1
|
Steuer I, Guertin PA. Central pattern generators in the brainstem and spinal cord: an overview of basic principles, similarities and differences. Rev Neurosci 2019; 30:107-164. [PMID: 30543520 DOI: 10.1515/revneuro-2017-0102] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/30/2018] [Indexed: 12/11/2022]
Abstract
Central pattern generators (CPGs) are generally defined as networks of neurons capable of enabling the production of central commands, specifically controlling stereotyped, rhythmic motor behaviors. Several CPGs localized in brainstem and spinal cord areas have been shown to underlie the expression of complex behaviors such as deglutition, mastication, respiration, defecation, micturition, ejaculation, and locomotion. Their pivotal roles have clearly been demonstrated although their organization and cellular properties remain incompletely characterized. In recent years, insightful findings about CPGs have been made mainly because (1) several complementary animal models were developed; (2) these models enabled a wide variety of techniques to be used and, hence, a plethora of characteristics to be discovered; and (3) organizations, functions, and cell properties across all models and species studied thus far were generally found to be well-preserved phylogenetically. This article aims at providing an overview for non-experts of the most important findings made on CPGs in in vivo animal models, in vitro preparations from invertebrate and vertebrate species as well as in primates. Data about CPG functions, adaptation, organization, and cellular properties will be summarized with a special attention paid to the network for locomotion given its advanced level of characterization compared with some of the other CPGs. Similarities and differences between these networks will also be highlighted.
Collapse
Affiliation(s)
- Inge Steuer
- Neuroscience Unit, Laval University Medical Center (CHUL - CHU de Québec), 2705 Laurier Blvd, Quebec City, Quebec G1V 4G2, Canada
| | - Pierre A Guertin
- Neuroscience Unit, Laval University Medical Center (CHUL - CHU de Québec), 2705 Laurier Blvd, Quebec City, Quebec G1V 4G2, Canada
- Faculty of Medicine, Department of Psychiatry and Neurosciences, Laval University, Quebec City, Quebec G1V 0A6, Canada
| |
Collapse
|
2
|
de Groat WC, Yoshimura N. Anatomy and physiology of the lower urinary tract. HANDBOOK OF CLINICAL NEUROLOGY 2015; 130:61-108. [PMID: 26003239 DOI: 10.1016/b978-0-444-63247-0.00005-5] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Functions of the lower urinary tract to store and periodically eliminate urine are regulated by a complex neural control system in the brain, spinal cord, and peripheral autonomic ganglia that coordinates the activity of smooth and striated muscles of the bladder and urethral outlet. Neural control of micturition is organized as a hierarchic system in which spinal storage mechanisms are in turn regulated by circuitry in the rostral brainstem that initiates reflex voiding. Input from the forebrain triggers voluntary voiding by modulating the brainstem circuitry. Many neural circuits controlling the lower urinary tract exhibit switch-like patterns of activity that turn on and off in an all-or-none manner. The major component of the micturition switching circuit is a spinobulbospinal parasympathetic reflex pathway that has essential connections in the periaqueductal gray and pontine micturition center. A computer model of this circuit that mimics the switching functions of the bladder and urethra at the onset of micturition is described. Micturition occurs involuntarily during the early postnatal period, after which it is regulated voluntarily. Diseases or injuries of the nervous system in adults cause re-emergence of involuntary micturition, leading to urinary incontinence. The mechanisms underlying these pathologic changes are discussed.
