Effect of thyroxine on the contractile responses of the vas deferens to prostaglandin E2

The effects of prostaglandin E2 (PGE2) on the contractile activity of thyroidectomized and thyroxine-treated albino rats were studied in vitro. Thyroidectomy totally inhibited the contractile response of the vas deferens to PGE2. Thyroxine treatment, on the other hand, significantly (P < .001) potentiated the response of vasa deferentia to PGE2, when compared to controls. It is suggested that thyroid hormones play a role in the contractile response of the vas deferens to PGE2.     

Vasography: effect of various agents on vas deferens patency

Vasography is a common diagnostic procedure utilized in evaluating the male genital tract for causes of azoospermia, for evaluation of persistent perineal pain and seminal vesiculitis, and recently used in the staging of prostate cancer. In order to evaluate the effects of injectable agents on the healthy vas deferens, 7 groups of 10 rats had the left vas deferens injected by vasopuncture with saline, 4 contrast agents, doxycycline and absolute alcohol. The animals were sacrificed 8 weeks later, and were examined for patency of the vas and inflammatory response. Results revealed that vasopuncture did not produce obstruction. Vasography with water-soluble contrast media does entail a low risk of inflammation in the rat, but produces no obstruction. Intra-vas injection of doxycycline, injected by some for treatment of chronic seminal vesiculitis and perineal pain, is not deleterious in the rat model.     

Acute effect of vasectomy on the function of the rat epididymal epithelium and vas deferens

Persistent infertility after apparently successful vasectomy reversal is common. One possible etiology is epididymal epithelial dysfunction resulting in improper sperm maturation after vasectomy reversal. The epididymal epithelium secretes a number of proteins that are thought to be required for the maturation of sperm. Ligation of the vas deferens during vasectomy may affect the synthesis of some of these proteins. In the present study, the function of the epididymal epithelium was assessed at early times after vasectomy (1, 4, and 7 days) by measuring the level of mRNA of 4 secreted proteins: Crisp-1, clusterin, osteopontin, and transferrin. In addition, the site of synthesis of these proteins was determined by immunocytochemistry. The results demonstrated that the expression of Crisp-1 and clusterin, representative epididymal secretory proteins, was largely unaffected by vasectomy. However, osteopontin mRNA increased in the vas deferens in response to vasectomy. Immunocytochemical localization of osteopontin suggested that both infiltrating immune cells and deferential luminal epithelium were responsible for this up-regulation. Transferrin expression was viewed as a marker for immune cells at the site of injury. However, both the caput epididymis and deferential epithelia were found to express transferrin, in addition to immune cells. In conclusion, there appear to be only minor changes in expression of genes encoding epididymal secretory proteins acutely after vasectomy, but, not surprisingly, there was evidence of an inflammatory response after vasectomy.     

Obstruction of the vas deferens alters protein secretion by the rat caput epididymidal epithelium in vivo

Obstruction of epididymal lumen fluid flow alters the intraluminal environment and potentially changes epididymal epithelial cell function when those functions are dependent on intraluminal regulatory molecules. This investigation tested the hypothesis that obstruction of the rat vas deferens alters caput epididymidal protein synthesis and secretion In vivo. Adult male rats were subjected to vasal obstruction or sham operation. Fourteen days later, caput epididymides were subjected to in vivo microperfusion with medium containing a [35S]-amino acid mixture. At the end of a 3-hour perifusion, micropuncture was used to obtain caput lumen fluid (LF). Tubule extract (TE) was obtained as supernatant after homogenization and centrifugation of caput tubules. Tubule extract contained all [35S]-proteins synthesized within the 3-hour experiment, and LF contained the secreted [35S]-proteins. Radioactivity of trichloroacetic acid (TCA)-precipitable proteins in LF and TE was determined, and two-dimensional electrophoresis and autoradiography of each sample were carried out. The resultant autoradiograms were evaluated densitometrically. A protein synthesis index calculated from the TCA-precipitable radioactivity data demonstrated that a significant decline in overall protein synthesis was induced by vasal obstruction. Densitometry of autoradiograms demonstrated that the total number of radiolabeled proteins detected in both the LF and TE of obstructed animals was significantly smaller than the same number in control animals (P < 0.05). Autoradiography revealed seven major, consistently appearing gene products in LF, and these were subjected to amino acid sequence analysis. Cysteine-rich secretory protein (CRISP)-1 proteins were significantly reduced in the LF of obstructed animals, which implies that these proteins are dependent on luminal regulatory molecules for their normal production.     

Hormonal influence on the neurogenic response of the hamster vas deferens

The effect of castration on in vitro contractility of smooth muscle of the vas deferens and body of the bladder has been studied in the hamster. Castration produced supersensitivity to in vitro electrical stimulation and norepinephrine in the vas deferens, but had no effect on the body of the bladder. Castration also increased the maximum contractile response of the vas deferens to electrical stimulation, norepinephrine, ATP, acetylcholine and histamine. The changes in contractility of smooth muscle of the vas deferens developed slowly and may be explained by specific effects upon adrenergic and purinergic neurotransmission and/or non-specific effects upon smooth muscle cell membranes.     

