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Hydrocephalus is characterized by enlargement of the cerebral ventricles, accompanied by distortion of the periventricular tissue. Patients with hydrocephalus usually experience urinary impairments. Although the underlying etiology is not fully described, the effects of hydrocephalus in the neuronal network responsible for the control of urination, which involves periventricular areas, including the periaqueductal gray (PAG) and the noradrenergic locus coeruleus (LC). In this study, we aimed to investigate the mechanisms behind urinary dysfunction in rats with kaolin-induced hydrocephalus. For that purpose, we used a validated model of hydrocephalus—the rat injected with kaolin in the cisterna magna—also presents urinary impairments in order to investigate the putative involvement of noradrenergic control from the brain to the spinal cord Onuf's nucleus, a key area in the motor control of micturition. We first evaluated bladder contraction capacity using cystometry. Since our previous characterization of the LC in hydrocephalic animals showed increased levels of noradrenaline, we then evaluated the noradrenergic innervation of the spinal cord's Onuf's nucleus by measuring levels of dopamine β-hydroxylase (DBH). We also evaluated the expression of the c-Fos protooncogene, the most widely used marker of neuronal activation, in the ventrolateral PAG (vlPAG), an area that plays a major role in the control of urination by its indirect control of the LC via pontine micturition center. Hydrocephalic rats showed an increased frequency of bladder contractions and lower minimum pressure. These animals also presented increased DBH levels at the Onuf´s nucleus, along with decreased c-Fos expression in the vlPAG. The present findings suggest that impairments in urinary function during hydrocephalus may be due to alterations in descending noradrenergic modulation. We propose that the effects of hydrocephalus in the decrease of vlPAG neuronal activation lead to a decrease in the control over the LC. The increased availability of noradrenaline production at the LC probably causes an exaggerated micturition reflex due to the increased innervation of the Onuf´s nucleus, accounting for the urinary impairments detected in hydrocephalic animals. The results of the study provide new insights into the neuronal underlying mechanisms of urinary dysfunction in hydrocephalus. Further research is needed to fully evaluate the translational perspectives of the current findings. [ABSTRACT FROM AUTHOR]

Introduction: Olfaction and its relation to human health is an area of growing interest. Although olfaction disorders have been considered a part of Kallmann syndrome, the role of olfactory dysfunction on spermatogenesis has not been studied yet. We studied if olfactory bulbectomy (OBX) causes dysfunction in spermatogenesis as a result of Onuf's nucleus damage. Methods: Twenty-eight male rats were divided into three groups: six as the control (G-1; n = 6), six as the only frontal burr hole applied animals SHAM (G-2; n = 6), and 16 as the study group (G-3; n = 16) in which OBX was performed. The animals were followed for 2 months. After the decapitation of the animals, olfactory bulb (OB) volumes (mm3), the neuron density of the Onuf's nucleus (n/mm3), and sperm density (n/mm3) were estimated stereologically and analyzed. Results: OB volumes (mm3), degenerated neuron density of Onuf's nucleus (n/mm3), and sperm numbers of control, SHAM, and study groups were estimated as: 4 ± 0.5; 6 ± 2 and 103.245 ± 10.841 in G-1; 3.5 ± 0.7; 14 ± 4 and 96.891 ± 9.569 in G-2; and 1.3 ± 0.3; 91 ± 17 and 73.561 ± 6.324 in G-3. The statistical results of degenerated neuron density of Onuf's nucleus and sperm numbers between groups are p < 0.005 for G-1/G-2; p < 0.0005 for G-2/G-3; and p < 0.00001 for G-1/G-3. Discussion: This study first time indicates that Onuf's nucleus degeneration secondary to OBX seems to be responsible for reduced sperm numbers. [ABSTRACT FROM AUTHOR]

Hydrocephalus is characterized by enlargement of the cerebral ventricles, accompanied by distortion of the periventricular tissue. Patients with hydrocephalus usually experience urinary impairments. Although the underlying etiology is not fully described, the effects of hydrocephalus in the neuronal network responsible for the control of urination, which involves periventricular areas, including the periaqueductal gray (PAG) and the noradrenergic locus coeruleus (LC). In this study, we aimed to investigate the mechanisms behind urinary dysfunction in rats with kaolin-induced hydrocephalus. For that purpose, we used a validated model of hydrocephalus—the rat injected with kaolin in the cisterna magna—also presents urinary impairments in order to investigate the putative involvement of noradrenergic control from the brain to the spinal cord Onuf’s nucleus, a key area in the motor control of micturition. We first evaluated bladder contraction capacity using cystometry. Since our previous characterization of the LC in hydrocephalic animals showed increased levels of noradrenaline, we then evaluated the noradrenergic innervation of the spinal cord’s Onuf’s nucleus by measuring levels of dopamine β-hydroxylase (DBH). We also evaluated the expression of the c-Fos protooncogene, the most widely used marker of neuronal activation, in the ventrolateral PAG (vlPAG), an area that plays a major role in the control of urination by its indirect control of the LC via pontine micturition center. Hydrocephalic rats showed an increased frequency of bladder contractions and lower minimum pressure. These animals also presented increased DBH levels at the Onuf´s nucleus, along with decreased c-Fos expression in the vlPAG. The present findings suggest that impairments in urinary function during hydrocephalus may be due to alterations in descending noradrenergic modulation. We propose that the effects of hydrocephalus in the decrease of vlPAG neuronal activation lead to a decrease in the control over the LC. The increased availability of noradrenaline production at the LC probably causes an exaggerated micturition reflex due to the increased innervation of the Onuf´s nucleus, accounting for the urinary impairments detected in hydrocephalic animals. The results of the study provide new insights into the neuronal underlying mechanisms of urinary dysfunction in hydrocephalus. Further research is needed to fully evaluate the translational perspectives of the current findings.

