scholarly journals External Urethral Sphincter Motoneuron Properties in Adult Female Rats Studied In Vitro

2010 ◽  
Vol 104 (3) ◽  
pp. 1286-1300 ◽  
Author(s):  
Jonathan S. Carp ◽  
Ann M. Tennissen ◽  
Jennifer E. Liebschutz ◽  
Xiang Yang Chen ◽  
Jonathan R. Wolpaw
Keyword(s):  
Adult Female ◽  
Average Rate ◽  
Physiological Role ◽  
Input Resistance ◽  
Female Rats ◽  
Repetitive Firing ◽  
Urethral Sphincter ◽  
External Urethral Sphincter ◽  
Opposite Pattern

The external urethral sphincter (EUS) muscle plays a crucial role in lower urinary tract function: its activation helps maintain continence, whereas its relaxation contributes to micturition. To determine how the intrinsic properties of its motoneurons contribute to its physiological function, we have obtained intracellular current-clamp recordings from 49 EUS motoneurons in acutely isolated spinal cord slices from adult female rats. In all, 45% of EUS motoneurons fired spontaneously and steadily (average rate = 12–27 pulses/s). EUS motoneurons were highly excitable, having lower rheobase, higher input resistance, and smaller threshold depolarization than those of rat hindlimb motoneurons recorded in vitro. Correlations between these properties and afterhyperpolarization half-decay time are consistent with EUS motoneurons having characteristics of both fast and slow motor unit types. EUS motoneurons with a slow-like spectrum of properties exhibited spontaneous firing more often than those with fast-like characteristics. During triangular current ramp-induced repetitive firing, recruitment typically occurred at lower current levels than those at derecruitment, although the opposite pattern occurred in 10% of EUS motoneurons. This percentage was likely underestimated due to firing rate adaptation. These findings are consistent with the presence of a basal level of persistent inward current (PIC) in at least some EUS motoneurons. The low EUS motoneuron current and voltage thresholds make them readily recruitable, rendering them well suited to their physiological role in continence. The expression of firing behaviors consistent with PIC activation in this highly reduced preparation raises the possibility that in the intact animal, PICs contribute to urinary function not only through neuromodulator-dependent but also through neuromodulator-independent mechanisms.

CORTICOSTEROID-UMSATZ UND CORTICOSTEROID-PRODUKTION BEI RATTEN UNTER DER BEHANDLUNG MIT ANABOLEN STEROIDEN

1965 ◽  
Vol 48 (2) ◽  
pp. 263-271 ◽  
Author(s):  
Herbert Schriefers ◽  
Gerlinde Scharlau ◽  
Franzis Pohl
Keyword(s):  
Production Rate ◽  
Adult Female ◽  
Anabolic Steroids ◽  
Reduction Rate ◽  
Female Rats ◽  
Adrenal Weight ◽  
Hydrogenase Activity ◽  
Anabolic Effect ◽  
Liver Slices

ABSTRACT After the administration of anabolic steroids to adult female rats in daily doses of 1 mg per animal for 14 days, the following parameters were investigated: the rate of the Δ4-5α-hydrogenase-catalyzed cortisone reduction in liver slices and microsomal fractions, the adrenal weight and the in vitro corticosterone production rate. Among the steroids tested, only 17α-methyl-testosterone and 17α-ethyl-19-nor-testosterone were effective in lowering significantly cortisone reduction rate by liver slices with concomitant decreases in microsomal Δ4-5α-hydrogenase-activity. Testosterone, 19-nor-testosterone, 17α-ethinyl-19-nor-testosterone, 17α-methyl-17β-hydroxy-androsta-1,4-dien-3-one and 1-methyl-17β-hydroxy-androst-1-en-3-one were ineffective or only slightly effective. Adrenal weight and absolute corticosterone production rate (μg/60 min per animal) were decreased after treatment with 17α-methyl-testosterone, 17α-ethyl-19-nor-testosterone and 1-methyl-17β-hydroxy-androst-1-en-3-one. Corticosterone production was decreased with 17α-ethinyl-19-nor-testosterone in spite of an unchanged adrenal weight. The relative corticosterone production rate (μg/60 min · 100 mg adrenal) was in any cases unaffected. According to these results there exists – with the exception of 17α-ethinyl-19-nor-testosterone – a strict parallelism between corticosteroid turnover and corticosterone production rate: unchanged turnover is correlated with unchanged corticosterone production rate, while a decreased turnover is correlated with decreased adrenal activity. The protein-anabolic effect of certain anabolic steroids may be partly due to an anti-catabolic action of these compounds resulting from a decreased corticosteroid inactivation and production rate. Possible mechanisms by which anabolic steroids may affect corticosteroid-balance are discussed.

