scholarly journals Brainstem control of urethral sphincter relaxation and scent marking behavior

2018 ◽  
Author(s):  
Jason Keller ◽  
Jingyi Chen ◽  
Sierra Simpson ◽  
Eric Hou-Jen Wang ◽  
Varoth Lilascharoen ◽  
...  
Keyword(s):  
Striated Muscle ◽  
Scent Marking ◽  
Voluntary Control ◽  
Bladder Pressure ◽  
Urethral Sphincter ◽  
External Urethral Sphincter ◽  
Full Bladder ◽  
Bladder Contraction ◽  
Decisive Action ◽  
Fast Control

Urination may occur either reflexively in response to a full bladder or deliberately irrespective of immediate need. Voluntary control is desired because it ensures that waste is expelled when consciously desired and socially appropriate1,2. Urine release requires two primary components: bladder pressure and urethral relaxation1–3. Although the bladder contracts during urination, its slow smooth muscle is not under direct voluntary control and its contraction alone is not sufficient for voiding. The decisive action of urination is at the urethral sphincter, where striated muscle permits fast control. This sphincter is normally constricted, but relaxes to enable urine flow. Barrington’s nucleus (Bar, or pontine micturition center) in the brainstem is known to be essential for the switch from urine storage to elimination4–7, and a subset of Bar neurons expressing corticotropin releasing hormone (BarCRH) have recently been shown to promote bladder contraction8–10. However, Bar neurons that relax the urethral sphincter to enable urination behavior have not been identified. Here we describe novel brainstem neurons that control the external urethral sphincter. We find that scent marking behavior in male mice depends upon a subpopulation of spatially clustered Bar neurons that express high levels of estrogen receptor 1 (BarESR1). These neurons are glutamatergic, project to urinary nuclei in the spinal cord with a bias towards sphincter-inhibiting interneurons, and their activity correlates with natural urination. Optogenetic stimulation of BarESR1 neurons rapidly initiates sphincter bursting and efficient voiding in absence of sensory cues in anesthetized and behaving animals. Conversely, inhibiting the activity of these neurons prevents olfactory cues from promoting scent marking behavior. The identification of BarESR1 cells provides an expanded model for the supraspinal control of urination and its dysfunction.

Sexually dimorphic micturition in rats: relationship of perineal muscle activity to voiding pattern

2005 ◽  
Vol 289 (5) ◽  
pp. R1307-R1318 ◽  
Author(s):  
Yolanda Cruz ◽  
John W. Downie
Keyword(s):  
Muscle Activity ◽  
High Frequency ◽  
Striated Muscle ◽  
Female Rats ◽  
Bladder Pressure ◽  
Sexually Dimorphic ◽  
External Urethral Sphincter ◽  
Motor Branch ◽  
Male And Female Rats ◽  
Bladder Contraction

In the present study we examined the possibility that striated muscle activity may underlie sexually dimorphic micturition in rats. Micturition dynamics, the gross anatomy of the external urethral sphincter, and the participation of the striated perineal muscles in micturition were compared in urethane-anesthetized adult male and female rats. Bladder contraction characteristics, particularly the magnitude of bladder high-frequency pressure waves during voiding, differed between sexes. Dissections indicated that the sphincter was more extensive and thicker in males than in females. Electromyography showed that in both sexes the sphincter discharged in bursts that correlated with the rising phase of high-frequency bladder pressure oscillations. Regional differences in discharge pattern were seen in the sphincters of males, with the proximal part of the sphincter showing components activated during bladder filling. Bulbospongiosus, ischiocavernosus, and cremaster muscles also were activated during bladder contraction in males. In both sexes transection of the motor branch of the lumbosacral plexus eliminated the bladder high-frequency oscillations and reduced voided volume. Neurectomy did not affect bladder pressure but reduced voiding efficiency by 45% in males. In females the bladder pressure was dramatically decreased, but voiding efficiency only decreased by 24%. Our findings suggest that, in rats, striated perineal muscles contribute to the sexually dimorphic micturition. Activity of the dimorphic perineal muscles may regulate genital and urinary urethra expulsive functions, helping to expel seminal plug and fluids through the long urethra in the male.

scholarly journals Pelvic Floor Muscles and the External Urethral Sphincter Have Different Responses to Applied Bladder Pressure During Continence

Urology ◽  
2010 ◽  
Vol 75 (6) ◽  
pp. 1515.e1-1515.e7 ◽  
Author(s):  
Hai-Hong Jiang ◽  
Levilester B. Salcedo ◽  
Bo Song ◽  
Margot S. Damaser
Keyword(s):  
Pelvic Floor ◽  
Pelvic Floor Muscles ◽  
Bladder Pressure ◽  
Urethral Sphincter ◽  
External Urethral Sphincter

A comparative study of voiding in rat and guinea pig: simultaneous measurement of flow rate and pressure

1995 ◽  
Vol 269 (1) ◽  
pp. R98-R103 ◽  
Author(s):  
E. Van Asselt ◽  
J. Groen ◽  
R. Van Mastrigt
Keyword(s):  
Guinea Pig ◽  
Flow Rate ◽  
High Frequency ◽  
Bladder Pressure ◽  
Male Rat ◽  
Intermittent Flow ◽  
Intravesical Pressure ◽  
External Urethral Sphincter ◽  
High Frequency Oscillations ◽  
Bladder Contraction

In this study, the voiding phase of the micturition cycle in the anesthetized rat and guinea pig is analyzed. In both animals, voiding is characterized by an increase in intravesical pressure and then a decrease, which is accompanied by flow through the urethra and emission of urine. An ultrasonic flow probe was used in both species to measure the flow rate in relation to the intravesical pressure. In the (male) rat, so-called high-frequency oscillations are superimposed on the decreasing bladder pressure. These oscillations do not occur in the guinea pig. It is concluded that the high-frequency oscillations are caused by intermittent flow and not by variations in the bladder contraction. The intermittent flow most likely is caused by the relaxation and contraction of the external urethral sphincter and may have a function in territory marking. In our view, it is not likely that the oscillations enhance bladder emptying, as has been suggested in the literature.

