Multiple effects of sibutramine on ejaculation and on vas deferens and seminal vesicle contractility

Can exposure to lisdexamfetamine dimesylate from juvenile period to peripubertal compromise male reproductive parameters in adult rats?

Lisdexamfetamine (LDX) is a d-amphetamine prodrug used to treat attention deficit and hyperactivity disorder, a common neurodevelopmental disorder in children and adolescents. Due to its action mediated by elevated levels of catecholamines, mainly dopamine and noradrenaline, which influence hormonal regulation and directly affect the gonads, this drug may potentially disrupt reproductive performance. This study evaluated the effects of exposure to LDX from the juvenile to peripubertal period (critical stages of development) on systemic and reproductive toxicity parameters in male rats. Male Wistar rats (23 days old) were treated with 0; 5.2; 8.6 or 12.1 mg/kg/day of LDX from post-natal day (PND) 23 to 53, by gavage. LDX treatment led to reduced daily food and water consumption, as well as a decrease in social behaviors. The day of preputial separation remained unaltered, although the treated animals exhibited reduced weight. At PND 54, the treated animals presented signs of systemic toxicity, evidenced by a reduction in body weight gain, increase in the relative weight of the liver, spleen, and seminal gland, reduction in erythrocyte and leukocyte counts, reduced total protein levels, and disruptions in oxidative parameters. In adulthood, there was an increase in immobile sperm, reduced sperm count, morphometric changes in the testis, and altered oxidative parameters, without compromising male sexual behavior and fertility. These findings showed that LDX-treatment during the juvenile and peripubertal periods induced immediate systemic toxicity and adversely influenced reproductive function in adult life, indicating that caution is necessary when prescribing this drug during the peripubertal phase.

Impact of timing of the anorexigen sibutramine administration on reproductive end-points of male rats

Sibutramine is a non-selective serotonin-norepinephrine reuptake inhibitor orally administered for weight loss. In a previous study, we showed pharmacological mechanisms involved in the reduction of sperm quality and fertility of rats exposed for 30 days to this anorexigen in the light phase of the light-dark (l/d) cycle. It is already known that rodents are nightlife animals, with higher metabolic activity during the dark phase than in the light phase of the light-dark (l/d) cycle. Thus, the present study aimed to investigate whether the deleterious effects on reproductive parameters after sibutramine administration would be enhanced after a shorter period of exposure during the dark phase of the l/d cycle. For this, adult male Wistar rats were treated with sibutramine (10 mg/kg/d) or vehicle for 15 days during the dark phase of the l/d cycle. Sibutramine treatment decreased final body and reproductive organ weights, as well as serum testosterone levels. Sperm transit time through the epididymis was accelerated, and sperm concentration and motility were diminished in the sibutramine-exposed rats. The decrease in sperm concentration was also verified in the epididymal histological sections. In conclusion, the deleterious effects of sibutramine on reproductive parameters of male rats were enhanced when the exposure occurred in the dark phase of the l/d cycle, even after a short exposure duration. Our results reinforce the impact of timing on drug therapeutic action.

Effects of isolated or combined exposure to sibutramine and rosuvastatin on reproductive parameters of adult male rats

Many obese patients are exposed to hypolipidemic and serotonin-norepinephrine reuptake inhibitor (SNRI) drugs. Statins are one of the most marketed drugs in the world to treat dyslipidemia, while sibutramine, a SNRI drug, is prescribed in some countries to treat obesity and is detected as an additive in many adulterated weight loss supplements marketed worldwide. Previous studies reported adverse effects of isolated exposure to these drugs on male rat reproductive parameters. In the present work, we further investigated male reproductive toxicity of these drugs, administered in isolation or combination in adult rats for a longer period of treatment. Adult male rats (90 days) were treated (gavage) for 70 days with saline and dimethyl sulfoxide (control), sibutramine (10 mg/kg), rosuvastatin (5 mg/kg), or rosuvastatin combined with sibutramine. Sibutramine alone or with rosuvastatin, promoted a reduction in food intake and body weight gain, weight of the epididymis, ventral prostate and seminal vesicle; as well as decreased sperm reserves and transit time through the epididymis; androgen depletion; and increased index of cytoplasmic droplet. The rosuvastatin-treated group showed reduced frequency of ejaculation. Exposure to this drug alone or combined with sibutramine impaired epididymal morphology. Co-exposed rats had altered epididymal morphometry, and seminal vesicle and testis weights. The rats also showed decreased fertility after natural mating and a trend toward a delay in ejaculation, suggesting a small synergistic effect of these drugs. Given the greater reproductive efficiency of rodents, the results obtained in the present study raise concern regarding possible fertility impairment in men taking statins and SNRI drugs.

