The transillumination technique as a method for the assessment of spermatogenesis using medicinal plants: the effect of extracts of black maca (Lepidium meyenii) and camu camu (Myrciaria dubia) on stages of the spermatogenic cycle in male rats

Abstract

Transillumination technique for assessment of stages of spermatogenic cycle is a useful tool for toxicological studies. This study was designed to determine the effect of two medicinal plants on spermatogenesis in male rats using the transillumination technique. For this, the effect of the combination of a fruit with highest content of ascorbic acid (Myrciaria dubia, camu camu) and extract of black maca (Lepidium meyenii) on seminiferous tubule stages scored by transillumination on intact tubules in adult male rats was assessed. Animals were treated during seven days with vehicle, black maca, camu camu or a mixture of black maca?+?camu camu and assessed for daily sperm production (DSP), stages of spermatogenic cycle as well as antioxidant activity and levels of flavonoids and polyphenols. Black maca increased stages of spermiation (VII–VIII) and mitosis of germ cells (IX–XI), whereas camu camu increased stages of mitosis (IX–XI) and meiosis (XII). Mixture of maca?+?camu camu increased stages of spermiation, mitosis and meiosis. All treatments increased DSP (p?<?0.05) and epididymal sperm count (p?<?0.05). Total polyphenols, flavonoids levels and antioxidant activity were higher in camu camu (p?<?0.001) than in black maca. In conclusion, M. dubia (camu camu) has potential effects improving spermatogenesis and co-administered with maca increase stages of mitosis, meiosis and spermiation of the spermatogenic cycle as assessed by the transillumination technique. This technique is becoming increasingly a useful tool for assessment spermatogenesis.     

Effect of gamma irradiation on phenol content,antioxidant activity and biological activity of black maca and red maca extracts (Lepidium meyenii walp)

This study was performed to determine the effects of gamma irradiation on UV spectrum on maca, total content of polyphenols, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activities and in vivo biological activities of red and black maca extracts (Lepidium meyenii).

Adult mice of the strain Swiss aged 3 months and weighing 30–35?g in average were used to determine biological activities. Daily sperm production, effect on testosterone-induced prostate hyperplasia and forced swimming test were used to determine the effect of irradiation on biological activities of maca extracts.

Irradiation did not show differences in UV spectrum but improves the amount of total polyphenols in red maca as well as in black maca extracts. In both cases, black maca extract has more content of polyphenols than red maca extract (p?<?0.01). Gamma irradiation significantly increased the antioxidant capacity (p?<?0.05).

No difference was observed in daily sperm production when irradiated and nonirradiated maca extract were administered to mice (p?>?0.05). Black maca extract but not red maca extract has more swimming endurance capacity in the forced swimming test. Irradiation of black maca extract increased the swimming time to exhaustion (p?<?0.05). This is not observed with red maca extract (p?>?0.05). Testosterone enanthate (TE) increased significantly the ventral prostate weight. Administration of red maca extract in animals treated with TE prevented the increase in prostate weight. Irradiation did not modify effect of red maca extract on prostate weight (p?>?0.05).

In conclusion, irradiation does not alter the biological activities of both black maca and red maca extracts. It prevents the presence of microorganisms in the extracts of black or red maca, but the biological activities were maintained.     

Effects of long‐term treatment with fluoxetine and venlafaxine on rat isolated vas deferens

1 Antidepressant therapy is considered as one of the factors leading to male infertility. 2 In this study, the effects of long‐term treatment with fluoxetine or venlafaxine were investigated on electrical field stimulation (EFS, 1–64 Hz), noradrenaline (10^?8 to 10^?4 m ), serotonin (10^?8 to 10^?4 m ), adenosine 5′‐triphosphate [ATP (10^?8 to 10^?4 m )] and 80 mm KCl‐induced contractile responses in the epididymal and prostatic portions of rat isolated vas deferens strips. 3 Serotonin‐induced contractile responses were significantly increased in the epididymal portion of the vas deferens obtained from the fluoxetine‐treatment group, whereas in the prostatic portion there was no change. However, venlafaxine treatment had no effect on serotonin responses in the either portion of the vas deferens. Both fluoxetine and venlafaxine treatment significantly inhibited ATP‐evoked contractions of the prostatic and epididymal portions of the rat vas deferens, but had no effect on EFS, noradrenaline‐ and KCl‐evoked contractions of the vas deferentia in both portions. 4 In conclusion, these results suggest that chronic treatment with fluoxetine and venlafaxine affects vas deferens motility. Purinoceptors may, at least in part, responsible for the impaired motility in chronic treatment of venlafaxine and fluoxetine.     