Patients with amyotrophic lateral sclerosis (ALS) do not develop oculomotor disturbances and vesicorectal dysfunction until end-stage disease owing to the survival of certain motor neurons (MNs), including oculomotor neurons and MNs within Onuf's nucleus. In sporadic ALS, adenosine deaminase acting on RNA 2 (ADAR2)-mediated editing of GluA2 mRNA at the Q/R site is compromised in lower MNs. We previously developed genetically modified mice with a conditional knockout of ADAR2 in cholinergic neurons (ADAR2 flox/flox /VAChT-Cre, Fast; AR2). These mice displayed slow and progressive lower motor neuron death with TAR DNA-binding protein 43 (TDP-43) pathology, attributable to insufficient editing at the GluA2 Q/R site due to ADAR2 deficiency. MN death was more common in fast-fatigable MNs owing to differential vulnerability under conditions of ADAR2 deficiency. Although facial and hypoglossal nerves were impaired in AR2 mice, cell death did not occur within the oculomotor nerve nucleus, as observed in patients with sporadic ALS. Since the basis for avoiding cystorectal damage in ALS is unknown, we compared the features of Onuf's nucleus MNs in 12-month-old AR2 mice with those in age-matched wild-type mice. Although the number of MNs was not significantly lower in AR2 mice, the neurons exhibited a shrunken morphology and TDP-43 pathology. Onuf's nucleus MNs could survive in an ADAR2-deficient state and mainly included fast fatigue-resistant (FR) and slow (S) MNs. In summary, FR and S MNs show increased resilience to ADAR2 deficiency, potentially participating in an important neuronal death avoidance mechanism in ALS. • MNs of Onuf's nucleus are spared in ADAR2 flox/flox /VAChT-Cre.Fast; AR2 mice. • MNs of Onuf's nucleus are small, with TDP-43 pathology, in AR2 mice. • MNs of Onuf's nucleus in AR2 mice might escape neuronal death. [ABSTRACT FROM AUTHOR]

Lumbosacral pathologies can lead to infertility. Onuf's nucleus changes in these pathologies may have a role in low sperm number. This study aims to investigate the relationship between Onuf's nucleus degeneration and sperm number following spinal subarachnoid haemorrhage. 22 rabbits were used. They were divided into three groups; five of them were used as the control (GI), five as the SHAM (GII) and twelve as the study groups (GIII). The study group received 0.7 ccs autologous blood into the spinal subarachnoid space at the T12‐L1 level. After two weeks, all animals were decapitated, and S1–S3 laminectomy was done. Neurodegenerative changes of Onuf's nucleus, pudendal ganglia (S3) following two weeks after spinal SAH, were examined; sperm numbers were calculated. Degenerated neuron density of the Onuf's nucleus (n/mm3), the pudendal ganglia (S3) (n/mm3) and mean sperm numbers were calculated as 5 ± 2, 8 ± 3/mm3 and 98.345 ± 12.776/mm3 in the control (GI), 20 ± 5/mm3, 243 ± 66/mm3 and 91.841 ± 9.654/mm3 in the SHAM (GII), 143 ± 39/mm3, 2,350 ± 320/mm3 and 68.549 ± 5.540/mm3 in the study group (GIII). In conclusion, there were statistically significant differences between groups. Onuf's nucleus may be responsible for decreased sperm number following spinal SAH. [ABSTRACT FROM AUTHOR]

Purpose/Aim of the study: Auerbach/Meissner network of lower abdominopelvic organs managed by parasympathetic nerve fibres of lumbosacral roots arising from Onuf's nucleus located in conus medullaris. Aim of this study is to evaluate if there is any relationship between Onuf's nucleus ischemia and Auerbach/Meissner network degeneration following spinal subarachnoid haemorrhage (SAH). Materials and Methods: Study was conducted on 24 male rabbits included control (Group I, n = 5), serum saline-SHAM (Group II, n = 5), and spinal SAH (Group III, n = 14) groups. Spinal SAH performed by injecting homologous blood into subarachnoid space at Th12–L4 level and followed three weeks. Live and degenerated neuron densities of Onuf's nucleus, Auerbach and Meissner ganglia (n/mm3) were determined by Stereological methods. Results: The mean degenerated neuron density of Onuf's nucleus was significantly higher in Group III than in Groups I–II (152 ± 26, 2 ± 1 and 5 ± 2/mm3 respectively, p < 0.005). The degenerated neuron density of Auerbach's ganglia was significantly higher in Group III than in Groups I–II (365 ± 112, 3 ± 1 and 9 ± 3/mm3 respectively, p < 0.005). The degenerated neuron density of Meissner's ganglia was significantly higher in Group III than in Groups I–II (413 ± 132, 2 ± 1 and 11 ± 4/mm3 respectively, p < 0.005). Conclusions: Onuf's nucleus pathologies should be considered as Auerbach/Meissner ganglia degeneration and also related Hirschsprung-like diseases in the future. [ABSTRACT FROM AUTHOR]

