenerative response to CN injury.

Excitatory GABAA receptor in autonomic pelvic ganglion neurons innervating bladder.

Major pelvic ganglia (MPG) are relay centers for autonomic reflexes such as micturition and penile erection. MPG innervate the urogenital system, including bladder. γ-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mammalian central nervous system, and may also play an important role in some peripheral autonomic ganglia, including MPG. However, the electrophysiological properties and function of GABAA receptor in MPG neurons innervating bladder remain unknown. This study examined the electrophysiological properties and functional roles of GABAA receptors in bladder-innervating neurons identified by retrograde Dil tracing. Neurons innervating bladder showed previously established parasympathetic properties, including small membrane capacitance, lack of T-type Ca(2+) channel expression, and tyrosine-hydroxylase immunoreactivity. GABAA receptors were functionally expressed in bladder innervating neurons, but GABAC receptors were not. GABA elicited strong depolarization followed by increase of intracellular Ca(2+) in neurons innervating bladder, supporting the hypothesis GABA may play an important role in bladder function. These results provide useful information about the autonomic function of bladder in physiological and pathological conditions.

Stem-cell therapy for erectile dysfunction.

INTRODUCTION: Erectile dysfunction (ED) is the most common sexual disorder that men report to healthcare providers, and is the male sexual dysfunction that has been most investigated. Current treatments for ED focus on relieving the symptoms of ED and therefore tend to provide a temporary solution rather than a cure or reversing the cause. Recently, therapies based on stem cells (SCs) have had an increasing attention for their potential to restore erectile function. Preclinical studies showed that these cells might reverse the pathophysiological changes leading to ED, rather than treating the symptoms of ED. This review is intended to provide an overview of contemporary reports on the use of SCs to treat ED. METHODS: We made an extensive search for reports on SC-based therapy for the management of ED, published in English between 1966 and 2013, using the search engines SciVerse-sciencedirect, SciVerse-scopus, Google Scholar and Pubmed, with the search terms 'erectile dysfunction', 'stem cells', 'multipotent stromal cells', 'adipose (tissue) derived stem cells', 'bone-marrow derived stem cells', 'animal model', 'diabetes', 'ageing', 'Peyronie's Disease' and 'cavernous nerve injury'. RESULTS: Fifty-four papers were identified and contributed, either as an original research report or review thereof, to this review. Several preclinical studies addressed SC-based therapies for the recovery of erectile function caused by a variety of both chronic and acute conditions. Overall, these studies showed beneficial effects of SC therapy, while evidence on the mechanisms of action of SC therapy varied between studies. One clinical trial investigated the short-term effects of SC therapy in diabetic patients with ED. Two more clinical trials are currently recruiting patients. CONCLUSIONS: The rapidly expanding and highly promising body of preclinical work on SC-based medicine providing a potential cure for ED, rather than merely symptom relief, is indicative of the increasing interest in regenerative options for sexual medicine over the past decade. Clinical trials are currently recruiting patients to test the preclinical results in men with ED.

Effect of Thiazolidinediones Administration on Neurochemical Composition of MPG Neurons Related to Erection in OLETF Rat / 대한해부학회지

The main transmitter substance mediating erection is the nitric oxide released from the vascular endothelial cells of corpus cavernosum and from the nonadrenergic, noncholinergic nerve endings. In addition, some neurotransmitters, such as acetylcholine or vasoactive intestinal polypeptide (VIP), have been reported to play an important role in mediating the erection. Thus, autonomic neuropathy may cause erectile dysfunction, and in reality, it occurs frequently in individuals with diabetes mellitus (DM), in which polyneuropathy, including both peripheral somatic sensorimotor neuropathy and autonomic neuropathy, develops usually. Thiazolidinedione (TZD) is an insulin-sensitizing agent used for the treatment of type 2 DM with insulin resistance, and has been reported to ameliorate nephropathy, decrease plasma glucose level and reduce blood pressure. However, the effect of this drug on the neuropathy related to erectile dysfunction has never been proved. In the present study, to evaluate the effect of TZDs on the neuropathy concerned with erectile dysfunction, we examined neurochemical changes of major pelvic ganglion (MPG) neurons in Otsuka Long Evans Tokushima Fatty (OLETF) rats, genetic models with non-insulin-dependent DM, after TZDs (pioglitazone and rosiglitazone) treatment. Age-matched nondiabetic Long Evans Tokushima Otsuka (LETO) rats were used as controls. Nitric oxide synthase (NOS), tyrosine hydroxylase (TH), VIP, and neuropeptide Y (NPY) contents were measured in MPG neurons of LETO, OLETF and pioglitazone- or rosiglitazone-treated OLETF rats by morphometry. Compared to the corresponding LETO group, number of TH-, NOS- and VIP-immunoreactive (ir) neurons decreased, while that of NPY-ir neurons, which modulate noradrenergic vasoconstriction of penile arteries, increased in the MPG of the OLETF group. After administration of pioglitazone- or rosiglitazone to OLETF rats for 23 weeks, these neurochemical changes were recovered to the control levels of the LETO group, although some variations were accompanied. These results suggest that TZDs treatment may be helpful for the treatment of autonomic neuropathy concerned with erectile dysfunction.

Correlation of Functional Changes on Bladder and Proximal Urethra with Neuronal Nitric Oxide Synthase in Pelvic Ganglion Denervated Rats / 대한비뇨기과학회지

Injuries to the pelvic nerve plexus following major pelvic ablative surgery are commonly observed conditions in urologic field and often related to voiding difficulty with flaccid type of neurogenic bladder. The pathophysiological background for voiding difficulty is unknown and also it is difficult to investigate in human. The present study was undertaken to investigate the functional changes on the bladder and urethra in major pelvic ganglion denervated rats (experimental group). Injury to the pelvic nerve plexus was created by selective removal of bilateral major pelvic ganglions of mature Sprague-Dawley rats (male, 250-300 gm). One week after operation, urodynamic evaluation and NADPH diaphorase histochemistry were performed in each rat. The whole bladder wet weight and residual urine of experimental group significantly increased to 1.6 times and 29 times that of control group, respectively. For urodynamic investigations, the bladder and the urethra were completely disconnected by means of ligation between the bladder neck and the proximal urethra, and simultaneous recordings of the intravesical and proximal urethral pressure were performed. During simultaneous urethro-vesical filling in experimental group, vesical contraction and urethral relaxation were not induced. However, an administration of L-arginine (120 mg/kg intravenously), a nitric oxide substrate, resulted in a gradual decrease in urethral pressure when the bladder pressure was reached at submaximal level. On NADPH diaphorase histochemistry in control group, a large number of NADPH positive nerve fibers were found in the proximal urethra, whereas those were found less commonly in the bladder. In experimental group, the number of NOS positive nerve fibers in the bladder was similar to that in control group. But in the proximal urethra, the number of NOS positive nerve fibers (84.7 +/- 12.7) decreased significantly in contrast to that (185.9 +/- 56.3) in control group. These results indicate that failure to empty in neurogenic bladder may be resulted from relaxation impairment of bladder outlet, which can be explained by the reduction of neuronal NOS in the proximal urethra in experimental group.