Spermatogonial stem cells (SSCs) are essential for spermatogenesis, and these adult tissue stem cells balance self-renewal and differentiation to meet the biological demand of the testis. The developmental dynamics of SSCs are controlled, in part, by factors in the stem cell niche, which is located on the basement membrane of seminiferous tubules situated among Sertoli cells. Sertoli cells produce glial cell line-derived neurotrophic factor (GDNF), and disruption of GDNF expression results in spermatogenic defects and infertility. The GDNF signals through a receptor complex that includes GDNF family receptor alpha1 (GFRA1), which is thought to be expressed by SSCs. However, expression of GFRA1 on SSCs has not been confirmed by in vivo functional assay, which is the only method that allows definitive identification of SSCs. Therefore, we fractionated mouse pup testis cells based on GFRA1 expression using magnetic activated cell sorting. The sorted and depleted fractions of GFRA1 were characterized for germ cell markers by immunocytochemistry and for stem cell activity by germ cell transplantation. The GFRA1-positive cell fraction coeluted with other markers of SSCs, including ITGA6 and CD9, and was significantly depleted of KIT-positive cells. The transplantation results confirmed that a subpopulation of SSCs expresses GFRA1, but also that the stem cell pool is heterogeneous with respect to the level of GFRA1 expression. Interestingly, POU5F1-positive cells were enriched nearly 15-fold in the GFRA1-selected fraction, possibly suggesting heterogeneity of developmental potential within the stem cell pool.

Krachaidum (KD, Kaempferia parviflora Wall. Ex. Baker), a native plant of Southeast Asia, is traditionally used to enhance male sexual function. However, only few scientific data in support of this anecdote have been reported. The present study investigated the effects offeeding three different extracts of KD (alcohol, hexane, and water extracts) for 3-5 weeks on the reproductive organs, the aphrodisiac activity, fertility, sperm motility, and blood flow to the testis of male rats. Sexual performances (mount latency, mount frequency, ejaculatory latency, postejaculatory latency) and sperm motility were assessed by a video camera and computer-assisted sperm analysis respectively, while blood flow to the testis was measured by a directional pulsed Doppler flowmeter. The results showed that all extracts of KD had virtually no effect on the reproductive organ weights even after 5 weeks. However, administration of the alcohol extract at a dose of 70 mg/kg body weight (BW)/day for 4 weeks significantly decreased mount and ejaculatory latencies when compared with the control. By contrast, hexane and water extracts had no influence on any sexual behavior parameters. All types of extracts of KD had no effect on fertility or sperm motility. On the other hand, alcohol extract produced a significant increase in blood flow to the testis without affecting the heart rate and mean arterial blood pressure. In a separate study, an acute effect of alcohol extract of KD on blood flow to the testis was investigated. Intravenous injection of KD at doses of 10, 20, and 40 mg/kg BW caused dose-dependent increases in blood flow to the testis. The results indicate that alcohol extract of KD had an aphrodisiac activity probably via a marked increase in blood flow to the testis.

Excess formation of nitric oxide and superoxide by-products (peroxynitrite, reactive oxygen, and reactive nitrogen species) attenuates cholinergic transmission potentially having a role in Alzheimer disease pathogenesis. In this study, we investigated mechanisms by which acute exposure to peroxynitrite impairs function of the sodium-dependent hemicholinium-3 (HC-3)-sensitive choline transporter (CHT) that provides substrate for acetylcholine synthesis. The peroxynitrite generator 3-morpholinosydnonimine (SIN-1) acutely inhibited choline uptake in cells stably expressing FLAG-tagged rat CHT in a dose-and timedependent manner, with an IC 50 ϭ 0.9 Ϯ 0.14 mM and t 1/2 ϭ 4 min. SIN-1 significantly reduced V max of choline uptake without altering the K m . This correlated with a SIN-1-induced decrease in cell surface CHT protein, observed as lowered levels of HC-3 binding and biotinylated CHT at the plasma membrane. It is noteworthy that short-term exposure of cells to SIN-1 accelerated the rate of internalization of CHT from the plasma membrane, but it did not alter return of CHT back to the cell surface. SIN-1 did not disrupt cell membrane integrity or cause cell death. Thus, the inhibitory effect of SIN-1 on choline uptake activity and HC-3 binding was related to enhanced internalization of CHT proteins from the plasma membrane to subcellular organelles.