Dose-response effect of black maca (Lepidium meyenii) in mice with memory impairment induced by ethanol

Previous studies have shown that black variety of maca has beneficial effects on learning and memory in experimental animal models. The present study aimed to determine whether the hydroalcoholic extract of black maca (BM) showed a dose-response effect in mice treated with ethanol 20% (EtOH) as a model of memory impairment. Mice were divided in the following groups: control, EtOH, ascorbic acid (AA) and 0.125, 0.25, 0.50 and 1.00?g/kg of BM plus EtOH. All treatments were orally administered for 28 days. Open field test was performed to determine locomotor activity and water Morris maze was done to determine spatial memory. Also, total polyphenol content in the hydroalcoholic extract of BM was determined (0.65?g pyrogallol/100?g). Mice treated with EtOH took more time to find the hidden platform than control during escape acquisition trials; meanwhile, AA and BM reversed the effect of EtOH. In addition, AA and BM ameliorated the deleterious effect of EtOH during the probe trial. Correlation analyses showed that the effect of BM a dose-dependent behavior. Finally, BM improved experimental memory impairment induced by ethanol in a dose-response manner due, in part, to its content of polyphenolic compounds.     

Effects of macamides on endurance capacity and anti-fatigue property in prolonged swimming mice

Context: Lepidium meyenii Walp. (Brassicaceae), most commonly known as “maca”, has been used as a food or folk medicine to improve vitality in Peru. Previous research demonstrated that lipid-soluble extract from maca improved swimming endurance capacity. Macamides are considered the typical lipid-soluble markers for maca and proved to have several pharmacological properties, such as improving sexual performance and neuroprotective activies.

Objective: The present study investigates the effects of macamides on endurance capacity and anti-fatigue property in prolonged swimming mice.

Materials and methods: The Balb/c mice were divided into seven groups: a control group, low-dose groups of N-benzyllinoleamide, N-benzyloleamide, and N-benzylpalmitamide, high-dose groups of these macamides. The macamides groups received the commercial products (12 and 40?mg/kg, ig), while the control group received vehicle for 21 d. On the 14th day, the mice were given the weight-loaded swimming test. On the 21st day, the mice were sacrificed immediately after 90?min swimming, and some biochemical parameters were measured.

Results and discussion: Compared with the control group, exhaustive swimming time was significantly prolonged in high-dose group of N-benzyloleamide (p?<?0.05); the levels of lactic acid (LD), blood ammonia (BA), and lactate dehydrogenase (LDH) were significantly decreased (p?<?0.05), whereas the levels of liver glycogen (LG) and non-esterified fatty acid (NEFA) were significantly increased (p?<?0.05) in high-dose group of N-benzyloleamide. The malondialdehyde (MDA) contents in the brain, muscle, and liver were significantly decreased (p?<?0.05), whereas superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) activities in the brain, muscle, and liver were significantly increased in high-dose group of N-benzyloleamide (p?<?0.05).

Conclusion: The results indicate that N-benzyloleamide has pharmaceutical property against exercise-induced fatigue, and this effect can be explained by the modulated energy metabolism and improved antioxidant status.     

1H NMR-based metabolic study reveals the improvements of bitter melon (Momordica charantia) on energy metabolism in diet-induced obese mouse

Context: Obesity can be ameliorated by some natural products such as polyphenol, flavones and saponin. As a typical medicinal plant, Momordica charantia L. (Cucurbitaceae) (bitter melon, BM) contains these natural chemicals and reduces diet-induced obesity in mice.

Objective: This study evaluates the metabolic effects of dietary BM supplement, investigates a global metabolic profile and determines associated perturbations in metabolic pathways.