LOCAL INJECTION OF CONOPEPTIDE MI INHIBITS STRIATED MUSCLE OF EXTERNAL URETHRAL SPHINCTER IN A DOSE DEPENDENT FASHION

1999 ◽  
pp. 47
Author(s):  
Matthew O. Fraser ◽  
Michael B. Chancellor ◽  
William C. de Groat ◽  
Li-Ming Zhou ◽  
Jacob S. Nielsen ◽  
...  
Keyword(s):  
Striated Muscle ◽  
Local Injection ◽  
Urethral Sphincter ◽  
External Urethral Sphincter ◽  
Dose Dependent Fashion ◽  
Dose Dependent

Volume-evoked micturition reflex is mediated by the ventrolateral periaqueductal gray in anesthetized rats

1998 ◽  
Vol 275 (6) ◽  
pp. R2049-R2055 ◽  
Author(s):  
Shinobu Matsuura ◽  
Gary V. Allen ◽  
John W. Downie
Keyword(s):  
Blood Pressure ◽  
Cobalt Chloride ◽  
Periaqueductal Gray ◽  
Bladder Pressure ◽  
Electromyographic Activity ◽  
Urethral Sphincter ◽  
External Urethral Sphincter ◽  
Micturition Reflex ◽  
Arterial Blood ◽  
Synaptic Neurotransmission

The central pathway of the micturition reflex in the rat was investigated functionally by acute blockade of synaptic neurotransmission using microinjection of cobalt chloride into the periaqueductal gray or pontine tegmental region. In 27 urethan-anesthetized (1.2 g/kg ip) rats, the bladder pressure response to continuous infusion of the bladder with saline (0.1–0.25 ml/min) was assessed. Electromyographic activity of external urethral sphincter and arterial blood pressure were also monitored. Bladder contractions and external urethral sphincter activity were reversibly attenuated after unilateral or bilateral stereotaxic injections of 10 mM cobalt chloride into the caudal (bregma −7.80 to −8.80) ventrolateral periaqueductal gray as well as into Barrington’s nucleus. Blood pressure was not affected by injection into either area. The results demonstrate that the caudal ventrolateral periaqueductal gray, in addition to Barrington’s nucleus, is a critical part of the long-routed micturition reflex circuitry in the anesthetized rat.

External urethral sphincter motor unit recruitment patterns during micturition in the spinally intact and transected adult rat

2012 ◽  
Vol 108 (9) ◽  
pp. 2554-2567 ◽  
Author(s):  
Stephen C. D'Amico ◽  
William F. Collins
Keyword(s):  
Motor Unit ◽  
Frequency Modulation ◽  
Bladder Pressure ◽  
High Threshold ◽  
Urethral Sphincter ◽  
External Urethral Sphincter ◽  
Adult Rat ◽  
Active Contraction ◽  
Low Threshold ◽  
Intact Rats

In the rat, external urethral sphincter (EUS) activation during micturition consists of three sequential phases: 1) an increase in tonic EUS activity during passive filling and active contraction of the bladder (guarding reflex), 2) synchronized phasic activity (EUS bursting) associated with voiding, and 3) sustained tonic EUS activity that persists after bladder contraction. These phases are perturbed following spinal cord injury. The purpose of the present study was to characterize individual EUS motor unit (MU) patterns during micturition in the spinally intact and transected adult rat. EUS MU activity was recorded from either the L5 or L6 ventral root (intact) or EUS muscle (transected) during continuous flow cystometry in urethane-anesthetized adult female Sprague-Dawley rats. With the use of bladder pressure threshold and timing of activation, four distinct patterns of EUS MU activity were identified in the intact rat: low threshold sustained, medium/high threshold sustained, medium/high threshold not sustained, and burst only. In general, these MUs displayed little frequency modulation during active contraction, generated high-frequency bursts of action potentials during EUS bursting, and varied in terms of the duration of sustained tonic activity. In contrast, three general patterns of EUS MU activity were identified in the transected rat: low threshold, medium threshold, and high threshold. These MUs exhibited considerable frequency modulation during active contraction of the bladder, no bursting behavior and little to no sustained firing. The prominent frequency modulation of EUS MUs is likely due to the enhanced guarding reflex seen in EUS whole muscle electromyogram recordings in transected rats (D'Amico SC, Schuster IP, Collins WF 3rd. Exp Neurol 228: 59–68, 2011). In addition, EUS MU recruitment in transected rats more closely followed predictions by the size principle than in intact rats. This may reflect the influence of local synaptic circuits or intrinsic properties of EUS motoneurons that are active in intact rats but attenuated or absent in transected rats.

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