Intravenous administration of methacholine (200 micrograms/kg) caused no changes in the seminiferous tubules of rats, but significantly increased intraluminal pressures and contractility of the caput, the corpus and the cauda epididymidis. The effect of methacholine was abolished by pretreatment with atropine (500 micrograms/kg), but not by phentolamine (400 micrograms/kg) or propranolol (400 micrograms/kg). Adrenaline (5-40 micrograms/kg), noradrenaline (5-40 micrograms/kg) and phenylephrine (100-400 micrograms/kg) had no effect on the seminiferous tubules, but dose-dependently elevated intraluminal pressures and enhanced the contractility of all regions of the epididymis. Isoproterenol (100-800 micrograms/kg) did not affect intraluminal pressures of the seminiferous tubules and the epididymal duct. The stimulatory effect of adrenergic agonists was specifically blocked by phentolamine, but not by propranolol or atropine. Cholinergic and adrenergic antagonists did not alter spontaneous contraction of the epididymis. The results suggest that the contractility of all segments of the rat epididymis, but not the seminiferous tubules, can be increased by autonomic drugs. The enhancing effect of adrenergic drugs is probably the result of activation through alpha-adrenergic receptors.

The major glycoprotein on the plasma membrane of testicular spermatozoa labelled with the galactose oxidase/NaB3H4 technique has mol.wt. 110 000. As spermatozoa pass through the epididymis, labelling of this glycoprotein disappears and is replaced by labelling of a 32 000-mol.wt. protein. The latter protein is a major component of epididymal secretions. The evidence suggests that it is inserted into or absorbed on to the plasma membrane, and since its appearance on spermatozoa correlates with the acquisition of fertilizing capacity it should serve as a good marker for assessing maturation in vitro.

This study was undertaken to determine if sympathetic nerve impulses modify lacrimal gland fluid (LGF) flow, which was continuously recorded from a cannula in the excretory duct of the lacrimal gland in rabbits anesthetized with pentobarbital sodium. The preganglionic trunk of the superior cervical ganglion was stimulated with electrical stimuli during pilocarpine-induced and reflexly induced secretion. Stimuli equal to or 6-8 times stronger than the intensity that produced maximal pupil dilation caused inhibition followed by poststimulus enhancement of LGF flow when the prestimulus LGF flow was greater than 3.0 mul/min. When the prestimulus LGF flow was less than 0.8 mul/min, the stronger stimulation enhanced LGF flow but the weaker stimulation produced inhibition followed by poststimulus enhancement of LGF flow. Although no measurements of lacrimal gland blood flow were made, the alterations in these responses, which occurred during alpha- and beta-adrenergic blockade, were consistent with the changes in sympathetically induced blood flow that occur during alpha- and beta-blockade in other organs.

Transport of spermatozoa through different regions of the epididymis has been followed by labelling testicular spermatozoa with [3H]thymidine in intact rats and in rats in which the efferent ducts were ligated or the testes were removed. In intact rats, the transit times of epididymal spermatozoa from the initial segment to the caput, from the caput to the corpus, and from the corpus to the cauda were 2, 4 and 2 days, respectively, giving a total transit time of 8 days. After bilateral castration, labelled spermatozoa were transferred from the initial segment into the proximal cauda by 2 days and appeared in the ductus deferens by 4 days. This effect was prevented by a daily subcutaneous injection of testosterone propionate (0.2 mg/kg). Bilateral efferent duct ligation had only a slight effect on the passage of epididymal spermatozoa. The results indicate that epididymal sperm transport is enhanced after androgen withdrawal.

Objective-To observe whether there are any injuries to muscle and deleterious eVects on the liver and kidneys during training and after competition in Thai boxers. Methods-Serum levels of intracellular enzymes and specific markers in the urine were measured during training and after fighting in Thai boxers. Results-During the training period, the activities of muscle enzymes were significantly increased whereas those of the liver enzymes and creatinine clearance were not changed. After a match, on the other hand, both liver and muscle enzyme activities were elevated but renal function was decreased. Conclusions-The training protocol for Thai boxers has virtually no deleterious eVect on liver and renal function, but damage to skeletal muscle cells may occur. However, competition may cause muscle injury without any obvious damage to the liver and kidneys. (Br J Sports Med 1998;32:304-308)