Although posttraumatic mesenteric artery ischemia is attributed to various etiologies, sacral parasympathetic network/mesenteric artery relations have not been studied so far. The primary objective of this study is to elucidate whether there is a relationship between Onuf's nucleus ischemia and mesenteric artery vasospasm following subarachnoid hemorrhage (SAH). This study was conducted on 22 rabbits. The animals were grouped as follows: 5 of animals control, 5 SHAM which saline was given, and 12 animals study group that was homologous blood injected into the spinal subarachnoid space at the Lı level. Neurodegeneration in Onuf's nucleus, axonal degeneration of S2 roots, and mesenteric arteries vasospasm indexes (VSI; Wall surface/Lumen surface), brachias of mesentery arteries in various tissues and ischemic mucosal changes of intestines of all animals were determined histopathologically. Important degenerative changes were detected in axons in S2 roots and Onuf's nucleus in severe mesenteric artery vasospasm observed. The mean degenerated neuron density of Onuf's nucleus (n/mm3), degenerated axon density in S2 roots (n/mm2), and VSI values of mesenteric arteries of control, SHAM, and study groups were estimated as 5.00 ± 1.58, 4.00 ± 1.58, 1.76 ± 0.13; 18.29 ± 4.31, 11.00 ± 2.24, 2.23 ± 0.20; and 135.21 ± 30.75, 117.33 ± 22.11, 2.81 ± 0.44, respectively. Statistical analyses between the VSI values, mucosal ischemic changes degenerated neurons in Onuf's nucleus, and axons in S2 levels were meaningful (p < 0.005). We interestingly noticed that Onuf's nucleus–S2 roots complex degeneration plays an important role in mesenteric artery vasospasm and the development of intestinal ischemic mucosal changes following SAH which has not been extensively mentioned in the literature. • Mesentery artery spasm is a common problem, but diagnosed rarely. • Spinal cord pathologies could be most important factors on the development of mesenteric artery circulation disorders. • The relationship between these two entities are not well established. [ABSTRACT FROM AUTHOR]

Objectives: To examine the effect of intrathecal (i.t.) serotonin (5‐hydroxytryptamine) 5‐HT7 agonist administration on voiding function in the urethane‐anesthetised rat, and the change in 5‐HT7 receptor (5‐HT7R) expression in the lumbosacral cord Onuf's nucleus after spinal cord injury (SCI). Materials and methods: In all, 32 female Sprague–Dawley (SD) rats were equally divided into a spinally intact (SI) group and SCI group (n = 16 each). At 8 weeks after transection, half of the rats underwent continuous cystometry under urethane anaesthesia, and the 5‐HT7R‐selective agonist LP44 was given (i.t.). The remaining rats were used for pseudorabies (PRV) retrograde tracing, immunofluorescence, and Western Blot. Results: LP44 administered i.t. had no effect in the SI rats. In SCI rats, LP44 (1–30 μg/kg) induced significant dose‐dependent increases in micturition volume, voiding efficiency, number of high‐frequency oscillations per micturition; and decreases in residual volume, bladder capacity, peak bladder pressure, threshold pressure and non‐voiding contractions. The 5‐HT7R antagonist, SB‐269970 (10 μg/kg), partially reversed LP44‐induced changes. Using PRV retrograde tracing and immunofluorescence, 5‐HT7Rs were found in the L6–S1 spinal cord Onuf's nucleus in both SI and SCI rats, but the expression was significantly greater in the SCI rats. Western blot showed significantly more 5‐HT7Rs in the ventral L6–S1 spinal cord in SCI rats. Conclusion: A 5‐HT7R agonist, given i.t., improved voiding efficiency in urethane‐anesthetised SCI rats, and the 5‐HT7R was significantly up‐regulated in the lumbosacral cord Onuf's nucleus. If valid for humans, these findings suggest that the 5‐HT7R could be a target for therapeutic interventions. [ABSTRACT FROM AUTHOR]

In order to investigate lower urinary tract function in hereditary spastic paraplegia (HSP), we recruited 12 HSP patients: 8 men, 4 women; mean age, 64.6 years; mean disease duration, 18.9 years; walk without cane, 2, walk with cane, 6, wheelchair bound, 3. We performed urinary symptom questionnaires and a urodynamic testing in all patients. As a result, urinary symptoms were observed in all but 3, including urinary urgency/frequency (also called overactive bladder) in 9 and hesitancy/poor stream in 6. Urodynamic abnormalities included detrusor overactivity during bladder filling in 10, underactive detrusor on voiding in 8 (detrusor hyperactivity with impaired contraction [DHIC] in 5), detrusor-sphincter dyssynergia (DSD) on voiding in 3, and post-void residual in 5. Sphincter electromyography showed neurogenic motor unit potential in 4. In conclusion, we observed high frequency of urinary symptoms in HSP. Urodynamics indicated that the main mechanism is DHIC with/without DSD for their urinary symptom, and sacral cord involvement in some cases. These findings facilitate patients' care including clean, intermittent catheterization. [ABSTRACT FROM AUTHOR]