Collapse
Affiliation(s)
- William C de Groat
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
| | - Naoki Yoshimura
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| |
Collapse
|
3
|
Hotta H, Watanabe N. Gentle Mechanical Skin Stimulation Inhibits Micturition Contractions via the Spinal Opioidergic System and by Decreasing Both Ascending and Descending Transmissions of the Micturition Reflex in the Spinal Cord. PLoS One 2015; 10:e0135185. [PMID: 26252000 PMCID: PMC4529237 DOI: 10.1371/journal.pone.0135185] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 07/19/2015] [Indexed: 01/23/2023] Open
Abstract
Recently, we found that gentle mechanical skin stimulation inhibits the micturition reflex in anesthetized rats. However, the central mechanisms underlying this inhibition have not been determined. This study aimed to clarify the central neural mechanisms underlying this inhibitory effect. In urethane-anesthetized rats, cutaneous stimuli were applied for 1 min to the skin of the perineum using an elastic polymer roller with a smooth, soft surface. Inhibition of rhythmic micturition contractions by perineal stimulation was abolished by naloxone, an antagonist of opioidergic receptors, administered into the intrathecal space of the lumbosacral spinal cord at doses of 2–20 μg but was not affected by the same doses of naloxone administered into the subarachnoid space of the cisterna magna. Next, we examined whether perineal rolling stimulation inhibited the descending and ascending limbs of the micturition reflex. Perineal rolling stimulation inhibited bladder contractions induced by electrical stimulation of the pontine micturition center (PMC) or the descending tract of the micturition reflex pathway. It also inhibited the bladder distension-induced increase in the blood flow of the dorsal cord at L5–S1, reflecting the neural activity of this area, as well as pelvic afferent-evoked field potentials in the dorsal commissure at the lumbosacral level; these areas contain long ascending neurons to the PMC. Neuronal activities in this center were also inhibited by the rolling stimulation. These results suggest that the perineal rolling stimulation activates the spinal opioidergic system and inhibits both ascending and descending transmissions of the micturition reflex pathway in the spinal cord. These inhibitions would lead to the shutting down of positive feedback between the bladder and the PMC, resulting in inhibition of the micturition reflex. Based on the central neural mechanisms we show here, gentle perineal stimulation may be applicable to several different types of overactive bladder.
Collapse
Affiliation(s)
- Harumi Hotta
- Department of Autonomic Neuroscience, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
- * E-mail:
| | - Nobuhiro Watanabe
- Department of Autonomic Neuroscience, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| |
Collapse
|
4
|
Abstract
This article summarizes anatomical, neurophysiological, pharmacological, and brain imaging studies in humans and animals that have provided insights into the neural circuitry and neurotransmitter mechanisms controlling the lower urinary tract. The functions of the lower urinary tract to store and periodically eliminate urine are regulated by a complex neural control system in the brain, spinal cord, and peripheral autonomic ganglia that coordinates the activity of smooth and striated muscles of the bladder and urethral outlet. The neural control of micturition is organized as a hierarchical system in which spinal storage mechanisms are in turn regulated by circuitry in the rostral brain stem that initiates reflex voiding. Input from the forebrain triggers voluntary voiding by modulating the brain stem circuitry. Many neural circuits controlling the lower urinary tract exhibit switch-like patterns of activity that turn on and off in an all-or-none manner. The major component of the micturition switching circuit is a spinobulbospinal parasympathetic reflex pathway that has essential connections in the periaqueductal gray and pontine micturition center. A computer model of this circuit that mimics the switching functions of the bladder and urethra at the onset of micturition is described. Micturition occurs involuntarily in infants and young children until the age of 3 to 5 years, after which it is regulated voluntarily. Diseases or injuries of the nervous system in adults can cause the re-emergence of involuntary micturition, leading to urinary incontinence. Neuroplasticity underlying these developmental and pathological changes in voiding function is discussed.
Collapse
Affiliation(s)
- William C. de Groat
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, School of Medicine Pittsburgh, Pennsylvania
| | - Derek Griffiths
- Department of Medicine (Geriatrics), University of Pittsburgh, School of Medicine Pittsburgh, Pennsylvania
| | - Naoki Yoshimura
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, School of Medicine Pittsburgh, Pennsylvania
- Department of Urology, University of Pittsburgh, School of Medicine Pittsburgh, Pennsylvania
| |
Collapse
|
5
|
Xiang HB, Zhu WZ, Guan XH, Ye DW. Possible mechanism of deep brain stimulation for pedunculopontine nucleus-induced urinary incontinence: a virally mediated transsynaptic tracing study in a transgenic mouse model. Acta Neurochir (Wien) 2013; 155:1667-9. [PMID: 23657710 DOI: 10.1007/s00701-013-1743-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 04/23/2013] [Indexed: 01/23/2023]
|
6
|
