Catecholamine Stimulation of Androgen Production by Mouse Interstitial Cells in Primary Culture

Innervation and serotoninergic receptors of the testis interact with local action of interleukin-1beta on steroidogenesis

Testosterone secretion by Leydig cells is affected by interleukin-1beta (IL-1beta). The aim of the present study was to investigate whether partial denervation of the testis or local administration of a serotonin (5-HT) receptor antagonist could alter the changes in testicular steoidogenesis induced by IL-1beta. Intratesticular administration of IL-1beta was combined with vasectomy or local injection of ketanserin (5-HT type 2 receptor antagonist) in immature hemicastrated rats and the effect of the interventions on testicular steroidogenesis was studied. One day after treatment with local injection of IL-1beta induced a significant rise in testosterone secretion that could be prevented by vasectomy (that also means transection of the inferior spermatic nerve). In a model in which neither IL-1beta nor ketanserin interfered with steroidogenesis, administration of the receptor antagonist just prior to IL-1beta treatment significantly reduced testosterone secretion. Data indicate interaction between testicular nerves and IL-1beta action and interaction between testicular 5-HT2 receptors and local effect of IL-1beta on testosterone secretion.

Central nervous system structures labelled from the testis using the transsynaptic viral tracing technique

In the present study, the transneuronal transport of neurotrophic virus technique was used to identify cell groups of the spinal cord and the brain that are transsynaptically connected with the testis. Pseudorabies virus was injected into the testis and after survival times of 3-6 days, the spinal cord and brain were processed immunocytochemically using a polyclonal antibody against the virus. Virus-infected perikarya were detected in the preganglionic neurones of the spinal cord (T10-L1, L5-S1) and in certain cell groups and areas of the brain stem, the hypothalamus and the telencephalon. In the brain stem, the cell groups and areas in which labelled neurones were present included, among others, the nucleus of the solitary tract, the caudal raphe nuclei, the locus coeruleus and the periaqueductal grey of the mesencephalon. In the hypothalamus, virus infected perikarya were observed in the paraventricular nucleus and in certain other cell groups. Telencephalic structures containing labelled neurones included the preoptic area, the bed nucleus of the stria terminalis, the central amygdala and the insular cortex. These data identify a multisynaptic circuit of neurones in the spinal cord and in the brain which may be involved in the control of testicular functions.

Differential effects of superior and inferior spermatic nerves on testosterone secretion and spermatic blood flow in cats

It has been postulated that testosterone secretion is partially regulated by signals from the spermatic nerves. To further examine this hypothesis in vivo, the superior (SSN) or the inferior (ISN) spermatic nerves were stimulated electrically (varying intensity, 25 Hz, 0.2 msec, 10 min) in anesthetized cats, determining the testosterone concentration and the blood flow in the spermatic vein. In some additional experiments arterial blood was sampled, and norepinephrine (NE) output was calculated. Stimulation of the SSN (25-35 V) increased the testosterone concentration in spermatic vein blood (P < 0.01 compared with prestimulation levels). The response varied among animals, reaching a 50-100% increase in some animals, whereas in others it ranged from almost undetectable to more than 10 ng/100 g x min. Under the same experimental conditions, the NE output increased from 135.4 +/- 99 to 1614.2 +/- 347 pg/ml (P < 0.01), and spermatic blood flow decreased from 24.1 +/- 1.42 to 20.2 +/- 1.65 ml/min x 100 g (P < 0.05) during nerve stimulation. By contrast, stimulation of the ISN (25-35 V) modified neither the testosterone concentration, the NE output, nor the blood flow in the spermatic vein. High intensity stimulation (36-70 V) of each spermatic nerve evoked different vascular and hormonal effects. SSN activation induced a marked decrease in spermatic blood flow during stimulation and an increase in the testosterone response, whereas ISN activation resulted only in an enhanced spermatic blood flow. Our results suggest that testosterone secretion, although mainly dependent on gonadotropin secretion, could be further regulated by neural inputs from the SSN acting directly or alternatively through changes in blood flow. It would appear that the SSN mainly supplies the vasoconstrictor fibers to the testis, whereas the ISN provides vasodilator fibers.