The role of gonadal steroids in sexual differentiation of the central nervous system (CNS) is well established in rodents, but no study to date has manipulated androgens prenatally and examined their effects on any CNS structure in a primate. Onuf's nucleus is a column of motoneurons in the sacral spinal cord that innervates the striated perineal muscles. This cell group is larger in males than in females of many species, due to androgens acting during a sensitive perinatal period. Here, we examined Onuf's nucleus in 21 adult rhesus monkeys, including control males and females, as well as males whose mothers had been treated with an anti-androgen or testosterone during gestation. We found a robust sex difference, with more motoneurons in control males than in females. The soma size of Onuf's nucleus motoneurons was also marginally larger in males. Treatment with the anti-androgen flutamide for 35–40 days during early gestation partially blocked masculinization of Onuf's nucleus: motoneuron number in flutamide-treated males was decreased relative to control and testosterone-treated males, but remained greater than in females, with no effect on cell size. A control motor nucleus that innervates foot muscles (Pes9) showed no difference in motoneuron number or size between control males and females. Prenatal testosterone treatment of males did not alter Onuf's nucleus motoneuron number, but did increase the size of both Onuf's and Pes9 motoneurons. Thus, prenatal androgen manipulations cause cellular-level changes in the primate CNS, which may underlie previously observed effects of these manipulations on behavior. [ABSTRACT FROM AUTHOR]

We examined the phosphorylated 43-kDa TAR DNA-binding protein (pTDP-43) inclusions as well as neuronal loss in full-length spinal cords and five selected regions of the central nervous system from 36 patients with amyotrophic lateral sclerosis (ALS) and 10 age-matched normal controls. The most severe neuronal loss and pTDP-43 lesions were seen in lamina IX motor nuclei columns 4, 6, and 8 of lower cervical segments and in columns 9-11 of lumbosacral segments. Severity of pTDP-43 pathology and neuronal loss correlated closely with gray and white matter oligodendroglial involvement and was linked to onset of disease, with severe involvement of columns 4, 6, and 8 of upper extremity onset cases and severe involvement of columns of 9, 10, and 11 in cases with lower extremity onset. Severe TDP-43 lesions and neuronal loss were observed in stage 4 cases and sometimes included Onuf's nucleus. Notably, three cases displayed pTDP-43 aggregates in the midbrain oculomotor nucleus, which we had not seen previously even in cases with advanced (i.e., stage 4) pathology. pTDP-43 aggregates were observed in neurons of Clarke's column in 30.6 % of cases but rarely in the intermediolateral nucleus (IML). Gray matter oligodendroglial pTDP-43 inclusions were present in areas devoid of neuronal pTDP-43 aggregates and neuronal loss. Taken together, our findings indicate that (1) the dorsolateral motor nuclei columns of the cervical and lumbosacral anterior horn may be the earliest foci of pTDP-43 pathology in the spinal cord, (2) gray matter oligodendroglial involvement is an early event in the ALS disease process that possibly heralds subsequent involvement of neurons by pTDP-43 pathology, and (3) in some very advanced cases, there is oculomotor nucleus involvement, which may constitute an additional neuropathological stage (designated here as stage 5) of pTDP-43 pathology in ALS.

Introduction The physiological component of ejaculation shows parallels with that of micturition, as both are essentially voiding activities. Both depend on supraspinal influences to orchestrate the characteristic pattern of activity in the pelvic organs. Unlike micturition, little is known about the supraspinal pathways involved in ejaculation and female orgasm. Aim To identify brainstem regions activated during ejaculation and female orgasm and to compare them with those activated during micturition. Methods Ejaculation in men and orgasm in women were induced by manual stimulation of the penis or clitoris by the participants' partners. Positron emission tomography ( PET) with correction for head movements was used to capture the pattern of brain activation at the time of sexual climax. Main Outcome Measures PET scans showing areas of activation during sexual climax. Results Ejaculation in men and orgasm in women resulted in activation in a localized region within the dorsolateral pontine tegmentum on the left side and in another region in the ventrolateral pontine tegmentum on the right side. The dorsolateral pontine area was also active in women who attempted but failed to have an orgasm and in women who imitated orgasm. The ventrolateral pontine area was only activated during ejaculation and physical orgasm in women. Conclusion Activation of a localized region on the left side in the dorsolateral pontine tegmentum, which we termed the pelvic organ-stimulating center, occurs during ejaculation in men and physical orgasm in women. This same region has previously been shown to be activated during micturition, but on the right side. The pelvic organ-stimulating center, via projections to the sacral parasympathetic motoneurons, controls pelvic organs involved in voiding functions. In contrast, the ventrolateral pontine area, which we term the pelvic floor-stimulating center, produces the pelvic floor contractions during ejaculation in men and physical orgasm in women via direct projections to pelvic floor motoneurons. Huynh HK, Willemsen ATM, Lovick TA, and Holstege G. Pontine control of ejaculation and female orgasm. J Sex Med 2013;10:3038-3048. [ABSTRACT FROM AUTHOR]

The contraction of the detrusor muscle causes the urinary bladder and its mass peristaltic movement, leading to micturition. The vesical plexus of nerves, composed of fibers from the inferior hypogastric plexus, supplies the urinary bladder. The brain plays a crucial part in developing and maintaining bladder control, although its specific involvement in urgency and urine leakage is not well understood. The critical components in the neural control of the bladder and its regulation are the pontine micturition center (located in the mediodorsal aspect of the pons) and the Onuf's nucleus, also known as the sacral micturition center (located between the sacral S2 and S4 segments). The most important cause of a neurogenic bladder is damage or lesions of the spinal cord affecting the pontine micturition center, Onuf's nucleus, or damage to the motor neurons between the pontine and the sacral centers of micturition. Neurogenic bladder can be of several types based on the location of the lesions, such as the autonomous bladder, spastic bladder, atonic bladder, and cortical bladder, all were presented with a unique clinical picture. The classical approach to a case of neurogenic bladder involves a complete assessment of the neurologic system and of pelvic anatomy, while neurogenic bladder rehabilitation may include a bladder retraining program involving intermittent catheterization, timed voiding, medications, and lifestyle modifications. This review article attempts to correlate the neurogenic bladder with various anatomical aspects related to the micturition center in the brain and spinal cord and their control over the urinary bladder, as well as the classical approach toward such a case of neurogenic bladder., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2022, Kumar et al.)