Guo YX, Li DP, Chen SR, Pan HL. Distinct intrinsic and synaptic properties of pre-sympathetic and pre-parasympathetic output neurons in Barrington's nucleus. J Neurochem 2013; 126:338-48. [PMID: 23647148 DOI: 10.1111/jnc.12290] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 04/24/2013] [Accepted: 04/29/2013] [Indexed: 11/26/2022]
Abstract
Barrington's nucleus (BN), commonly known as the pontine micturition center, controls micturition and other visceral functions through projections to the spinal cord. In this study, we developed a rat brain slice preparation to determine the intrinsic and synaptic mechanisms regulating pre-sympathetic output (PSO) and pre-parasympathetic output (PPO) neurons in the BN using patch-clamp recordings. The PSO and PPO neurons were retrogradely labeled by injecting fluorescent tracers into the intermediolateral region of the spinal cord at T13-L1 and S1-S2 levels, respectively. There were significantly more PPO than PSO neurons within the BN. The basal activity and membrane potential were significantly lower in PPO than in PSO neurons, and A-type K(+) currents were significantly larger in PPO than in PSO neurons. Blocking A-type K(+) channels increased the excitability more in PPO than in PSO neurons. Stimulting μ-opioid receptors inhibited firing in both PPO and PSO neurons. The glutamatergic EPSC frequency was much lower, whereas the glycinergic IPSC frequency was much higher, in PPO than in PSO neurons. Although blocking GABAA receptors increased the excitability of both PSO and PPO neurons, blocking glycine receptors increased the firing activity of PPO neurons only. Furthermore, blocking ionotropic glutamate receptors decreased the excitability of PSO neurons but paradoxically increased the firing activity of PPO neurons by reducing glycinergic input. Our findings indicate that the membrane and synaptic properties of PSO and PPO neurons in the BN are distinctly different. This information improves our understanding of the neural circuitry and central mechanisms regulating the bladder and other visceral organs.
Collapse
Affiliation(s)
- Yue-Xian Guo
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, Houston, Texas 77030-4009, USA
| | | | | | | |
Collapse
|
7
|
Polysynaptic connections between Barrington's nucleus and sacral preganglionic neurons. Neurosci Res 2013; 75:150-6. [DOI: 10.1016/j.neures.2012.11.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Revised: 11/12/2012] [Accepted: 11/29/2012] [Indexed: 01/23/2023]
|
8
|
de Groat WC, Wickens C. Organization of the neural switching circuitry underlying reflex micturition. Acta Physiol (Oxf) 2013; 207:66-84. [PMID: 23033877 DOI: 10.1111/apha.12014] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 03/26/2012] [Accepted: 09/10/2012] [Indexed: 01/03/2023]
Abstract
The functions of the lower urinary tract to store and periodically eliminate urine are regulated by a complex neural control system in the brain and spinal cord that coordinates the activity of the bladder and urethral outlet. Experimental studies in animals indicate that urine storage is modulated by reflex mechanisms in the spinal cord, whereas voiding is mediated by a spinobulbospinal pathway passing through a coordination centre in the rostral brain stem. Many of the neural circuits controlling micturition exhibit switch-like patterns of activity that turn on and off in an all-or-none manner. This study summarizes the anatomy and physiology of the spinal and supraspinal micturition switching circuitry and describes a computer model of these circuits that mimics the switching functions of the bladder and urethra at the onset of micturition.
Collapse
Affiliation(s)
- W. C. de Groat
- Department of Pharmacology and Chemical Biology; University of Pittsburgh Medical School; Pittsburgh; PA; USA
| | - C. Wickens
- Department of Pharmacology and Chemical Biology; University of Pittsburgh Medical School; Pittsburgh; PA; USA
| |
Collapse
|
9
|
Jiang HH, Kokiko-Cochran ON, Li K, Balog B, Lin CY, Damaser MS, Lin V, Cheng JY, Lee YS. Bladder dysfunction changes from underactive to overactive after experimental traumatic brain injury. Exp Neurol 2012. [PMID: 23178579 DOI: 10.1016/j.expneurol.2012.11.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although bladder dysfunction is common after traumatic brain injury (TBI), few studies have investigated resultant bladder changes and the detailed relationship between TBI and bladder dysfunction. The goal of this study was to characterize the effects of TBI on bladder function in an animal model. Fluid-percussion injury was used to create an animal model with moderate TBI. Female Sprague-Dawley rats underwent TBI, sham TBI or were not manipulated (naïve). All rats underwent filling cystometry while bladder pressure and external urethral sphincter electromyograms were simultaneously recorded 1 day, 1 week, 2 weeks, and 1 month after injury. One day after injury, 70% of the animals in the TBI group and 29% of the animals in the sham TBI group showed no bursting activity during urination. Compared to naïve rats, bladder function was mainly altered 1 day and 1 week after sham TBI, suggesting the craniotomy procedure affected bladder function mostly in a temporary manner. Compared to either naïve or sham TBI, bladder weight was significantly increased 1 month after TBI and collagen in the bladder wall was increased. Bladder function in the TBI group went from atonic 1 day post-TBI to overactive 1 month post-TBI, suggesting that TBI significantly affected bladder function.