Ventral prostate structure and serum testosterone levels after chronic treatment with isoproterenol in adult rats with different androgen status

The effects of chronic administration of the beta-adrenergic agonist isoproterenol (ISO) (120 microg/kg per day; subcutaneously) on the ventral prostate structure and serum testosterone concentrations were examined in adult rats with different androgen status: intact, intact testosterone-injected (1 mg/rat), surgically and chemically castrated rats. Chemical castration was evoked by an intraperitoneal injection of ethane dimethanesulfonate (EDS) (75 mg/kg). A ventral prostate response was only observed in intact and chemically castrated animals. Stereological analysis revealed atrophic changes in the glandular compartment of the prostate of ISO-treated intact rats, but they were probably the consequence of significantly decreased serum testosterone levels. In addition, in these animals alterations were found in the morphometrical parameters of the ventral prostate blood vessels, their relative and total volumes being increased. In chemically castrated rats, administration of ISO from the day of EDS application partially prevented the postcastrational regression of the ventral prostate without affecting blood testosterone level. However, it seems that the discharge of glandular secretion was attenuated at the same time. These results show that chronic treatment with ISO may have both stimulatory and inhibitory effects on the rat ventral prostate depending on the androgen status of the animals and, accordingly, on the site of ISO-action.

Propranolol treatment affects ventral prostate blood vessels and serum testosterone concentrations in adult rats

The influence of prolonged beta-adrenergic receptor blockade on stereologic parameters of the ventral prostate and serum testosterone concentrations was examined in adult rats injected with propranolol (0.1 or 0.4 mg kg-1/day) for 15 or 30 consecutive days. Both doses of propranolol reduced the relative and absolute volume of the ventral prostate blood vessels. This effect was prevented by simultaneous administration of urapidil, an alpha 1-adrenergic receptor antagonist, indicating that a compensatory vasoconstriction took place as a consequence of propranolol treatment. Serum testosterone concentration was significantly increased following the 30-day application of the lower dose of the drug. These results show that prolonged administration of propranolol, although not affecting the epithelial component of the gland, may indirectly influence prostatic function by reducing the blood flow to the gland.

The combined effect of alcohol and physical exercise on serum testosterone, luteinizing hormone, and cortisol in males

The combined effect of alcohol and physical exercise on the serum levels of testosterone, luteinizing hormone, and cortisol was studied in healthy male volunteers by performing an exhaustive ergometer exercise (1) followed by alcohol intoxication (induced by 1.5 g of alcohol/kg body weight), (2) during alcohol intoxication (induced by 0.8 g of alcohol/kg body weight), and (3) during hangover (13 hr after a dose of 1.5 g of alcohol/kg body weight). Physical stress immediately before alcohol administration prolonged the depressant effect of alcohol on testosterone secretion. This seemed to be mainly a consequence of direct inhibition at the testicular level, even though the role of luteinizing hormone as a contributory regulatory factor cannot be totally ruled out. Cortisol response to exercise was not modified by alcohol under any of the experimental conditions.

Effects of guanethidine-induced sympathectomy on the spermatogenic and steroidogenic testicular functions of prepubertal to mature rats

Selective chemical sympathectomy of the internal genital organs of prepubertal to mature male Wistar rats was performed by chronic treatment with low doses of guanethidine. Sympathetic denervation caused an increase in intratesticular progesterone levels in prepubertal and early pubertal rats in addition to a decrease in androstenedione and testosterone levels in prepubertal animals, thus indicating a decrease in the conversion of progesterone into androgen, probably by blocking the steroidogenic enzymatic pathway at the 17 alpha-hydroxylase/17, 20 desmolase level. A lower degree of testicular maturation, probably related to reduced androgen activity, was observed in prepubertal and early pubertal sympathectomized rats. Concentration of spermatozoa, on the other hand, was increased in the enlarged cauda epididymidis of late pubertal and mature denervated animals. This result is discussed in terms of the impairment of epididymal mechanisms of seminal emission, fluid resorption and spermatozoal disposal.

The hypophyseal-testicular axis and sex accessory glands following chemical sympathectomy with guanethidine of pre-pubertal to mature rats

Selective chemical sympathectomy of the internal sex organs of prepubertal to mature male Wistar rats was performed by chronic treatment with low doses of guanethidine. Plasma testosterone and luteinizing hormone and the intratesticular level of testosterone were determined. The weight and fructose content of seminal vesicle and ventral prostate were also investigated. The results showed that sympathetic innervation is related to the control of the hypophyseal-testicular axis as well as to the growth and potential secretory activity of the male sex accessory glands.