During childbirth, a combinatorial injury occurs and can result in stress urinary incontinence (SUI). Simulated childbirth injury, consisting of vaginal distension (VD) and pudendal nerve crush (PNC), results in slowed recovery of continence, as well as decreased expression of brain-derived neurotrophic factor (BDNF), a regenerative cytokine. Electrical stimulation has been shown to upregulate BDNF in motor neurons and facilitate axon regrowth through the increase of βII-tubulin expression after injury. In this study, female rats underwent selective pudendal nerve motor branch (PNMB) stimulation after simulated childbirth injury or sham injury to determine whether such stimulation affects bladder and anal function after injury and whether the stimulation increases BDNF expression in Onuf's nucleus after injury. Rats received 4 h of VD followed by bilateral PNC and 1 h of subthreshold electrical stimulation of the left PNMB and sham stimulation of the right PNMB. Rats underwent filling cystometry and anal pressure recording before, during, and after the stimulation. Bladder and anal contractile function were partially disrupted after injury. PNMB stimulation temporarily inhibited bladder contraction after injury. Two days and 1 wk after injury, BDNF expression in Onuf's nucleus of the stimulated side was significantly increased compared with the sham-stimulated side, whereas βII-tubulin expression in Onuf's nucleus of the stimulated side was significantly increased only 1 wk after injury. Acute electrical stimulation of the pudendal nerve proximal to the crush site upregulates BDNF and βII-tubulin in Onuf's nucleus after simulated childbirth injury, which could be a potential preventive option for SUI after childbirth injury. [ABSTRACT FROM AUTHOR]

We previously reported that in a eusocial rodent, the naked mole-rat (Heterocephalus glaber), traditional neural sex differences were absent; instead, neural dimorphisms were associated with breeding status. Here we examined the same neural regions previously studied in naked mole-rats in a second eusocial species, the Damaraland mole-rat (Fukomys damarensis). Damaraland mole-rats live in social groups with breeding restricted to a small number of animals. However, colony sizes are much smaller in Damaraland mole-rats than in naked mole-rats and there is consequently less reproductive skew. In this sense, Damaraland mole-rats may be considered intermediate in social organization between naked mole-rats and more traditional laboratory rodents. We report that, as in naked mole-rats, breeding Damaraland mole-rats have larger volumes of the principal nucleus of the bed nucleus of the stria terminalis and paraventricular nucleus of the hypothalamus than do subordinates, with no effect of sex on these measures. Thus, these structures may play special roles in breeders of eusocial species. However, in contrast to what was seen in naked mole-rats, we also found sex differences in Damaraland mole-rats: volume of the medial amygdala and motoneuron number in Onuf's nucleus were both greater in males than in females, with no significant effect of breeding status. Thus, both sex and breeding status influence neural morphology in Damaraland mole-rats. These findings are in accord with the observed sex differences in body weight and genitalia in Damaraland but not naked mole-rats. We hypothesize that the increased sexual dimorphism in Damaraland mole-rats relative to naked mole-rats is related to reduced reproductive skew. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract: Naked mole-rats are eusocial rodents that live in large social groups with a strict reproductive hierarchy. In each colony only a few individuals breed; all others are non-reproductive subordinates. We previously showed that breeders have increased volume of several brain regions linked to reproduction: the paraventricular nucleus of the hypothalamus (PVN), the principal nucleus of the bed nucleus of the stria terminalis (BSTp), and the medial amygdala (MeA). Breeders also have more large motoneurons in Onuf''s nucleus (ON) in the spinal cord, a cell group innervating perineal muscles that attach to the genitalia. Here, we sought to determine triggers for the neural changes seen in breeders. Specifically, we compared four groups of animals: subordinates, paired animals that did not reproduce, gonadally intact breeders, and gonadectomized breeders. We find that pairing alone is sufficient to cause breeder-like changes in volume of the PVN and cell size distribution in ON. In contrast, increases in BSTp volume were seen only in animals that actually reproduced. Those changes that were seen in successful breeders appear to be independent of gonadal steroids because long-term gonadectomy did not reverse the breeder-like neural changes in the PVN, BSTp or ON, although a trend for gonadectomized animals having larger MeA volumes was detected. Thus, neural changes associated with breeding status in naked mole-rats may be triggered by different aspects of the social and reproductive environment; once changes occur they are largely independent of gonadal hormones and may be permanent. [Copyright &y& Elsevier]