Collapse
Affiliation(s)
- Hai-Hong Jiang
- Department of Biomedical Engineering, Cleveland Clinic, Cleveland, OH, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Drake MJ, Fowler CJ, Griffiths D, Mayer E, Paton JFR, Birder L. Neural control of the lower urinary and gastrointestinal tracts: supraspinal CNS mechanisms. Neurourol Urodyn 2010; 29:119-27. [PMID: 20025025 DOI: 10.1002/nau.20841] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Normal urinary function is contingent upon a complex hierarchy of CNS regulation. Lower urinary tract afferents synapse in the dorsal horn of the spinal cord and ascend to the midbrain periaqueductal gray (PAG), with a separate nociception path to the thalamus. A spino-thalamo-cortical sensory pathway is present in some primates, including humans. In the brainstem, the pontine micturition center (PMC) is a convergence point of multiple influences, representing a co-ordinating center for voiding. Many PMC neurones have characteristics necessary to categorize the center as a pre-motor micturition nucleus. In the lateral pontine brainstem, a separate region has some characteristics to suggest a "continence center." Cerebral control determines that voiding is permitted if necessary, socially acceptable and in a safe setting. The frontal cortex is crucial for decision making in an emotional and social context. The anterior cingulate gyrus and insula co-ordinate processes of autonomic arousal and visceral sensation. The influence of these centers on the PMC is primarily mediated via the PAG, which also integrates bladder sensory information, thereby moderating voiding and storage of urine, and the transition between the two phases. The parabrachial nucleus in the pons is also important in behavioral motivation of waste evacuation. Lower urinary tract afferents can be modulated at multiple levels by corticolimbic centers, determining the interoception of physiological condition and the consequent emotional motor responses. Alterations in cognitive modulation, descending modulation, and hypervigilance are important in functional (symptom-based) clinical disorders.
Collapse
Affiliation(s)
- M J Drake
- Bristol Urological Institute, Southmead Hospital, Bristol, UK.
| | | | | | | | | | | |
Collapse
|
11
|
Tai C, Wang J, Jin T, Wang P, Kim SG, Roppolo JR, de Groat WC. Brain switch for reflex micturition control detected by FMRI in rats. J Neurophysiol 2009; 102:2719-30. [PMID: 19741099 DOI: 10.1152/jn.00700.2009] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The functions of the lower urinary tract are controlled by complex pathways in the brain that act like switching circuits to voluntarily or reflexly shift the activity of various pelvic organs (bladder, urethra, urethral sphincter, and pelvic floor muscles) from urine storage to micturition. In this study, functional magnetic resonance imaging (fMRI) was used to visualize the brain switching circuits controlling reflex micturition in anesthetized rats. The fMRI images confirmed the hypothesis based on previous neuroanatomical and neurophysiological studies that the brain stem switch for reflex micturition control involves both the periaqueductal gray (PAG) and the pontine micturition center (PMC). During storage, the PAG was activated by afferent input from the urinary bladder while the PMC was inactive. When bladder volume increased to the micturition threshold, the switch from storage to micturition was associated with PMC activation and enhanced PAG activity. A complex brain network that may regulate the brain stem micturition switch and control storage and voiding was also identified. Storage was accompanied by activation of the motor cortex, somatosensory cortex, cingulate cortex, retrosplenial cortex, thalamus, putamen, insula, and septal nucleus. On the other hand, micturition was associated with: 1) increased activity of the motor cortex, thalamus, and putamen; 2) a shift in the locus of activity in the cingulate and insula; and 3) the emergence of activity in the hypothalamus, substantia nigra, globus pallidus, hippocampus, and inferior colliculus. Understanding brain control of reflex micturition is important for elucidating the mechanisms underlying neurogenic bladder dysfunctions including frequency, urgency, and incontinence.