METABOLISM OF 20β-HYDROXY-4-PREGNEN-3-ONE IN UTERINE TISSUE OF NON-PREGNANT RATS IN VITRO

1976 ◽  
Vol 83 (3) ◽  
pp. 604-620 ◽  
Author(s):  
B. P. Lisboa ◽  
M. Holtermann
Keyword(s):  
Biological Activity ◽  
Adult Female ◽  
Female Rats ◽  
Uterine Tissue ◽  
Rat Uterus ◽  
Adult Rats ◽  
Pregnant Rats ◽  
Progesterone Metabolites ◽  
Ovariectomized Adult Rats

ABSTRACT In vitro experiments carried out with uterus preparations of ovariectomized adult rats indicate the presence in this tissue of a 20β-hydroxysteroid-oxidoreductase which catalyzes the conversion of 20β-hydroxy-4-pregnen-3-one to progesterone. Since a hepatic 20β-hydroxysteroid-oxidoreductase is absent in adult female rats, the myometrial enzyme can be responsible for the biological activity of 20β-hydroxy-4-pregnen-3-one in these animals. Besides progesterone five metabolites were isolated and identified after incubation of [4-14C]20β-hydroxy-4-pregnen-3-one with uterine tissue: 20β-hydroxy-5α-pregnan-3-one, 20β-hydroxy-5β-pregnan-3-one, 5α-pregnane-3α,20β-diol, 4-pregnene-3α,20β-diol and 4-pregnene-3β,20β-diol. The conversion of 20β-hydroxy-4-pregnen-3-one to progesterone permits us to regard all five steroids isolated as progesterone metabolites in the rat uterus. 20β-hydroxy-5β-pregnan-3-one is the first C21-metabolite with a 5β(H)-configuration isolated in the rat uterus, which indicates the presence of 5β-reductase in this tissue.

Morphological and functional response to injury to the external urethral sphincter - similarities and differences between male and female rats

2014 ◽  
Vol 35 (3) ◽  
pp. 371-376
Author(s):  
Scheila F. C. Nascimento ◽  
Ana Paula S. Bispo ◽  
Katia Ramos Leite ◽  
Helio Plapler ◽  
Claudius Füllhase ◽  
...  
Keyword(s):  
Functional Response ◽  
Female Rats ◽  
Urethral Sphincter ◽  
External Urethral Sphincter ◽  
Male And Female ◽  
Male And Female Rats ◽  
Similarities And Differences

Activation of the external urethral sphincter central pattern generator by a 5-HT1A receptor agonist in rats with chronic spinal cord injury

2007 ◽  
Vol 292 (4) ◽  
pp. R1699-R1706 ◽  
Author(s):  
Paul C. Dolber ◽  
Baojun Gu ◽  
Xiaoyang Zhang ◽  
Matthew O. Fraser ◽  
Karl B. Thor ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Receptor Agonist ◽  
Bladder Capacity ◽  
Female Rats ◽  
Residual Volume ◽  
Urethral Sphincter ◽  
External Urethral Sphincter ◽  
Chronic Spinal Cord Injury ◽  
Cord Injury

We recently demonstrated that treatment with the 5-HT1A/7 receptor agonist [(R)-(+)-8-hydroxy-2-di-n-propylamino]tetralin (8-OH-DPAT) increases bladder capacity in chloralose-anesthetized female cats with chronic spinal cord injury. In the current study, we investigated the effects of 8-OH-DPAT on bladder capacity and external urethral sphincter (EUS) activity in urethane-anesthetized female rats (initial body mass 175–200 g) with chronic spinal cord injury (transsection at T10). Cystometric study took place 8–12 wk posttranssection. Intravesical pressure was monitored in urethane-anesthetized rats with a transvesical catheter, and EUS activity was assessed electromyographically. Spinal cord injury disrupts phasic activity of the EUS, resulting in decreased voiding efficiency and increased residual volume. 8-OH-DPAT induced a dose-dependent decrease in bladder capacity (the opposite of its effect in chronic spinal cord-injured cats) with an increase in micturition volume and decrease in residual volume resulting from improvement in voiding efficiency. The unexpected improvement in voiding efficiency can be explained by the 8-OH-DPAT-induced emergence of phasic EUS relaxation. Phasic EUS relaxation was also altered by 8-OH-DPAT in spinally intact rats, whereas the 5-HT1A receptor antagonist N-tert-butyl-3-[4-(2-methoxyphenyl)-piperazin-1-yl]-2-phenylpropanamide (WAY-100635), on its own, was without effect. It remains to be determined when phasic relaxation is restored after spinal cord injury, and indeed whether it is ever truly lost or is only temporarily separated from excitatory input.