Materials and methods: Male C57BL/6 mice were fed with low-fat diet (LFD), high-fat diet (HFD) and HFD supplemented with 5% BM based on 37.6?g/kg body weight in average for 12 weeks, respectively. Then energy metabolism was quantified using PhenoMaster/LabMaster. The spectroscopy of urine was acquired by nuclear magnetic resonance and latent biomarkers were identified. Pattern recognition analysis was used to discriminate associated metabolic profiles.

Results: Dietary BM supplement reduced body weight gain (?0.15-fold, p?<?0.01) and blood glucose levels (?0.19-fold, p?<?0.01) in HFD-fed mice. Meanwhile, the levels of energy metabolism were enhanced (0.08–0.11-fold, p?<?0.01). According to pattern recognition analysis, dietary BM supplement changed metabolic profiles in HFD-fed mice and the modified profiles were similar to those in LFD-fed mice. Finally, the mapping of metabolic pathways showed that dietary BM supplement primarily affected glucose metabolism-associated pathways.

Discussion and conclusion: The results indicated that BM improves weight loss in diet-induced obesity and elevate energy expenditure in HFD-fed mice. The pattern recognition with metabolic study may be used as a noninvasive detection method to assess the effects of dietary BM supplement on mouse energy metabolism.     

A comparison of histamine effects on the sympathetic neurotransmission of testicular capsule and rat vas deferens

Histamine is an important modulatory agent of the sympathetic neurotransmission, but its exact action on the testicular capsule or rat vas deferens is not fully understood. The present study sought to further investigate the functional effects of histamine on the neuronal and exogenous noradrenaline-induced contraction of the testicular capsule and rat vas deferens as well as to evaluate the contractile properties of this drug. The testicular capsule or vas deferens from Wistar rats, 3–4 months old, weighing 300–400 g, was isolated and mounted in organ baths for functional experiments. The results indicated that the neuronally evoked contraction of the testicular capsule was affected by histamine (10^?10 to 10^?8 M) with participation of inhibitory (H₃ receptors) and excitatory (H₁ receptors) receptors. Histamine (10^?7 to 10^?4 M) modulated the field-stimulated vas deferens by excitatory (H₂ receptors) and inhibitory (H₁ receptors) receptors. Histamine was able to decrease the tonic response for noradrenaline-induced contractions with participation of H₁ receptors (testicular capsule) and H₃ receptors (vas deferens) followed by nitric oxide generation. At high concentration, histamine exerts contractile effects in both tissues. In the testicular capsule, the histamine-induced contractions were related to H₁ receptor activation followed by release of prostaglandins. In contrast, the contractile effects of histamine in the vas deferens were related to H₂ receptor activation followed by release of catecholamines from sympathetic nerve endings. Therefore, our results indicate that histamine induced several effects on the sympathetic neurotransmission of rat testicular capsule and vas deferens. These effects are dependent on the concentration used and with participation of multiple histamine receptors.     

Localization of cyclooxygenase-2 in mice vas deferens and its effects on fertility upon suppression using nimesulide: a preferential cyclooxygenase-2 inhibitor

Accumulating evidence on constitutive expression of cyclooxygenase-2 (COX-2), one of the isoforms of enzyme cyclooxygenase (COX) the other isoform being cyclooxygenase-1 (COX-1), questions the safety profile of non-steroidal anti-inflammatory drugs (NSAIDs). This COX-2 isoform which is induced not only during inflammation but also by factors such as cytokines, steroid hormones and mitogenic stimuli is constitutively expressed in brain, kidney and reproductive organs. Present NSAIDs, particularly COX-2 inhibitors is no longer considered safe since suppression of COX-2 in tissues which it is constitutively expressed may lead to adverse effects. Though intense expression of COX-2 in vas deferens is proved, lack of information with respect to its function has attracted a wide scope for research as to whether COX-2 in vas deferens contributes to male fertility. In the present study, the authors investigated the localization of COX-2 as well as COX-1 in mice vas deferens and also assessed the activity of COX-2 and total prostaglandin (PG) levels in vas deferens. Further they suppressed the expression of COX-2 using a preferential COX-2 inhibitor nimesulide and analyzed the sperm from vas deferens for any defects. COX-2 was intensely expressed in the epithelial cells of mice vas deferens and nimesulide was able to effectively suppress most of COX-2 expression. A decrease in PG levels was observed initially but interestingly, the levels tend to rise on sustained suppression of COX-2. The motility of sperm was affected severely after 6h of nimesulide administration that suggested a crucial role of COX-2 towards fertility of mice sperm.     