Abstract: Clinical information on familial amyotrophic lateral sclerosis (FALS) with Gly72Ser mutation in the Cu/Zn superoxide dismutase-1 (SOD1) gene has been limited and autopsy findings remain to be clarified. We describe one Japanese family with ALS carrying Gly72Ser mutation in the SOD1 gene, in which autopsy was performed on one affected member. The autopsied female patient developed muscle weakness of the left thigh at age 66 and showed transient upper motor neuron signs. She died of respiratory failure 13months after onset without artificial respiratory support. There were no symptoms suggesting bladder or rectal dysfunction throughout the clinical course. Her brother with ALS was shown to have Gly72Ser mutation in the SOD1 gene. Histopathologically, motor neurons were markedly decreased throughout the whole spinal cord, whereas corticospinal tract involvement was very mild and was demonstrated only by CD68 immunohistochemistry. Degeneration was evident in the posterior funiculus, Clarke''s nucleus, posterior cerebellar tract, and Onuf''s nucleus. Neuronal hyaline inclusions were rarely observed in the neurons of the spinal cord anterior horn including Onuf''s nucleus, and were immunoreactive for SOD1. To date, neuron loss in Onuf''s nucleus has hardly been seen in ALS, except in the patients showing prolonged disease duration with artificial respiratory support. Involvement of Onuf''s nucleus may be a characteristic pathological feature in FALS with Gly72Ser mutation in the SOD1 gene. [Copyright &y& Elsevier]

Abstract: In the macaque cerebral cortex, the SPP1 (secreted phosphoprotein 1) gene is mainly expressed in corticospinal neurons. In this study, we found that SPP1 was principally expressed in motor neurons in lamina IX of the macaque spinal cord. The expression level varied among different spinal segments and correlated positively with neuron size. The expression was weak in Errγ-positive neurons, presumably gamma motor neurons, and in neurons in sacral Onuf''s nucleus. These results suggest that SPP1 is a molecular characteristic of spinal motor neurons and is preferentially expressed in neurons with high conduction velocities. [Copyright &y& Elsevier]

Machado–Joseph disease (MJD) is an autosomal dominant neurodegenerative disease caused by an expansion of CAG repeats in the MJD1 gene, in which lower urinary tract dysfunction is known to be the most commonly encountered autonomic failure. However, it remains unclear whether Onuf’s nucleus (ON), which plays major roles in the micturition reflex and voluntary continence, degenerates during the disease process. In the present study, we conducted a morphometric and immunohistochemical study of ON, together with the lateral nuclear group (LNG) of the sacral anterior horns, in seven patients with MJD. When compared with controls, the number of lower motor neurons in both ON and LNG was significantly smaller in the MJD patients, the former being inversely correlated with the size of the expanded CAG repeats. Notably, MJD patients with a large CAG-repeat expansion showed an ON-predominant pattern of neuronal loss, while in the remaining patients, ON and LNG were affected to a similar degree, or rather an LNG-predominant pattern of neuronal loss was evident. Moreover, when adjusted for age, the degree of neuronal loss in both ON and LNG was significantly correlated with the extent of expansion of the CAG repeats. In MJD, the remaining lower motor neurons in ON often exhibited ataxin-3- or 1C2-immunoreactive (ir) neuronal intranuclear inclusions, while no pTDP-43-ir neuronal cytoplasmic inclusions were present in these neurons. In conclusion, the present findings strongly suggest that neuronal loss in ON, the degree of which is highly influenced by the extent of expansion of CAG repeats, is a consistent feature in MJD. [ABSTRACT FROM AUTHOR]

Abstract: Onuf''s nucleus in the lumbosacral spinal cord, comprising somatic motoneurons that innervate the pelvic floor muscles via the pudendal nerve, shares some characteristics with the autonomic preganglionic neurons and functions in coordination with the autonomic nervous system. In mouse, neurons projecting to the urethral sphincter and ischiocavernosus muscles form the dorsolateral (DL) nucleus at the caudal lumbar levels, whereas neurons projecting to the limb and hip joint muscles comprise the retrodorsolateral and ventral nucleus, as well as the DL nucleus at the rostral lumbar levels. The results of the present study in mouse revealed that the expression pattern of a LIM homeodomein protein Islet-1, an embryonic marker for motoneurons in the spinal cord, was different among motoneuronal groups at the prenatal stage (embryonic days 13.5–15.5); the highest expression was observed in the DL at the caudal lumbar cord, whereas there was little expression in the lateral part of the rostral DL. Islet-1 expression was also observed in the parasympathetic preganglionic neurons at the sacral spinal cord. These findings provide evidence that the DL neurons at the caudal lumbar cord, corresponding to Onuf''s nucleus, are chemically distinct among the motoneuronal groups at the prenatal stages. This differential Islet-1 expression among the motoneuronal groups suggests that Islet-1 not only leads to a motoneuronal lineage, but also to the differentiation of motoneuronal subsets in the lumbosacral spinal cord. [Copyright &y& Elsevier]

Multiple system atrophy (MSA) is a neurodegenerative disease presenting with a combination of parkinsonian, cerebellar, and autonomic (including cardiovascular, urinary, and anorectal) dysfunction. It is pathologically defined, but at present lacks a definitive clinical diagnostic test. The majority of patients with probable MSA have an abnormal sphincter EMG. Patients with idiopathic Parkinson’s disease do not show marked sphincter EMG abnormalities. Therefore, these abnormalities can be used to distinguish MSA from idiopathic Parkinson’s disease in the first 5 years after disease onset. In contrast, similar sphincter EMG abnormalities are found in some, though not many, patients with dementia with Lewy bodies, pure autonomic failure, progressive supranuclear palsy, and spinocerebellar ataxia type 3. Thus, the limitations of the sphincter EMG test should also be kept in mind. Sphincter EMG and relevant sacral autonomic tests are diagnostic tools for autonomic disorders, reflecting the common and significant involvement of the sacral cord in MSA. [ABSTRACT FROM AUTHOR]