Effect of adrenergic receptor blockade on plasma testosterone response to exercise in conscious dogs

The aim of this study was 1) to establish the relationship between testosterone (T) levels and the intensity and duration of exercise in conscious dogs, and 2) to investigate the involvement of the sympathetic system in the response of plasma T to acute exercise. The experiments were performed on 14 male mongrel dogs (20-25 kg) trained to run on a motor driven treadmill. Testosterone (T), cortisol, epinephrine, norepinephrine, lactate and haematocrit were measured in arterial blood samples. A brief intensive exercise (leading to exhaustion within 5 or 20 min) induced a marked increase in plasma T, while during more prolonged (60 min) exercise plasma T showed an initial increase followed by a secondary decrease. Blockade of the beta adrenergic receptors with propranolol (Inderal 0.5 mg/kg i.v.) did not modify the changes of plasma T during exercise, but blockade of alpha adrenergic receptors with phentolamine (Regitine 0.5 mg/kg) lowered the exercise induced rise in plasma T.

Catecholamine distribution in adult rat testis

Catecholamine distribution in the adult rat testis was examined using a sensitive radioenzymatic method. Norepinephrine was present in the capsule and the interstitial fluid, in higher concentrations than dopamine, while in the interstitial cell preparations only norepinephrine was found. Epinephrine was undetectable in all testicular compartments investigated. No catecholamines were found in the seminiferous tubules. Testicular denervation caused a significant decrease in capsular catecholamines, confirming the neural origin of these amines.

Viability of meiotic prophase spermatocytes of rats is facilitated in primary culture of dispersed testicular cells on collagen gel by supplementing epinephrine or norepinephrine: evidence that meiotic prophase spermatocytes complete meiotic divisions in vitro

Dispersed testicular cells prepared from 14-d-old rats were cultured on type 1 collagen gels using a medium composed of a 1:1 mixture of Ham's F12 medium and Leibovitz's L15 medium (F12-L15 medium) containing 10% (vol/vol) fetal bovine serum. The viability of the spermatogenic cells was facilitated by supplementing a rat adrenal extract into the medium. The effective substance(s) (the survival factor) was purified from acid extracts of adrenals by molecular sieve high performance liquid chromatography and identified as epinephrine and norepinephrine. Both epinephrine and norepinephrine promoted the survival of the spermatogenic cells with a half saturating dose of 10 ng/ml. The spermatogenic cells, which could be cultured for 2 wk on a collagen gel by supplementing with the survival factor (epinephrine or norepinephrine), were subjected to Giemsa staining and to DNA flow cytometry. The following results were obtained: a) The spermatogenic cells from 14-d-old rats did not contain spermiogenic cells (1c-cells). b) During a culture period of 2 to 7 d the ratio of meiotic prophase spermatocytes (4c-cells) to premeiotic cells (2c-cells) increased. On Day 7, more than 90% of the surviving cells were meiotic prophase spermatocytes. c) On Day 10, spermatids (1c-cells) appeared for the first time. The time of the first appearance of spermatids in the culture was consistent with that in vivo. These results suggest that both epinephrine and norepinephrine facilitated the viability of meiotic prophase spermatocytes and that a part of the meiotic prophase spermatocytes completed the meiotic divisions in the testicular cell culture.

A transplantable rat Leydig cell tumor--5. Cellular localization of beta-adrenergic and prostaglandin receptors and their effects on testosterone production

The cellular localization of beta-adrenergic and prostaglandin (PG) receptors and their effects on adenylate cyclase activity (AC) and testosterone production in vitro were investigated in a transplantable rat Leydig cell tumor (H-540). Separation of the tumor cells in Percoll gradients revealed that the specific binding of [3H]PGE1 and [125I]Cyanopindolol was found in the same fraction as that of [125I]LH. This fraction--judged by light microscopy of smears--consisted of tumor Leydig cells. In addition, [125I]cyanopindolol was found specifically bound in the red blood cell fraction. In the Leydig tumor cells, approx 25% of the beta-adrenergic receptors was identified as beta 1-receptors, whereas approx 75% of the receptors were of the beta 2-subtype. The AC in Percoll purified Leydig tumor cells was stimulated by hCG (6-fold), PGE1 (2-fold), PGE2 (1.5-fold), PGI1 (2-fold) and isoproterenol (2-fold). The AC in the red blood cell fraction was stimulated by isoproterenol whereas the PGs and hCG had little or no effect. hCG, isoproterenol and PGE1 were able to stimulate testosterone production in vitro. At 44 h incubation, PGE1 was the most potent stimulator of testosterone production. In conclusion, tumor Leydig cells possess hCG, PGE1, PGI2 and beta-adrenergic receptors coupled to the AC. PGE1 and beta-adrenergic agonists stimulate testosterone production after prolonged incubation in vitro.