Yacon roots (Smallanthus sonchifolius) improve oxidative stress in diabetic rats

Abstract

Context: Smallanthus sonchifolius (Poepp. and Endl.) H. Robinson, Asteraceae (yacon) roots are a natural product recognized by the traditional medicine to treat diabetes-related problems. There are no reports concerning the potential of yacon roots to reduce oxidative stress and ameliorate diabetes complications in diabetic animals.

Objective: This work analyzes the in vivo antioxidant activity and beneficial effects of yacon roots, using a model of streptozotocin-induced diabetes in rats.

Materials and methods: Lipid peroxidation and other indicators of oxidative stress were determined in liver and kidney homogenates from non-diabetic rats, untreated diabetic rats, and diabetic rats treated orally with yacon flour (340?mg fructooligosaccharide/kg/d) as a diet supplement for 90?d. Biochemical parameters were determined in liver, kidney, and blood at the end of the experimental period.

Results: Yacon supplementation to diabetic rats produced a significant decrease in malondialdehyde levels in both liver (?30.97%) and kidney (?19.15%). Hepatic superoxide dismutase and catalase activities were significantly lower in diabetic-treated rats (?13.46 and ?64.33%, respectively) compared with diabetic controls. Similar results were observed in kidney. The treatment of diabetic rats produced an increase of glutathione peroxidase and glutathione levels in liver (172.50 and 35.91%, respectively) and kidney (177.78 and 57.76%, respectively). Plasma cholesterol and triacylglycerol levels and liver fatty acid composition, which were altered in diabetic rats, reverted back to nearly normal with yacon treatment.

Conclusions: These results indicate that yacon root flour is a potential diet supplement with high in vivo antioxidant activity.     

Dose–response effect of black maca (Lepidium meyenii) in mice with memory impairment induced by ethanol

Previous studies have shown that black variety of maca has beneficial effects on learning and memory in experimental animal models. The present study aimed to determine whether the hydroalcoholic extract of black maca (BM) showed a dose–response effect in mice treated with ethanol 20% (EtOH) as a model of memory impairment. Mice were divided in the following groups: control, EtOH, ascorbic acid (AA) and 0.125, 0.25, 0.50 and 1.00?g/kg of BM plus EtOH. All treatments were orally administered for 28 days. Open field test was performed to determine locomotor activity and water Morris maze was done to determine spatial memory. Also, total polyphenol content in the hydroalcoholic extract of BM was determined (0.65?g pyrogallol/100?g). Mice treated with EtOH took more time to find the hidden platform than control during escape acquisition trials; meanwhile, AA and BM reversed the effect of EtOH. In addition, AA and BM ameliorated the deleterious effect of EtOH during the probe trial. Correlation analyses showed that the effect of BM a dose-dependent behavior. Finally, BM improved experimental memory impairment induced by ethanol in a dose–response manner due, in part, to its content of polyphenolic compounds.     

Effects of denervation on the sensitizing effect to noradrenaline induced by morphine in the vas deferens of mice treated chronically with morphine

The acute administration of morphine to the isolated vas deferens from mice chronically exposed to this analgesic, induced a facilitatory effect on the responses of the muscle to exogenous noradrenaline. It has been suggested that this sensitizing property of morphine might reflect a dependence-like state of the vas deferens. In the present paper, the capability of met- and leu-enkephalin to substitute for morphine was studied, as well as the influence of innervation on the apparent dependence state. The contractile responses to noradrenaline and to acetylcholine were increased after the administration of morphine to the bath containing a denervated vas deferences, prepared from chronically morphinized mice. Morphine administration facilitated noradrenaline- but not acetylcholine-induced contractile effects in vas deferens isolated from mice which had been chronically treated with either morphine or morphine plus guanethidine. The presence of met- or leu-enkephalin in the isolated vas deferens from chronically morphinized mice (either intact, denervated or treated with guanethidine) failed to sensitize contractile responses to noradrenaline or acetylcholine. It is concluded that (a) the sensitizing effect induced by morphine in the vas deferens from mice chronically treated with morphine is specific for the adrenergic neurotransmitter; (b) the effect of morphine is not mimicked by opiate peptides; and (c) denervation of the vas deferens of mice treated chronically with morphine does not suppress the noradrenaline-sensitizing property of morphine.     