Collapse
Affiliation(s)
- Changfeng Tai
- Department of Urology, University of Pittsburgh, 700 Kaufmann Building, Pittsburgh, PA 15213, USA.
| | | | | | | | | | | | | |
Collapse
|
12
|
Abstract
Barrington's nucleus is a central component of the micturition circuit. This nucleus projects axons to the sacral parasympathetic nucleus, where preganglionic neurons innervating the urinary bladder are located. To clarify the functional role of this nucleus, the firing properties of Barrington's neurons that project axons to the spinal cord were examined. Based on these studies, a model begins to emerge that places Barrington's nucleus in the micturition pathway that is involved in increasing bladder pressure rapidly and strongly, while also maintaining high bladder pressure. In addition, Barrington's neurons are suggested to have another role, that is, increasing the probability of micturition contraction by activating a spinal excitatory pathway or disinhibiting a spinal inhibitory mechanism. In contrast to the excitatory role of Barrington's nucleus, this nucleus does not seem to trigger bladder relaxation.
Collapse
Affiliation(s)
- Mitsuyoshi Sasaki
- Department of Physiology, Tokyo Medical University, Tokyo 160, Japan.
| |
Collapse
|
13
|
Matsumoto M, Matsukawa K, Murata J, Ninomiya I. Cardiovascular and intravesical pressure responses during natural micturition in conscious rats. ACTA ACUST UNITED AC 2005; 54:567-74. [PMID: 15760489 DOI: 10.2170/jjphysiol.54.567] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Urinary bladder distension is known to influence the cardiovascular system under a pathophysiological condition such as spinal cord injury, hypertension, and arteriosclerosis. A reflex due to bladder distension and/or contraction is considered as one reason for the cardiovascular disturbance associated with micturition. However, it has remained unknown how much intravesical pressure (IVP) rises during micturition in daily life and to what extent mean arterial blood pressure (MAP) and heart rate (HR) respond at that time. To answer these questions, we attempted to examine the direct changes in IVP, MAP, and HR during natural micturition in freely moving conscious rats. IVP increased from the baseline value of 4 +/- 0.2 mmHg to 14 +/- 0.5 mmHg during natural micturition. Although MAP and HR began to increase before micturition, the increases in MAP and HR became significant 1-4 s before its onset. The peak increases in MAP and HR (7 +/- 0.8 mmHg and 14 +/- 3 beats/min, respectively) were delayed by 2 s from the peak IVP. Following an administration of xylocaine into the urinary bladder, the increases in MAP and HR during micturition were significantly blunted to 5 +/- 2 mmHg and 8 +/- 3 beats/min, although IVP increased the same as it did during micturition without xylocaine. Moreover, the relationship between IVP and MAP or HR during natural micturition resembled that between IVP and the vesico-cardiovascular reflex responses during isovolumic bladder contraction in anesthetized rats. Therefore it is concluded that natural micturition in freely moving conscious rats accompanies the significant cardiovascular responses despite a limited increase in intravesical pressure, to which a reflex from the urinary bladder may substantially contribute.
Collapse
Affiliation(s)
- Mutsuko Matsumoto
- Department of Physiology, Graduate School of Health Sciences, Hiroshima University, Minami-ku, Hiroshima 734-8551, Japan
| | | | | | | |
Collapse
|
14
|
Sasaki M. Properties of Barrington's neurones in cats: units that fire inversely with micturition contraction. Brain Res 2005; 1033:41-50. [PMID: 15680338 DOI: 10.1016/j.brainres.2004.11.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2004] [Indexed: 10/25/2022]
Abstract
Barrington's nucleus contains neurones that decrease their firing during micturition contraction, as well as neurones that increase their firing during this phase. These neurones are commonly termed inverse neurones and direct neurones, respectively. The aims of the present study were to determine whether inverse neurones send descending axons to the spinal cord and to clarify how these neurones regulate bladder contractility. Forty-five single neurones were recorded from the dorsolateral pontine tegmentum. Spinal-projecting neurones were identified by antidromic stimulation of the spinal cord. More than half of inverse neurones were located outside Barrington's nucleus. Only three were spinal-projecting neurones. The results were in marked contrast with direct neurones that we studied previously: the majority of them were located within Barrington's nucleus, and 56% were spinal-projecting neurones. The firing frequency of inverse neurones ranged between 6 and 37 Hz during the relaxation phase of the micturition contraction-relaxation rhythm. The firing of all neurones began to decrease within 8 s after the onset of micturition contraction. During micturition contraction, neurones displayed little firing, being virtually silent (n = 29) or displayed weak tonic firing (3-11 Hz; n = 16). All neurones began to increase their firing within 8 seconds after the onset of bladder relaxation. These results suggest that inverse neurones do not trigger bladder contraction or relaxation, despite the finding that a few of them send descending axons to the spinal cord. One possible role of the inverse neurone is to regulate firing activities of direct neurones in Barrington's nucleus.