Beta-adrenergic receptors and stimulatory effects of (-) isoproterenol on testosterone production in fetal mouse Leydig cells

Beta-adrenergic receptors were characterized in freshly excised fetal mouse testis using the radioiodinated antagonist iodocyanopindolol (ICYP). [125I]-CYP bound to a single class of high affinity sites with a KD value of 42.2 +/- 7.0 pM. Adrenergic agonists competed for ICYP binding sites with the following order of potency: (-)isoproterenol greater than (-)epinephrine much greater than (-)norepinephrine which is typical for a beta 2-adrenergic receptor. A selective beta 2-receptor antagonist ICI 118-551 showed an approximately 200 fold higher affinity than the beta 1-selective compound, betaxolol. The beta-adrenergic agonist (-)isoproterenol did not or slightly affect testosterone production by freshly isolated fetal Leydig cells. The ability of fetal Leydig cells to respond to (-)isoproterenol increased during culture. This change in responsiveness was not accompanied either by modification of the number of binding sites or by change in the binding affinity. Taken together these data suggest that i) the stimulatory effect of (-)isoproterenol on testosterone production by cultured fetal Leydig cells is mediated through beta 2-adrenergic receptors ii), the inability of freshly Leydig cells to respond to catecholamines is probably due to post receptor events.

The effect of long-term variation in sympathetic activity on testicular morphology in immature rats

In order to investigate the effect of increased and decreased sympathetic activity on testicular development, immature male rats were injected with isoproterenol or 6-hydroxydopamine from birth up to 49 days of age. Isoproterenol treatment resulted in a marked Leydig cell hypertrophy but the development of the spermatogenic epithelium was unaffected compared to that in saline treated controls. 6-hydroxydopamine treatment in a dose inhibiting the development of the parotid gland did not influence testicular development.

Characterization of beta-adrenergic receptors in dispersed rat testicular interstitial cells

Recent studies have shown that beta-adrenergic agents stimulate steroidogenesis and cyclic AMP formation in mouse Leydig cells in culture. To obtain information about the possible presence and the characteristics of a beta-adrenergic receptor in rat testicular interstitial cells, the potent beta-adrenergic antagonist [125I]cyanopindolol (CYP) was used as ligand. Interstitial cells prepared by collagenase dispersion from rat testis were incubated with the ligand for 2 h at room temperature. [125I]cyanopindolol binds to a single class of high affinity sites at an apparent KD value of 15 pM. A number of sites of 6,600 sites/cell is measured when 0.1 microM (-) propranolol is used to determine non-specific binding. The order of potency of a series of agonists competing for [125I]cyanopindolol binding is consistent with the interaction of a beta 2-subtype receptor: zinterol greater than (-) isoproterenol greater than (-) epinephrine = salbutamol much greater than (-) norepinephrine. In addition, it was observed that the potency of a large series of specific beta 1 and beta 2 synthetic compounds for displacing [125I]cyanopindolol in rat interstitial cells is similar to the potency observed for these compounds in a typical beta 2-adrenergic tissue, the rat lung. For example, the potency of zinterol, a specific beta 2-adrenergic agonist, is 10 times higher in interstitial cells and lung than in rat heart, a typical beta 1-adrenergic tissue. Inversely, practolol, a typical beta 1-antagonist, is about 50 times more potent in rat heart than in interstitial cells and lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Vasoactive intestinal peptide stimulates androgen biosynthesis by cultured neonatal testicular cells

Vasoactive intestinal peptide (VIP) was originally isolated from porcine duodenum and considered to be a gut hormone. Recent evidence indicates that it may also be involved in reproductive functions. In this study, a possible action of VIP on steroidogenesis by cultured testicular cells was investigated. Neonatal testicular cells were treated in vitro with hormones for 3 days and medium steroid or cAMP content was measured by radioimmunoassay. Treatment of cultured cells with VIP (10(-9) to 10(-6) M) increased the production of testosterone, progesterone, and pregnenolone in a dose-dependent fashion. Testosterone production in response to 10(-6) M VIP was about 5-10% of that maximally induced by LH. Addition of methyl-isobutyl-xanthine, a phosphodiesterase inhibitor, to the VIP-containing cultures significantly enhanced production of testosterone by 13-fold, of progesterone by 9-fold, and of pregnenolone by 2.5-fold as compared to treatment with VIP alone. Additional experiments also showed a dose-dependent stimulation of cAMP production by VIP. The VIP-related hormones PHM-27, secretin, and glucagon also stimulated progesterone and testosterone production with a potency order (PHM-27 greater than secretin greater than glucagon) consistent with that observed for other VIP receptor-mediated actions. A direct stimulatory effect of VIP on Leydig cells was indicated in studies on steroidogenesis by testicular cells separated on a metrizamide density gradient. In these studies, VIP stimulated androgen production in an LH-responsive subpopulation of testis cells but failed to affect steroid production in non-LH-responsive cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Beta-adrenergic stimulation of androgen production by fetal mouse Leydig cells in primary culture