Chronic stress is known to induce disorders of reproductive neuroendocrine functions. Motoneurons of the spinal nucleus of the bulbocavernosus (SNB) in male rats play an important role in copulatory behavior. In the present study, it was examined whether chronic stress would alter synaptic organization of the SNB motoneurons and whether androgen would modify the changes under chronic stress. Five male rats were under restraint stress for 5 days per week for 3 weeks, and five males implanted subcutaneously with Silastic capsules containing testosterone were also exposed to stress. Five males served as unstressed controls. After 3 weeks of restraint stress, cholera toxin-horseradish peroxidase (CT-HRP) was injected into the bulbocavernosus muscles and animals were killed 2 days later. The spinal cords containing the SNB were dissected, processed with a modified tetramethylbenzidine (TMB) method for visualization of retrogradely transported CT-HRP, and examined ultrastructurally. Neuronal structures apposing the membranes of 150 SNB motoneurons (total for three groups) were analyzed by measuring the percentage of somatic membranes covered by synaptic contacts. The mean percentage of somatic membranes covered by synapses in males exposed to chronic stress was significantly less than that in controls or stressed males treated with testosterone. Size and number of synaptic contacts per unit length of somatic membranes in males exposed to stress were also significantly less than those in controls or stressed males treated with testosterone. There was no significant difference in any of the parameters between controls and stressed males treated with testosterone. Changes in plasma levels of testosterone showed the same profile as changes in the synaptic contacts. These results suggest that the SNB motoneurons of male rats exposed to chronic stress retain a considerable synaptic plasticity in response to androgen, and that androgen treatment can rescue the SNB system in male rats when under chronic restraint stress. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study was to characterize the spinal distribution of afferent and efferent pathways that innervate the levator ani (LA) muscle in the female squirrel monkey. Study design: Cholera toxin B (CTB) was injected unilaterally into the LA muscle of 5 monkeys to identify primary sensory neurons in the dorsal root ganglia (DRG) and motor neurons in the spinal cord that contribute fibers to the LA nerve. Fluoro-Gold (FG) was injected into the external anal sphincter of 2 of these animals to label pudendal motor neurons (1 of these animals underwent unilateral LA neurectomy before CTB injection). Spinal cord and DRG were processed for immunofluorescence 3 to 7 days after injections. Results: Retrograde transport of CTB from the LA muscle labeled primary afferent neurons in the ipsilateral DRG, their central projections, and motor neurons in the medial portion of the ipsilateral ventral horn of the spinal cord (L7-S2 segments). Injection of FG into the external anal sphincter labeled cells in Onuf's nucleus, primarily in L7. Importantly, CTB-labeled LA motor neurons were virtually absent in Onuf's nucleus, where all pudendal motor neurons are located. CTB-labeled processes were observed within Onuf's nucleus, adjacent to FG-labeled pudendal motor neurons, and appeared to derive from dendrites of LA motor neurons that project into Onuf's nucleus. Conclusion: The LA muscle has a distinct innervation with very little or no contribution from the pudendal nerve. The intriguing labeling of LA neural elements within a nucleus that innervates the external urethral and anal sphincters (involved in pelvic visceral control) may represent a neuroanatomic substrate for physiologic integration of spinal and supraspinal inputs for the coordination of pelvic floor and visceral activity. [ABSTRACT FROM AUTHOR]

GAP-43 is normally produced by neurons during developmental growth and axonal regeneration, but it is also expressed in specific regions of the normal adult nervous system. We studied the protein expression of GAP-43 within the conus medullaris portion of the spinal cord in adult male rats. Immunohistochemistry for choline acetyltransferase (ChAT) was first performed to identify specific efferent autonomic and motor nuclei in lumbosacral segments of the spinal cord. Adjacent sections were then processed for GAP-43 immunoreactivity (IR). We show GAP-43 IR in the superficial portion of the dorsal horn, the intermediolateral nucleus, and the dorsal commissural tract. We also demonstrate a differential distribution of GAP-43 IR between different motor nuclei of the conus medullaris. Using densitometry, the most prominent GAP-43 IR was detected in the dorsolateral and dorsomedial motor nuclei, which represent the human Onuf’s nucleus homologue. Confocal microscopy of double immunofluorescent labeling for ChAT and GAP-43 demonstrate GAP-43 IR in the neuropil of the autonomic and motor nuclei, and many of the GAP-43 IR arbors are in close apposition with the efferent cholinergic neurons. We note that the efferent neurons of both the autonomic and somatic nuclei, which are ultimately responsible for the integrated normal control of the lower urinary tract, bowel and sexual functions, are heavily innervated by GAP-43 enriched projections.We speculate that these functionally related neurons retain a physiological GAP-43-associated synaptic plasticity throughout adult life. [ABSTRACT FROM AUTHOR]

