Evidence for a single opioid receptor type on the field stimulated rat vas deferens

A series of opioids have been used to study the heterogeneity of the opioid receptor system in rat vas deferentia. β-Endorphin, etorphune, etonitazine, D-Ala²-Nle⁵ (des-COOH) enkephalin and, sufentanil behave as full agonists in this tissue preparation. Ketobemidone, α(+)-N-allyl normetazocine, morphine and oxymorphone show little or no biological activity. In fact, the latter four drugs were able to inhibit the biological effects of β-endorphin, etorphine and sufentanil in a concentration dependent fashion. These data suggest that there is only one opioid receptor type in the rat vas deferens. These observations are discussed in terms of the binding modes for a series of drugs to an homogeneous receptor system.     

Effects of endothelins on nerve-mediated contractions of the mouse vas deferens

The effects of 3 endothelins (ETs) on sympathetic nerve-mediated responses were investigated in the mouse isolated vas deferens. ET-1, ET-2 and, to a lesser extent, ET-3 (0.3–30 nM) caused marked and sustained potentiation of responses to field stimulation at 0.1 Hz, but had little effects, if any, on baseline tension. Incubation with nicardipine (30 nM) strongly inhibited the development of twitch potentiation by the ETs. Twitches potentiated beforehand by ET-1 (10 nM) displayed marked resistance to inhibition by nicardipine, so that 10 μM of nicardipine only reversed part of the effect of ET-1. ET-1 also enhanced both components of the response to high frequency field stimulation (2 to 16 Hz) and contractions induced by submaximal concentrations of noradrenaline, ATP or KCl. All effects of ET-1 were mimicked by Bay K 8644, an activator of L-type Ca++ channels. It is concluded that ETs increase the efficacy of sympathetic neurotransmission in the mouse vas deferens by, at least in part, a postjunctional mechanism which involves activation of L-type Ca⁺⁺ channels.     

The effect of adenosine and beta-endorphin on the contractions of the vas deferens in rats with various durations of ethanol narcosis

Action of ethanol on animals with different predisposition to alcohol consumption depended on the level of ethanol metabolism or sensitivity of nervous system to alcohol. There was studied the ethanol effects on contraction of rat vas deferens. Such an approach enables to distinguish the metabolic effects from action on nervous system. It was shown, that dose of ethanol, which inhibits the contraction of rat vas deferens of by 50% is the same in both groups of rats, but the ED50 of adenosin and beta-endorphin were 1.7 and 4.7 times lower for vas deferens of predisposed rats. It's possible to suggest the differences between two groups of rats to be connected with the effects of ethanol on purinergic and endorphinergic system, but not with ethanol itself.     

Effects of veratrine and paeoniflorin on isolated mouse vas deferens

In this study, we attempted to identify the interactions and mechanisms between veratrine and paeoniflorin on isolated mouse vas deferens. Paeoniflorin had no effect on isolated mouse vas deferens. Veratrine (1 x 10(-5) approximately 1 x 10(-3) g/ml) could directly induce contraction of isolated rat and mouse vas deferens. The concentration induced by veratrine (1 x 10(-5) g/ml) was completely inhibited by Ca2+-free solution and verapamil (1 x 10(-5) M), in both the epididymal and the prostatic portions of isolated mouse vas deferens. Naloxone (1 x 10(-5) M) did not alter the contraction induced by veratrine (1 x 10(-5) g/ml) in either the epididymal or the prostatic portions of isolated mouse vas deferens. Paeoniflorin (4.8 x 10(-5) g/ml) inhibited the contraction induced by veratrine (1 x 10(-5) g/ml) in both the epididymal and the prostatic portions of isolated mouse vas deferens. Paeoniflorin (4.8 x 10(-5) g/ml) potentiated norepinephrine (1 x 10(-5) M)-induced phasic contraction in the epididymal portion, but decreased contractions in the prostatic portion. Paeoniflorin (4.8 x 10(-5) g/ml) increased KCI (56 mM)-induced phasic contraction in the epididymal portion, but decreased the tonic contraction in either the epididymal or the prostatic portion. Veratrine (1 x 10(-5) g/ml)-induced contractions could be decreased by pretreatment with ryanodine (1 x 10(-5) M) in both the epididymal and the prostatic portions. Pretreatment with the combination of paeoniflorin (4.8 x 10(-5) g/ml) and ryanodine (1 x 10(-5) M) did not potentiate the inhibition of paeoniflorin in the veratrine-induced contraction in both the epididymal and the prostatic portions of isolated mouse vas deferens.     

Influence of nonakhlazin on adrenergic neurotransmission in the vas deferens of rats]

The effect of a new antianginal drug--nonachlazine on the adrenergic neurotransmission in the isolated rat vas deferens was studied by examining the vas deferens contractions in response to the transmural electric stimulation of the postganglionic sympathetic nerves and addition of noradrenaline (NA) or BaCl2. After the nonachlazine treatment the NA content in the vas deferens was also studied by the spectrofluorometric method. Besides, the effect of the drug on the uptake of the exogenous NA was investigated. Nonachlazine was found to possess some sympatholytic and spasmolytic effect and could block the uptake of the exogenous NA greatly.     

Antifertility effect of sympathomimetic drugs on male rats when applied locally to the vas deferens.