Alpha(1D)-adrenoceptors mediate nerve and agonist-evoked contractions in mouse vas deferens: evidence obtained from knockout technology

1 It has been demonstrated that nerve-evoked contractions of the rat vas deferens involve alpha(1D)-adrenoceptors. Definitive evidence for a similar alpha(1D)-adrenoceptor-mediated response in mouse vas deferens has been more difficult to obtain. In this study, we have used alpha(1D)-adrenoceptor knockout (alpha(1D)-KO) mice to aid in the pharmacological characterization. 2 Mouse whole vas deferens was stimulated with a single pulse every 5 min. Once a stable response had been obtained, vehicle or antagonist was administered cumulatively at 5-min intervals and a response to stimulation obtained 5 min later. Cumulative concentration-response curves were also obtained for noradrenaline. 3 In vas deferens from alpha(1D)-KO mice, the contractile response to low concentrations of noradrenaline and the contractile response to a single stimulus were significantly reduced as compared to wild type (WT). 4 The alpha(1D)-adrenoceptor selective antagonist, BMY 7378, produced a concentration-dependent inhibition of single pulse-evoked contractions of vas deferens from WT and alpha(1D)-KO mice. BMY 7378 was significantly less potent in inhibiting stimulation-evoked contractions in vas deferens from alpha(1D)-KO mice. 5 It is concluded that alpha(1D)-adrenoceptors mediate a component of nerve- and agonist-evoked contractions of the vas deferens of WT mice.     

Protective effect of vitamin E against mercuric chloride reproductive toxicity in male mice

Mercury intoxication has been associated with male reproductive toxicity in experimental animals and mercury may have the potential to produce adverse effects on fertility in men. Vitamin E may protect against toxic effects of mercury in the liver and other tissues. To investigate the protective role of vitamin E against mercuric chloride toxicity for the testis, epididymis, and vas deferens of adult male mice, animals were treated with either mercuric chloride 1.25 mg/kg/day, vitamin E 2 mg/kg/kg, or a combination of the two treatments. Control animals were treated with water. Treatments were administered by daily gavage for 45 days. An additional group of animals treated with mercuric chloride were permitted to recover for 45 days after mercuric chloride treatments. Parameters studied included serum testosterone, epididymal sperm count, motility, and morphology, epididymal and vas deferens adenosine triphosphatase (ATPase), phosphorylase, sialic acid, glycogen and protein, testicular succinate dehydrogenase (SDH), phosphatases, cholesterol, ascorbic acid, and glutathione. Fertility was evaluated by sperm positive vaginal smears after overnight cohabitation with a female. Mercuric chloride produced a reduction in epididymal sperm count, sperm motility, and sperm viability, and there were no sperm-positive smears in this group. Biochemical tests from the male reproductive organs were also altered by mercuric chloride treatment. Coadministration of vitamin E with mercuric chloride prevented the changes in sperm and biochemical parameters and was associated with control rates of sperm positive smears after cohabitation. Animals given vitamin E with mercuric chloride also had lower concentrations of mercury in the testis, epididimyis, and vas deferens. Permitting animals to recover for 45 days after mercuric chloride treatment resulted in partial recovery of sperm and biochemical parameters. Vitamin E cotreatment has a protective role against mercury-induced male reproductive toxicity.     

Safety assessment of Hibiscus sabdariffa after maternal exposure on male reproductive parameters in rats

Context: Hibiscus sabdariffa L. (Malvaceae) is a species widely used in folk medicine for the treatment of some disorders. Objective: This study evaluated the effects of H. sabdariffa (HS) on the development of the male reproductive tract in rats following in utero exposure. Materials and methods: Pregnant rats received 250 or 500?mg/kg of HS extract or vehicle from gestational day 12 until day 21 of lactation. Results and discussion: Both doses of HS increased the body weight of male offspring at weaning, without compromising the puberty onset parameters. At puberty, there was a significant increase in the vas deferens absolute weight and a significant reduction in the relative weight of kidney at higher dose. These animals also presented a significant reduction in the sperm number in the caput/corpus of epididymis after exposure to both doses and a reduction in the sperm number in the cauda epididymis for the lower dose. At adulthood, the highest dose significantly reduced the sperm production in relation to controls and both doses provoked a reduction in the relative sperm number in the epididymis without affecting the sperm morphology. Conclusion: These findings demonstrated that maternal exposure to H. sabdariffa can adversely influence the male reproductive system in rats.     