Collapse
Affiliation(s)
- Mitsuyoshi Sasaki
- Department of Physiology, Tokyo Medical University, 6-1-1 Shinjuku, Tokyo 160, Japan.
| |
Collapse
|
15
|
Russo A, Monaco S, Romeo R, Pellitteri R, Stanzani S. Serotonergic collateralized projections from Barrington's nucleus to the medial preoptic area and lumbo-sacral spinal cord. Brain Res 2004; 1019:64-7. [PMID: 15306239 DOI: 10.1016/j.brainres.2004.03.080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/10/2004] [Indexed: 01/30/2023]
Abstract
In this study, we employed triple fluorescent labelling to reveal the distribution of the direct serotonergic neurons within Barrington's nucleus (BN) that supply branching collateral input to the medial preoptic area (MPA) and to the lumbo-sacral spinal cord (LSC). Immunocytochemical detection of the monoclonal antibody raised against serotonin was used for identification of the neurons. The projections were defined by injections of two retrograde tracers: fluoro gold and rhodamine in the MPA and LSC, respectively. The aim of this study is to identify the direct projections to BN and MPA and/or LSC. The present study confirms findings of others describing BN-LSC projections and extends previous findings by demonstrating an single or collateralized fibers with MPA, and serotonergic immunoreactive fibers.
Collapse
Affiliation(s)
- Antonella Russo
- Department of Physiological Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy.
| | | | | | | | | |
Collapse
|
16
|
Sasaki M. Feed-forward and feedback regulation of bladder contractility by Barrington's nucleus in cats. J Physiol 2004; 557:287-305. [PMID: 15047771 PMCID: PMC1665040 DOI: 10.1113/jphysiol.2003.059352] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2003] [Accepted: 03/12/2004] [Indexed: 11/08/2022] Open
Abstract
The purpose of the present study was to clarify how Barrington's nucleus regulates bladder contractility. Single neurones that discharge at higher rates during micturition contraction were recorded from Barrington's nucleus. Spinal-projecting neurones were identified by antidromic stimulation of the spinal cord. Seventy-six spinal-projecting neurones were classified into four types based on the firing patterns displayed during the relaxation phase of the micturition contraction-relaxation rhythm: (1) ramp-tonic neurones displayed a ramp increase in firing throughout the relaxation phase, (2) ramp-silent neurones were silent initially during the relaxation phase and displayed a ramp increase later, (3) flat-tonic neurones fired constantly, and (4) flat-silent neurones displayed little firing, being virtually silent throughout relaxation. During the relaxation phase, discharge volleys from Barrington's nucleus to sacral neurones were estimated to increase exponentially as micturition contraction approached. Twenty-two neurones increased firing even further within 3 s of micturition contraction, suggesting that they are involved in the final stages of initiation of micturition contraction. During micturition contraction, 18 neurones (of which 14 belonged to the ramp-silent class) displayed maximal firing rates before maximal bladder pressures were reached; firing gradually decreased during micturition contraction. Thirty-nine neurones (of which 25 belonged to the ramp-tonic class) displayed constant firing during micturition contraction. This suggests that ramp-silent neurones might be involved in increasing bladder pressure rapidly and strongly via feed-forward regulation, while ramp-tonic neurones might be involved in maintaining high bladder pressure via positive feedback from the bladder afferents. Sixty neurones continued to fire for 1-8 s after the onset of bladder relaxation, suggesting that Barrington's nucleus does not trigger bladder relaxation.
Collapse
Affiliation(s)
- Mitsuyoshi Sasaki
- Department of Physiology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo 160, Japan.
| |
Collapse
|