Rats undernourished in utero have altered Ca2+ signaling and reduced fertility in adulthood

Epidemiological and animal studies have shown that placental undernutrition impairs reproduction in adult offspring, but the underlying molecular mechanisms within the male genital tract remain unknown. Due to its special physiological characteristics in transport and the modulation of the environment to which its luminal content is exposed, we hypothesized that the vas deferens would be a highly sensitive target. The goals were to investigate whether intrauterine malnutrition affects molecular mechanisms related to Ca(2+)- and oxidative stress-modulated processes and causes structural alterations in the adult rat vas deferens that could attenuate fecundity and fertility. Male adult rats malnourished in utero had increased vas deferens weight associated with thickening of the muscular coat, a decrease in the total and haploid germ cells, a marked increase in the immature cells, and a decline in the numbers of pregnant females and total offspring per male rat. The ex vivo response of vas deferens from malnourished rats demonstrated an accentuated decrease in the contractile response to phenylephrine. The vas deferens had a marked decrease in Ca(2+) transport due to the uncoupling of Ca(2+)-stimulated ATP hydrolysis and ATP-driven Ca(2+) flux, and the downregulation of both sarco-endoplasmic reticulum Ca(2+)-ATPase 2 and the coupling factor 12-kDa FK506-binding protein. An increase in protein carbonylation (a marker of oxidative damage) and an imbalance between protein kinases C and A were observed as a legacy of undernutrition in early life. These results provide the structural and molecular basis to explain at least in part how maternal undernutrition affects fecundity and fertility in adult male rats.

ChemDIS: a chemical-disease inference system based on chemical-protein interactions

Background

The characterization of toxicities associated with environmental and industrial chemicals is required for risk assessment. However, we lack the toxicological data for a large portion of chemicals due to the high cost of experiments for a huge number of chemicals. The development of computational methods for identifying potential risks associated with chemicals is desirable for generating testable hypothesis to accelerate the hazard identification process.

Results

A chemical–disease inference system named ChemDIS was developed to facilitate hazard identification for chemicals. The chemical–protein interactions from a large database STITCH and protein–disease relationship from disease ontology and disease ontology lite were utilized for chemical–protein–disease inferences. Tools with user-friendly interfaces for enrichment analysis of functions, pathways and diseases were implemented and integrated into ChemDIS. An analysis on maleic acid and sibutramine showed that ChemDIS could be a useful tool for the identification of potential functions, pathways and diseases affected by poorly characterized chemicals.

Conclusions

ChemDIS is an integrated chemical–disease inference system for poorly characterized chemicals with potentially affected functions and pathways for experimental validation. ChemDIS server is freely accessible at http://cwtung.kmu.edu.tw/chemdis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13321-015-0077-3) contains supplementary material, which is available to authorized users.

Influence of acute treatment with sibutramine on the sympathetic neurotransmission of the young rat vas deferens

The effects of acute treatment with sibutramine on the peripheral sympathetic neurotransmission in vas deferens of young rats were still not evaluated. Therefore, we carried out this study in order to verify the effects of acute sibutramine treatment on the neuronal- and exogenous agonist-induced contractions of the young rat vas deferens. Young 45-day-old male Wistar rats were pretreated with sibutramine 6 mg/kg and after 4h the vas deferens was used for experiment. The acute treatment with sibutramine was able to increase the potency (pD2) of noradrenaline and phenylephrine. Moreover, the efficacy (Emax) of noradrenaline was increased while the efficacy of serotonin and nicotine were decreased. The maximum effect induced by a single concentration of tyramine was diminished in the vas deferens from treated group. Moreover, the leftward shift of the noradrenaline curves promoted by uptake blockers (cocaine and corticosterone) and β-adrenoceptor antagonist (propranolol) was reduced in the vas deferens of treated group. The initial phasic and secondary tonic components of the neuronal-evoked contractions of vas deferens from treated group at the frequencies of 2 Hz were decreased. Moreover, only the initial phasic component at 5 Hz was diminished by the acute treatment with sibutramine. In conclusion, we showed that the acute treatment with sibutramine in young rats was able to affect the peripheral sympathetic nervous system by inhibition of noradrenaline uptake and reduction of the neuronal content of this neurotransmitter, leading to an enhancement of vas deferens sensitivity to noradrenaline.