Local application of collars containing 25% methoxamine, 50% or 75% tyramine or 50% norephedrine to both vasa deferentia of rats caused a reduction in fertility but not in their ability to mate. A gradual return to fertility was seen in those animals which received the lower dose of tyramine or norephedrine, while the other treatments caused a permanent reduction in fertility. The cause of sterility was production of azoospermic ejaculates resulting from either a block in sperm transport in the vas deferens or from a deficiency in the ejaculatory mechanism. Only methoxamine caused a mechanical obstruction of the vas deferens, but it is possible that the other drugs caused a sustained spasm. An emission defect could have been due to transmitter depletion, receptor-specific desensitization or presynaptic alpha-adrenoreceptor-mediated inhibition. Spermatozoa from the cauda epididymidis were immotile following the treatments.     

Selective receptors for beta-endorphin on the rat vas deferens.

The isolated rat vas deferens, being insensitive to morphine, contains selective binding sites for β-end-orphin. A half-maximal inhibition of twitch tension evoked by electrical stimulation is established with 100 nM β-endorphin, while fragments of β-endorphin, that is, methionine-enkephalin, α- and γ-endorphin, are almost ineffective. The opiate alkaloid etorphine, a powerful inhibitor of guinea-pig ileum and mouse vas deferens, is 100-fold less potent on the rat vas deferens. The unique β-endorphin activity suggests very specific binding sites for this peptide, which cannot be related to the μ- or δ-receptors so far described for opiods on isolated preparations.     

Difference of fertilizing capacity between testicular sperm and vas deferens sperm in Cynops pyrrhogaster

The fertilizing capacity was compared between testicular and vas deferens sperm in Cynops pyrrhogaster. The testicular sperm was not capable of fertilizing jelly eggs. In contrast, the vas deferens sperm was already capable of fertilizing the newt jelly eggs. There was no inhibitory factor for fertilizing jelly eggs in the testis. These results suggest that the testicular sperm is immature as to the fertilizing capacity. The testicular sperm gained the fertilizing capacity for the jelly eggs by treatment with Holtfreter's solution or 1/20 strength Holtfreter's solution. The treatment may promote the step of maturation to achieve the fertilizing capacity. The treated testicular sperm did not fertilize dejellied eggs, although vas deferens sperm fertilized dejellied eggs. Therefore, the maturation state of the treated testicular sperm is different from that of vas deferens sperm. Newt sperm may be matured within the vas deferens, as the newt does not have an organ like the mammalian epididymis.     

Foreign DNA introduced into the vas deferens is gained by mammalian spermatozoa

The uptake of exogenous DNA by mouse and rat spermatozoa was analyzed using in vitro and in vivo methods. Two DNA constructs were used, one containing the Growth hormone (GH) gene and the other the c-myc oncogene linked to the αA-crystallin promoter (CPV-1 plasmid). For the in vitro approach, washed epididymal spermatozoa were incubated for 2 hr in the presence of linearized DNA. For in vivo experiments, DNA was injected into the proximal region of the vas deferens, and spermatozoa were recovered 6 hr later. In situ hybridization employing fluorescent markers and electron microscopy were used to localize the exogenous genes in spermatozoa. The precise localization of the foreign DNA in spermatozoa was visualized by tridimensional reconstructions using a confocal laser microscopy. Uptake of exogenous DNA occurred in 60–70% of the spermatozoa after in vitro or in vivo treatments. A positive signal was detected in the sperm nucleus and was not affected by DNase treatments. Incorporation of exogenous DNA was also evaluated by slot blot and PCR techniques using the DNA isolated from the sperm nuclei and the corresponding labelled probes. Comparison of a nucleotide sequence between the DNA isolated from in vivo treated spermatozoa and CPV-1 plasmid showed a 98.6% identity. These results show the in vivo capacity of spermatozoa to incorporate exogenous DNA, the ability of this DNA to reach the nucleus, and also demonstrate that epididymal and vas deferens secretions do not block these capacities. Mol. Reprod. Dev. 51:42–52, 1998. © 1998 Wiley-Liss, Inc.     

Effects of chemical occlusion of vas deferens on the reproductive organs in gerbil Meriones hurrianae Jerdon.

Male gerbils were sterilized by giving a single injection of a sclerosing chemicial (5% KMnOH) directly into the vasa. After 3 weeks the gerbils were killed. Testes, accessory sex organs, and thyroid and adrenal glands were removed and weighed. Halves of testis and epididymides were fixed in Bouin's fluid fo r microscopic study. The remaining halves were frozen and total RNA, protein, sialic acid, seminal vasicular fructose, and testicular lipids were later determined. Cholesterol estimations were also made. 2 weeks following vas injections animals were tested by exposing them to cycling estrous females. 21 days later the females were examined for possible implantation sites. It was shown that the males had been sterile. Weights of testicles, accessory sex organs, thyroid and adrenal gland remained normal, except that there was a significant increase in the weight of the ventral prostate. No histological changes were found in the testes. Protein content of the testes, epididymides, and seminal vesicles did not change. A decrease in RNA was noted. Sialic acid levels did not alter. Cholesterol and total lipids were normal. Alkaline phosphatase activity in the testes and epididymides had not changed after 3 weeks. Vasicular fructose was normal. Complete occlusion of the vasa resulted. After 100 days there was no return to fertility. The results appear to be permanent.