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Stress urinary incontinence (SUI) in women is prevalent, and there are no globally developed or widely approved drugs for the disease. One strategy for improving urinary continence is to augment the function of the urethral rhabdosphincter through neuropharmacology. The present review describes the innervation of the urethra, and the role of the central nervous system in controlling nerve activity. Targeting serotonin and norepinephrine (or noradrenaline) receptors in Onuf''s nucleus is shown to augment the function of the urethral rhabdosphincter by increasing pudendal nerve efferent activity. It is proposed that the ability of serotonin and norepinephrine to enhance the effects of glutamate (the primary excitatory neurotransmitter for pudendal sphincter motor neurons) while having no direct effects of their own, allow facilitation of rhabdosphincter activity during urine storage while allowing complete relaxation during micturition. Duloxetine, a potent and balanced dual serotonin (5-HT)-norepinephrine reuptake inhibitor (SNRI), potentiates these physiological effects of endogenous serotonin and norepinephrine (by inhibiting the reuptake of these neurotransmitters in the pre-synaptic element) and thereby enhances the central nervous system''s natural continence control mechanisms. [Copyright &y& Elsevier]

Although the guinea pig is used widely in experimental medical research, including in studies on micturition control, the spinal origin of preganglionic parasympathetic bladder and somatic external urethral sphincter motoneurons is not known. In the male guinea pig using wheat germ agglutinin-conjugated horseradish peroxidase and dextran Alexa Fluor© 488/568 tracers, preganglionic parasympathetic bladder motoneurons were observed in the ventrolateral part of the intermediolateral cell group of the first sacral segment. The external urethral sphincter motoneurons were found to be located in the ventral horn of the first sacral segment, in a cell group corresponding with the nucleus of Onuf in cat and human. [Copyright &y& Elsevier]

This article discusses a model of the electrical behavior of an external urethral sphincter motoneuron, based on morphological parameters like soma size, dendritic diameters and spatial dendritic configuration, and several electrical parameters. Because experimental data about the exact ion conductance mix of external urethral sphincter neurons is scarce, the gaps in knowledge about external urethral sphincter motoneurons were filled in with known data of α-mononeurons. The constructed compartmental model of motoneurons of Onuf's nucleus contains six voltage-dependent ionic conductances; a fast sodium and potassium conductance and an anomalous rectifier in the soma; a fast delayed rectifier type potassium conductance and a fast sodium conductance in the initial axon segment; an L-type calcium channel in the dentritic compartments. This paper considers the simulation of external urethral sphincter motoneuron responses to current injections that evoke bistable behavior. Simulations show self-sustained discharge following a depolarizing pulse through the microelectrode; the firing was subsequently terminated by a short hyperpolarizing pulse. This behavior is highly functional for neurons that have to exhibit prolonged activation during sphincter closure. In addition to these 'on' and 'off' responses, we also observed a particular firing behavior in response to long-lasting triangular current pulses. When the depolarizing current was slowly increased and then decreased (triangular pulse) the firing frequency was higher during the descending phase than during the initial ascending phase. [ABSTRACT FROM AUTHOR]

Onuf's nucleus is a small group of cells which are located mainly in the anterior horn of the second sacral segment of the spinal cord. This paper describes the history of studies relating to this nucleus including a discussion of its relation with the various pathological studies which have been made. [ABSTRACT FROM AUTHOR]

The location, number and size of the motoneurons innervating the ischiocavernosus muscle, identified by means of horseradish-peroxidase (HRP) retrograde transport, were studied (1) in adult untreated male rats, (2) in adult male rats castrated before puberty, and (3) in adult male rats castrated before puberty and injected with testosterone from the day of castration. After injection of HRP into the ischiocavernosus muscle, labeled motoneurons were found in the dorsolateral and dorsomedial columns of the lamina IX, at the level of L6 and S1 segments of the spinal cord. Morphometric analysis demonstrated that prepubertal castration induces a statistically significant reduction in the somatic and nuclear areas (40% and 35%, respectively, if compared to those of the control rats) of both the dorsolateral and dorsomedial motoneurons, but does not affect their number. The effects of castration are prevented by exogenous testosterone. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Neurology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Central distribution of efferent and afferent components of the pudendal nerve was examined in the rat by the horseradish peroxidase (HRP) method after HRP application to the central cut end of the pudendal nerve. The pudendal motoneurons were located in the dorsolateral, dorsomedial and lateral groups at L5 and L6. Each of the dorsolateral and dorsomedial groups constituted a slender longitudinal cell column. Pudendal motoneurons in the lateral group were scattered at L5, rostrodorsally to the dorsolateral group. The neurons in the dorsolateral and lateral groups were labelled with HRP applied to the nerve branch innervating the ischiocavernosus and sphincter urethrae muscles. The neurons in the dorsomedial group were labelled with HRP applied to the branch supplying the sphincter ani externus and bulbospongiosus muscles. Some dendrites of pudendal motoneurons in the dorsomedial group extended to the contralateral dorsomedial group. These crossing dendrites were observed not only in male rats but also in female. The average number of the pudendal motoneurons in the dorsolateral and dorsomedial groups were larger in male rats than in female. A few neurons of the intermediolateral nucleus at upper L6 were also labelled with HRP applied to the dorsalis penis (clitoridis) nerve. Axon terminals of the pudendal nerve were distributed, bilaterally with an ipsilateral predominance, to the gracile nucleus, as well as to the dorsal horn and dorsal commissural gray from L4 to S2. A few labelled axons were seen in the intermediolateral nucleus at L6 and S1. Axon terminals from the dorsalis penis nerve were distributed more medially in the dorsal horn than those from the perinealis nerve. [ABSTRACT FROM AUTHOR]