Effects of Ghrelin upon Gonadotropin-Releasing Hormone and Gonadotropin Secretion in Adult Female Rats: In vivo and in vitro Studies

2005 ◽  
Vol 82 (5-6) ◽  
pp. 245-255 ◽  
Author(s):  
Rafael Fernández-Fernández ◽  
Manuel Tena-Sempere ◽  
Víctor M. Navarro ◽  
María L. Barreiro ◽  
Juan M. Castellano ◽  
...  
Keyword(s):  
Adult Female ◽  
Gonadotropin Releasing Hormone ◽  
In Vitro Studies ◽  
Female Rats ◽  
Gonadotropin Secretion ◽  
Releasing Hormone

scholarly journals Rat Mesenchymal Stem Cell Secretome Promotes Elastogenesis and Facilitates Recovery from Simulated Childbirth Injury

2014 ◽  
Vol 23 (11) ◽  
pp. 1395-1406 ◽  
Author(s):  
Charuspong Dissaranan ◽  
Michelle A. Cruz ◽  
Matthew J. Kiedrowski ◽  
Brian M. Balog ◽  
Bradley C. Gill ◽  
...  
Keyword(s):  
Female Rats ◽  
Urethral Sphincter ◽  
Leak Point Pressure ◽  
External Urethral Sphincter ◽  
Paracrine Factors ◽  
Pelvic Organs ◽  
Point Pressure ◽  
Urethral Smooth Muscle ◽  
And Function ◽  
Vaginal Distension

Vaginal delivery is a risk factor for stress urinary incontinence (SUI). Mesenchymal stem cells (MSCs) home to injured organs and can facilitate repair. The goal of this study was to determine if MSCs home to pelvic organs after simulated childbirth injury and facilitate recovery from SUI via paracrine factors. Three experiments were performed. Eighteen female rats received vaginal distension (VD) or sham VD and labeled intravenous (IV) MSCs to investigate if MSCs home to the pelvic organs. Whole-organ imaging and immunofluorescence were performed 1 week later. Thirty-four female rats received VD and IV MSCs, VD and IV saline, or sham VD and IV saline to investigate if MSCs accelerate recovery of continence. Twenty-nine female rats received VD and periurethral concentrated conditioned media (CCM), VD and periurethral control media, or sham VD and periurethral control media to investigate if factors secreted by MSCs accelerate recovery from VD. Urethral histology and function were assessed 1 week later. Significantly more MSCs were observed in the urethra, vagina, and spleen after VD compared to sham VD. Continence as measured by leak point pressure (LPP) was significantly reduced after VD in rats treated with saline or control media compared to sham VD but not in those given MSCs or CCM. External urethral sphincter (EUS) function as measured by electromyography (EMG) was not improved with MSCs or CCM. Rats treated with MSCs or CCM demonstrated an increase in elastin fibers near the EUS and urethral smooth muscle more similar to that of sham-injured animals than rats treated with saline or control media. MSCs homed to the urethra and vagina and facilitated recovery of continence most likely via secretion of paracrine factors. Both MSCs and CCM have promise as novel noninvasive therapies for SUI.

Pituitary receptors for LH-releasing hormone (LHRH) and responsiveness to LHRH in adult female rats after neonatal monosodium l-glutamate treatment

1985 ◽  
Vol 107 (1) ◽  
pp. 9-13 ◽  
Author(s):  
S. E. Inkster ◽  
R. N. Clayton ◽  
S. A. Whitehead
Keyword(s):  
Adult Female ◽  
Female Rats ◽  
Serum Prolactin ◽  
Female Rat ◽  
Releasing Hormone ◽  
Old Rats ◽  
Lh Releasing Hormone ◽  
Ovarian Cyclicity ◽  
Pituitary Receptors

ABSTRACT The effects of neonatal monosodium l-glutamate (MSG) treatment on pituitary responsiveness to LH-releasing hormone (LHRH) and on pituitary LHRH receptors have been investigated in the intact adult female rat. Three- to four-month-old rats treated with MSG (4 mg/g body wt) on days 2, 4, 6, 8 and 10 after birth had significantly reduced ovarian and pituitary weights, showed an absence or disruption of ovarian cyclicity after puberty, and had significantly higher concentrations of serum prolactin despite normal levels of LH. In-vitro pituitary LH responses to LHRH were in the normal range for one group of treated animals whilst in a second group the LH responses were markedly enhanced. In contrast, the total number of pituitary LHRH receptors were significantly reduced in all MSG-treated animals showing that the increased pituitary responsiveness of MSG-treated animals is not attributable to an increase in pituitary LHRH receptors. J. Endocr. (1985) 107, 9–13

scholarly journals The GH secretagogues ipamorelin and GH-releasing peptide-6 increase bone mineral content in adult female rats

2000 ◽  
Vol 165 (3) ◽  
pp. 569-577 ◽  
Author(s):  
J Svensson ◽  
S Lall ◽  
SL Dickson ◽  
BA Bengtsson ◽  
J Romer ◽  
...  
Keyword(s):  
Body Weight ◽  
Bone Mineral Content ◽  
Bone Mineral ◽  
Adult Female ◽  
Mineral Content ◽  
Female Rats ◽  
Volumetric Bmd ◽  
Ash Weight