The responsiveness of fetal mouse Leydig cells to catecholamines (epinephrine, norepinephrine), a beta-agonist agent (L-isoproterenol) and hCG was investigated in vitro. Fetal Leydig cells when freshly isolated were unable to respond to L-isoproterenol (10(-5) M). However, L-isoproterenol, epinephrine and norepinephrine significantly stimulated androgen production by fetal Leydig cells after 24 h of primary culture. Androgen production was increased in both conditions and to a greater extent by hCG. Propranolol blocked the stimulatory effect of L-isoproterenol and epinephrine. It is concluded that catecholamines can regulate fetal testosterone biosynthesis.

Beta 2-adrenergic stimulation of androgen production by cultured mouse testicular interstitial cells

The present studies characterized the beta-receptor subtype involved in androgen production by cultured mouse testicular interstitial cells and explored the possible stimulation of androgen release by alpha-adrenergic agonists. During a 3-hour incubation period, LH and a non-specific beta-adrenergic agonist, L-isoproterenol steadily increased androgen production with a similar time-course. Isoproterenol, epinephrine, norepinephrine and a specific beta 2-receptor agonist, salbutamol stimulated androgen release in a concentration-dependent manner. The concentrations of the agonists required for half-maximum stimulation (EC50) were approximately 1 nM (isoproterenol), 8 nM (epinephrine), 9 nM (salbutamol) and 2 microM (norepinephrine) giving an order of potency of isoproterenol greater than epinephrine = salbutamol much greater than norepinephrine. L- but not the D-isomer of isoproterenol induced androgen production. A non-selective beta-receptor antagonist, propranolol, abolished androgen production induced by isoproterenol. A selective beta 2-receptor antagonist ICI 118,551 inhibited the isoproterenol effect in a concentration-dependent manner with half-maximum inhibition (IC50) at approximately 23 nM. The beta 1-receptor antagonists, metoprolol and atenolol had no effect on isoproterenol-induced androgen release. The stimulatory effect of norepinephrine (an alpha- and beta-agonist) was completely (100%) abolished by propranolol, unaffected by the alpha-antagonist phentolamine and only partially (35%) inhibited by phenoxybenzamine. Phenoxybenzamine and the alpha 2-agonist, clonidine reduced basal androgen production. These studies indicate that androgen production by primary cultures of mouse testicular interstitial cells occurs exclusively via the beta 2-receptor subtype and that alpha-receptor agonists do not stimulate androgen release by these cells.

The effects of adrenergic and cholinergic agents on progesterone production by human corpus luteum in vitro

We investigated the effects of adrenergic and cholinergic agents on human corpus luteum production of progesterone in vitro. Luteinizing hormone (LH) (50 ng/ml), dibutyryl cyclic adenosine monophosphate (Bu2cAMP) (10(-3)M), and prostaglandin E2 (PGE2) (1 microgram/ml) significantly stimulated the production of progesterone in short-term (4-hour) cell suspensions of five early and middle luteal phase corpora lutea. The adrenergic agents isoproterenol, norepinephrine, and epinephrine, and the cholinergic agents acetylcholine and carbachol at concentrations up to 10(-4)M did not alter basal or stimulated production of progesterone. Similarly, in long-term (10-day) monolayer cultures of cells from four corpora lutea, human chorionic gonadotropin (hCG) (50 ng/ml) and PGE2 stimulated, but none of the adrenergic or cholinergic agents altered, the production of progesterone significantly, except for an inhibitory effect of norepinephrine and carbachol in the presence of 17 beta-estradiol (10(-7)M) added to the culture medium. These results differ strikingly from the consistent stimulatory effect of beta-adrenergic agents on the luteal production of progesterone in several animal species.

beta-adrenergic agonist induced androgen production during primary culture of mouse Leydig cells

Mouse testicular interstitial cells and Leydig cells prepared by density-gradient centrifugation developed the ability to increase androgen production in response to isoproterenol between 24 and 48 hr of primary culture. Although exposure of the cultures to isoproterenol or cycloheximide inhibited the acquisition of responsiveness to beta-adrenergic stimulation, in vivo treatment with propranolol did not alter the time at which cultures became responsive to isoproterenol. It is concluded that the acquisition of beta-agonist responsiveness during culture is not a recovery from beta-adrenergic desensitization.