Effects of alpha1-adrenoceptor antagonist (tamsulosin) on incident of ejaculation and semen quality in the goat

Male temporary contraception is occasionally required in some animals. Alpha1-adrenoceptor antagonist (tamsulosin) can cause ejaculation disorder. Two sets of Latin square were applied to six male goats to received either normal saline, dimethylsulphoxide or tamsulosin (179.8 nmol kg(-1) ) at 1-week interval. Semen collection and libido scoring were undertaken at 3, 6 and 24 h post-injection. For ejaculated semen, its quality was evaluated. Physiological measurements including body temperature, respiration and heart rates were measured before injection and at 30 min before semen collection. The results showed that libido score and physiological changes were not affected by treatments and time periods. Anejaculation was observed in 11 (91.7%), 5 (41.7%) and 1 (8.3%) males at 3, 6 and 24 h post-tamsulosin injection respectively. The incidence returned to normal when compared with control groups at 24 h. The percentages of motile and live spermatozoa at 6 h post-tamsulosin injection were significantly lower (P < 0.05) than that of normal saline group. At 24 h post-injection, there were no significant differences of all semen parameters among treatments. This study demonstrated that tamsulosin had temporary effects on ejaculation and semen quality without reducing sex desire and physiological functions in male goats.

Slimmer or fertile? Pharmacological mechanisms involved in reduced sperm quality and fertility in rats exposed to the anorexigen sibutramine

Sperm acquire motility and fertility capacity during epididymal transit, under the control of androgens and sympathetic innervations. It is already known that the acceleration of epididymal sperm transit time can lead to lower sperm quality. In a previous work we showed that rats exposed to the anorexigen sibutramine, a non-selective serotonin-norepinephrine reuptake inhibitor, presented faster sperm transit time, lower epididymal sperm reserves and potentiation of the tension of epididymal duct to norepinephrine exposed acutely in vitro to sibutramine. In the present work we aimed to further investigate pharmacological mechanisms involved in these alterations and the impact on rat sperm quality. For this, adult male Wistar rats were treated with sibutramine (10 mg/kg/day) or vehicle for 30 days. Sibutramine decreased final body, seminal vesicle, ventral prostate and epididymal weights, as well as sperm transit time in the epididymal cauda. On the contrary of the in vitro pharmacological assays, in which sibutramine was added directly to the bath containing strips of distal epididymal cauda, the ductal tension was not altered after in vivo sub-chronic exposure to sibutramine. However, there is pharmacological evidence that the endogenous epididymal norepinephrine reserves were reduced in these animals. It was also shown that the decrease in prostate weight can be related to increased tension developed of the gland, due to sibutramine sympathomimetic effects. In addition, our results showed reduced sperm quality after in utero artificial insemination, a more sensitive procedure to assess fertility in rodents. The epididymal norepinephrine depletion exerted by sibutramine, associated with decreases in sperm transit time, quantity and quality, leading to reduced fertility in this experimental model, reinforces the concerns about the possible impact on fertility of man taking sibutramine as well as other non-selective serotonin-norepinephrine reuptake inhibitors, especially considering the lower reproductive efficiency of humans compared to males of other species.

K+ and Cl- channels and transporters in sperm function

To succeed in fertilization, spermatozoa must decode environmental cues which require a set of ion channels. Recent findings have revealed that K(+) and Cl(-) channels participate in some of the main sperm functions. This work reviews the evidence indicating the involvement of K(+) and Cl(-) channels in motility, maturation, and the acrosome reaction, and the advancement in identifying their molecular identity and modes of regulation. Improving our insight on how these channels operate will strengthen our ability to surmount some infertility problems, improve animal breeding, preserve biodiversity, and develop selective and secure male contraceptives.

Could maternal exposure to the antidepressants fluoxetine and St. John's Wort induce long-term reproductive effects on male rats?

Based on the limited number of studies that have investigated the adverse effects of maternal treatment with antidepressants on the development of male descendents, this study was carried out in rat in order to evaluate if maternal exposure to fluoxetine (FLX) or St. John's Wort (SJW) could disrupt the development of male offspring. The dams were treated daily, by gavage, with 7.5 mg/kg of FLX or 100 mg/kg SJW during pregnancy and lactation. The reproductive and behavior parameters were analyzed in male pups. Results showed decreases in the weight of the full seminal vesicle and in the number of spermatozoa. Moreover, FLX-exposed pups presented reduced seminiferous epithelium height and diameter of seminiferous tubules. The present study shows that maternal exposure to FLX, but not SJW could interfere on reproductive parameters in adult male rats.