Effects of variations in extracellular osmolality on spontaneous contractile activity and response to nerve stimulation in rat detrusor muscle in vitro

The effects of hyperosmolar (390, 590 mosm/kg) and hypoosmolar (260 mosm/kg) solutions on myogenic spontaneous contractile activity and response to nerve stimulation were studied on strips of rat detrusor muscle in vitro. In isotonic (290 mosm/kg) solution the mean spontaneous contractile activity was 2.1 +/- 0.6% and the amplitude of the largest spontaneous contractions was 9.8 +/- 3.0% of maximal response to nerve stimulation. In 390 mosm/kg the frequency of spontaneous contractions decreased, but due to a fourfold increase of contraction amplitude a threefold increase of mean contractile activity was recorded. In 260 mosm/kg a similar contraction pattern as in 290 mosm/kg was seen. The spontaneous contractions were resistant to tetrodotoxin (10(-5) g/ml) in all osmolalities. In 590 mosm/kg the spontaneous activity had ceased, and a continuous contracture (resistant to tetrodotoxin) was observed with an amplitude of 41 +/- 1% of the maximal response to nerve stimulation at 290 mosm/kg. Similar maximal responses to nerve stimulation were obtained in 260, 290, and 390 mosm/kg. The frequency-response relation in 390 mosm/kg had a leftward shift at low frequencies. In 590 mosm/kg no response to nerve stimulation or acetylcholine was noted, but the preparations contracted vigorously following depolarization with high-K+ solution.     

A model of an intraprostatic vas deferens in the rat

The study of the effect of hormones in seminal fluid upon prostate tissue is hampered by the lack of a suitable model. Such a model is described in this paper, and its possible usefulness is discussed. The vas deferens of the rat is moved from its normal position into a surgical incision into the ventral prostate. Squamous metaplasia of epithelium in prostatic acini at early stages is replaced by cuboidal epithelium. At later stages, normal-appearing glandular epithelium is seen as close as 50 micrometers to the vas deferens. The structure of the vas deferens is not affected.     

Effects of variations in extracellular pH on spontaneous contractile activity and response to nerve stimulation in smooth muscle from rat urinary bladder

The effects of variations in extracellular pH have been studied on rat detrusor muscle in vitro. At pH 7.4 a continuous low amplitude spontaneous contractile activity was found. At pH 6.75 the contractions became more regular with periods of relaxation between the contractions which had increased in amplitude. At pH 7.85 the reverse was found. The results are interpreted as a membrane effect of pH. No effect of pH on amplitudes of high-K(+)-induced contractures was found. Carbachol dose-response relations and maximal contraction amplitude to carbachol was similar at pH 7.4 and 6.75. A significant depression in response to nerve stimulation was, however, noted at pH 6.75. We suggest that, while the force output of the activated detrusor smooth muscle cell is unaffected by changes in extracellular pH, a prejunctional inhibition of nerve induced contraction might occur at low pH.     

Transcutaneous electrical nerve stimulation following appendicectomy: the placebo effect.

A controlled trial was undertaken to compare the efficacy of transcutaneous electrical nerve stimulation (TENS) with standard intramuscular opiate analgesia in the management of postoperative pain following appendicectomy. Consecutive patients undergoing emergency appendicectomy were randomised into control, sham TENS and active TENS groups. There was a significant decrease in pain severity and analgesic intake in both active and sham TENS groups when compared with the control group (P less than 0.01). No difference was demonstrated in pain severity between active and sham TENS groups but the active TENS group required slightly less analgesia. These results suggest that the major benefit of TENS in the postappendicectomy patient is due to its 'placebo effect' and its use in this situation cannot be recommended.     

迷走神经兴奋对内毒素血症大鼠肠道炎症反应的影响

目的:探讨电刺激迷走神经对内毒素血症大鼠肠道炎症反应的影响。方法:雄性 Wistar 大鼠随机分为4组。实验组大鼠分离并切断双侧迷走神经,静注脂多糖(LPS)后持续刺激左侧迷走神经20min,间隔10min 后重复刺激20min,共刺激3次,对照组无电刺激。分别于静注 LPS 后1h、1.5h 和2h 处死动物,测定肠组织 TNF-α、髓过氧化物酶(MPO)含量,并观察病理形态学改变。结果:迷走神经刺激组肠组织 TNF-α、MPO 含量显著低于 LPS 组和迷走神经切断复合 LPS 组(P<0.05),组织炎性损害明显减轻。结论:迷走神经兴奋能显著减轻内毒素血症大鼠肠道局部炎症反应,其机制可能与对抗致炎因子有关。     