The effect of number of stimuli and rate of stimulation on the inhibition by PGE1 of adrenergic transmission

An inverse correlation was found between the number of pulses and sympathetic blockade by PGE₁ (10^?8g/ml) in guinea-pig isolated field stimulated atria and vas deferens. The higher the number of pulses applied at a given frequency the smaller was the inhibition by PGE₁ of neuroeffector transmission. At 100 shocks using 10 Hz stimulation, PGE₁ no longer decreased the height of twitches of the guinea-pig vas deferens, however, the velocity of contractions was decreased. Sympathetic transmission in the rabbit jejunum was blocked by a somewhat higher dose of PGE₁ (3 × 10^?8g/ml). In this organ an increase in pulse number produced no detectable change in PGE₁-induced blockad. At a temperature of 37°C the vas deferens of the guinea-pig was highly sensitive to PGE₁, whereas that of the rat was virtually insensitive. On cooling the guinea-pig vas deferens to a temperature of 20°C the sensitivity to PGE₁ decreased and the shape of the shock number-effect curve became similar to that observed in that rat vas deferens. It is suggested, that the different shape of the curve may be caused by reduced release and/or effect of an inhibitory substance, probably prostaglandin. The biological responsesobtained with racemic PGE₁ were qualitatively identical with those elicited by natural PGE₁ the latter being about twice as potent.     

β-Endorphin. Biological activity of analogs containing dermorphin and dynorphin sequences: ileum and vas deferens assays

Biological activity of synthetic β-endorphin (β-EP) analogs containing dermorphin or dynorphin-A-(1 – 13) structure has been investigated using the guinea pig ileum and the vas deferens of the mouse, rat and rabbit. Replacement of NH₂-terminal 1–7 segment of camel β-EP [β_c-EP-(1–7)] with dermorphin caused a great increase in opiate potency of the analog. [Dermorphin (1–7)] -β_c-EP was 120 times more potent than β_c-EP in the guinea pig ileum assay, 49 times more potent in the mouse vas deferens assay; and only 4 times more potent in the rat vas deferens assay. Replacement of NH₂-terminal 1–13 segment of human β-EP [β_h-EP-(1–13)] with dynorphin-A-(1–13) caused an increase in opiate potency in both the guinea pig ileum and rabbit vas deferens assays, a complete loss of potency in the rat vas deferens assay, and no change in the mouse vas deferens assay. In comparison with dynorphin-A-(1–13), the hybrid peptide was less potent in the guinea pig ileum assay as well as in mouse and rabbit vas deferens assay. It is suggested that β_c-EP-(8–31) facilitates the dermorphin moiety to act on opiate μ and δ receptors but not on the ± receptor, while β_h-(14–31) reduces the action of dynorphin on μ, δ and k receptors.     

AN EXAMINATION OF AUTONOMIC NERVOUS FUNCTION IN GENETICALLY DIABETIC MICE

1 This study was designed to determine whether the autonomic innervation of the heart and vas deferens in genetically diabetic mice exhibited dysfunction similar to those seen in chemically diabetic animals and diabetic patients. 2 Diabetic mutant mice (outcrossed from the C57 BL/KS db/db strain) were compared with their non-diabetic litter-mates at age 20 to 22 weeks. Right and left atria and vasa deferentia were removed from freshly killed animals and subjected to nerve stimulation and treatment with noradrenaline (NA) or acetyl-choline (ACh) in organ baths. 3 Right atria from diabetic animals were less responsive to noradrenergic nerve stimulation than control preparations but there was no such difference between the noradrenergic responses of left atria from the two groups of mice. Both atria were hypersensitive to exogenous NA. 4 Atria from diabetic mice responded to cholinergic nerve stimulation and exogenous ACh in a fashion similar to those of non-diabetic mice. Likewise the responses of vasa deferentia to nerve stimulation were similar in the two groups. These findings are indicative of some autonomic nervous dysfunction characteristic, to an extent, of diabetes mellitus.     