Growth hormone (GH) is of importance for normal bone remodelling. A recent clinical study demonstrated that MK-677, a member of a class of GH secretagogues (GHSs), increases serum concentrations of biochemical markers of bone formation and bone resorption. The aim of the present study was to investigate whether the GHSs, ipamorelin (IPA) and GH-releasing peptide-6 (GHRP-6), increase bone mineral content (BMC) in young adult female rats. Thirteen-week-old female Sprague-Dawley rats were given IPA (0.5 mg/kg per day; n=7), GHRP-6 (0.5 mg/kg per day; n=8), GH (3.5 mg/kg per day; n=7), or vehicle administered continuously s.c. via osmotic minipumps for 12 weeks. The animals were followed in vivo by dual X-ray absorptiometry (DXA) measurements every 4th week. After the animals were killed, femurs were analysed in vitro by mid-diaphyseal peripheral quantitative computed tomography (pQCT) scans. After this, excised femurs and vertebrae L6 were analysed by the use of Archimedes' principle and by determinations of ash weights. All treatments increased body weight and total tibial and vertebral BMC measured by DXA in vivo compared with vehicle-treated controls. However, total BMC corrected for the increase in body weight (total BMC:body weight ratio) was unaffected. Tibial area bone mineral density (BMD, BMC/area) was increased, but total and vertebral area BMDs were unchanged. The pQCT measurements in vitro revealed that the increase in the cortical BMC was due to an increased cross-sectional bone area, whereas the cortical volumetric BMD was unchanged. Femur and vertebra L6 volumes were increased but no effect was seen on the volumetric BMDs as measured by Archimedes' principle. Ash weight was increased by all treatments, but the mineral concentration was unchanged. We conclude that treatment of adult female rats with the GHSs ipamorelin and GHRP-6 increases BMC as measured by DXA in vivo. The results of in vitro measurements using pQCT and Archimedes' principle, in addition to ash weight determinations, show that the increases in cortical and total BMC were due to an increased growth of the bones with increased bone dimensions, whereas the volumetric BMD was unchanged.

scholarly journals Altered vascular contractility in adult female rats with hypertension programmed by prenatal glucocorticoid exposure

2006 ◽  
Vol 188 (3) ◽  
pp. 435-442 ◽  
Author(s):  
P W F Hadoke ◽  
R S Lindsay ◽  
J R Seckl ◽  
B R Walker ◽  
C J Kenyon
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Adult Female ◽  
Vascular Function ◽  
Mesenteric Arteries ◽  
Female Rats ◽  
Control Group ◽  
Pregnant Rats ◽  
Vascular Contractility

Excessive exposure to glucocorticoids during gestation reduces birth weight and induces permanent hypertension in adulthood. The mechanisms underlying this programmed elevation of blood pressure have not been established. We hypothesised that prenatal glucocorticoid exposure may lead to vascular dysfunction in adulthood. Pregnant rats received dexamethasone (Dex) (100 μg/kg, s.c.) or vehicle (control) daily throughout pregnancy. Blood pressure was elevated (students t-test, unpaired; P < 0.05) in adult female offspring (aged 12–16 weeks) of Dex-treated mothers (148.0 ± 3.6 mmHg, n=10) compared with the control group (138.0 ± 2.5 mmHg, n=8). Vascular responsiveness in aortae and mesenteric arteries was differentially affected by prenatal Dex: aortae were less responsive to angiotensin II, whereas mesenteric arteries were more responsive to norepinephrine, vasopressin and potassium (mesenteric arteries respond poorly to angiotensin II in vitro). Acetylcholine-mediated, endothelium-dependent relaxation was similar in both groups. Prenatal exposure to Dex had no effect on blood pressure or aldosterone response to acute (15 min, i.v.) infusion of angiotensin II (75 ng/kg per min). In contrast, chronic (2-week, s.c.) infusion of angiotensin II (100 ng/kg per min) produced a greater elevation (P < 0.05) of blood pressure in Dex-treated rats (150.0 ± 3.6 mmHg) than in controls (135.3 ± 5.4 mmHg), and aldosterone levels were higher in Dex-treated animals. There was no angiotensin II-induced medial hypertrophy/hyperplasia in mesenteric arteries from Dex-treated rats. These results indicate that vascular function is altered in a region-specific manner in rats with glucocorticoid-programmed hypertension. Despite a striking increase in mesenteric artery contraction in Dex-treated rats, in vivo studies suggest that abnormalities of the renin-angiotensin-aldosterone system, rather than enhanced vascular contractility, may be responsible for the elevation of blood pressure in these animals.

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