The effect of stimulus frequency on the analgesic response to percutaneous electrical nerve stimulation in patients with chronic low back pain

Low back pain (LBP) is one of the most common medical problems in our society. Increasingly, patients are turning to nonpharmacologic analgesic therapies such as percutaneous electrical nerve stimulation (PENS). We designed this sham-controlled study to compare the effect of three different frequencies of electrical stimulation on the analgesic response to PENS therapy. Sixty-eight consenting patients with LBP secondary to degenerative lumbar disc disease were treated with PENS therapy at 4 Hz, alternating 15 Hz and 30 Hz (15/30 Hz), and 100 Hz, as well as sham-PENS (0 Hz), according to a randomized, cross-over study design. Each treatment was administered for a period of 30 min three times per week for 2 wk. The pre- and posttreatment assessments included the health status survey short form and visual analog scales for pain, physical activity, and quality of sleep. After receiving all four treatments, patients completed a global assessment questionnaire. The sham-PENS treatments failed to produce changes in the degree of pain, physical activity, sleep quality, or daily intake of oral analgesic medications. In contrast, 4-Hz, 15/30-Hz, and 100-Hz stimulation all produced significant decreases in the severity of pain, increases in physical activity, improvements in the quality of sleep, and decreases in oral analgesic requirements (P < 0.01). Of the three frequencies, 15/30 Hz was the most effective in decreasing pain, increasing physical activity, and improving the quality of sleep (P < 0.05). In the global assessment, 40% of the patients reported that 15/30 Hz was the most desirable therapy, and it was also more effective in improving the patient's sense of well-being. We conclude that the frequency of electrical stimulation is an important determinant of the analgesic response to PENS therapy. Alternating stimulation at 15-Hz and 30-Hz frequencies was more effective than either 4 Hz or 100 Hz in improving outcome measures in patients with LBP. Implications: The frequency of electrical stimulation seems to be an important determinant of the analgesic efficacy of percutaneous electrical nerve stimulation. Mixed low- and high-frequency stimulation was more effective than either low or high frequencies alone in the treatment of patients with low back pain.     

The evaluation of sympathetic system-related contractile activity of the rat vas deferens after ligation and intra-abdominal placement of the testis.

OBJECTIVE: To evaluate the contractile response of the vas deferens in a model of stress, to determine any changes in sympathetic activity as a result of stress in the ipsilateral testis, which decreases blood flow to the contralateral testis. MATERIALS AND METHODS: The study comprised two groups of six rats each; group 1 underwent a sham operation, and in group 2 the right testis was placed into the abdominal cavity and the vas deferens ligated. After 30 days, the vasa deferentia were resected bilaterally and their isometric contractions recorded. Electrical-field stimulation (EFS) was applied through a pair of platinum electrodes and concentration-response curves constructed for noradrenaline at 37 degrees C and to a solution containing 80 mmol/L K+. RESULTS: The vasa deferentia in both groups showed similar contractile responses to EFS, which were frequency-dependent and maximal at 80 Hz. Noradrenaline-induced contractile activity was lower in amplitude in the vasa deferentia of group 2 than in the contralateral and ipsilateral vasa deferentia of group 1, which were not significantly different from each other. All groups responded similarly to high K+. CONCLUSION: Intra-abdominal placement of the testes with vas deferens ligation decreased the contractile response to noradrenaline in the ipsilateral vas deferens without altering the contractile response to EFS and high K+. This difference could be caused by a reduction in the number of postjunctional alpha-adrenergic receptors or decreased receptor sensitivity. Both possibilities suggest that the vas deferens may initiate sympathetic activity, which may be responsible for contralateral testicular deterioration.     

Long-term use of sertraline leads to alterations in contractility of rat isolated vas deferens

Previous experiments with rat isolated vas deferens have shown that sertraline pretreatment inhibits contractile responses to noradrenaline, KCl, serotonin and electrical field stimulation. In the present study, the aim was to investigate the effects of long-term use of sertraline on contractile responses of rat isolated vas deferens. Fifteen Sprague-Dawley rats were given long-term (21 days) sertraline treatment, while another 15 were used as control. Both vas deferens were excised. Epididymal and prostatic segments of each underwent electrical field and chemical stimulation (noradrenaline, serotonin, acetylcholine, adenosine-triphosphate). Epididymal and prostatic segments had different contraction characteristics. Long-term sertraline treatment inhibited contractile responses of vas deferens segments to electrical field stimulation. The responses to noradrenaline were amplified with a left shift on both segments. Responses to serotonin had only a left shift on epididymal segments, while no contractile responses were observed on prostatic segments of the groups. Long-term treatment with sertraline had peripheral effects on rat vas deferens contractility, and some of the effects may be through mechanisms other than the inhibition of serotonin re-uptake.