Possible role of disturbed Na+ homeostasis in mouse vas deferens contractile hyperreactivity after imunological sensitization

In the present study we have investigated the involvement of sensitized mice immunoglobulins and some electrophysiological alterations that participate to the antigenic sensitization-induced hyperreactivity of isolated mouse vas deferens. Active sensitization was performed by subcutaneous injection of egg albumen. Contractile responses to noradrenaline were isometrically recorded in the isolated vas deferens. Low external Na⁺-induced contractions and rapid cooling contractures were evaluated. Resting membrane potential (Er) and intracellular Na activity were measured in control and actively sensitized vas deferens by using conventional KCl-filled and Na⁺-sensitive microelectrodes respectively. Active sensitization-induced hyperreactivity to noradrenaline was reproduced by in vitro passive sensitization of control vas deferens with sensitized mice immunoglobulins. The inhibition of the nitric oxide synthesis by N-nitro-L-arginine methyl ester (L-NAME) did not change control vas deferens reactivity in vitro to noradrenaline and acetylcholine. Rapid cooling contractures, performed after lowering external Na⁺ concentration, were not altered by active sensitization. However, sensitization increased significantly the strength of the low external Na⁺-induced contractions. In control vas deferens Er was a mean of –49.2±0.3 mV (mean ±SEM). Sensitization resulted in reduction of Er by 14 mV. In sensitized preparations, relative insensitivity of Er to ouabain, external K⁺ removal and cooling were observed. The intracellular Na⁺ activity was increased by about 40% in sensitized vas deferens. It is concluded that sensitization-induced hyperreactivity is mediated by immunoglobulins and produced smooth muscle cells depolarisation. The low Er of sensitized muscle may be partly the result of an increase in membrane permeability to Na⁺ which could interfere with intracellular Ca²⁺ homeostasis. Received: 26 May 1998 / Accepted: 22 July 1998     

Release of endogenous ATP from the vasa deferentia of the rat and guinea-pig by the indirect sympathomimetic tyramine

1 Adenosine 5′triphosphate (ATP) as well as [³H]-noradrenaline ([³H]-NA) is released by perfusion of the vas deferens with the indirect sympathomimetic tyramine (100 μM); this result is consistent with the concept of sympathetic cotransmission. 2 While tyramine produced a strong contraction in the vas deferens of the rat, it had little mechanical action in the guinea-pig vas deferens. This appears to be largely because tyramine induces considerably lower levels of release of both ATP and NA from the guinea-pig vas deferens compared to that of the rat. Furthermore, NA released by tyramine appears to release ATP from a secondary pool in the rat vans deferens, but not that of the guinea-pig, since prazosin reduced the tryamine-induced release of ATP in the rat vas deferens. 3 α, β -Methylene ATP (α, β -meATP) increased both the spontaneous release of ATP and the tyramine-evoked efflux of ATP and [³H]-NA. The basal and tyramine-induced efflux of [³H]-NA was also enhanced by the α₁-adrenoceptor antagonist, prazosin, suggesting that prejunctional α₁-adrenoceptors may modulate neurotransmitter release.     

N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4) impairs neurotransmission in the vas deferens of the rat

• 1.1. The in vitro effects of N-(2-chloroethyl)-N-ethyl-bromobenzylamine (DSP4) were studied in the rat vas deferens.
• 2.2. DSP4 inhibited the biphasic motor response induced by field stimulation in a concentration-dependent manner. The concentration of DSP4 that elicited 50% of the maximal inhibition of the twitch response induced by 3 Hz was 10 μM.
• 3.3. DSP4 10 μM abolished the motor response induced by exogenously applied noradrenaline and 0.1 mM ATP. Phentolamine (an α-adrenoceptor blocker) prevented DSP4 inhibitory effect.
• 4.4. DSP4 inhibitory effect was no due to the activation of α₂-presynaptic adrenoceptor mechanisms.
• 5.5. DSP4 impairs neurotransmission in the rat vas deferens by a postsynaptic α₁-adrenoceptor blockade and by an inhibition of the purinergic response.