Antifertility effects of fluphenazine in adult male rats

Prolactin inhibitor changes testosterone production, testicular morphology, and related genes expression in cashmere goats

Prolactin has multifaceted roles in lactation, growth, metabolism, osmoregulation, behavior, and the reproduction of animals. This study aimed to investigate the involvement of prolactin in testicular function in cashmere goats. Twenty cashmere goats were randomly assigned to either the control group (CON) or the bromocriptine treatment group (BCR, bromocriptine, prolactin inhibitor). Blood and testis samples collected for analysis after 30 days of treatment. The results indicated that, compared with the CON group, BCR significantly decreased (p < 0.05) the serum concentrations of prolactin, and significantly increased (p < 0.05) the levels of testosterone and luteinizing hormone (LH) on day 30. The serum level of the follicle-stimulating hormone (FSH) was not affected (p > 0.05) by the treatment. The mean seminiferous tubule diameter and spermatogenic epithelium thickness were increased (p < 0.05) in the BCR group. Subsequently, we performed RNA sequencing and bioinformatics analysis to identify the key genes and pathways associated with the regulation of spermatogenesis or testosterone secretion function. A total of 142 differentially expressed genes (DEGs) were identified (91 were upregulated, 51 were downregulated). Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed that the DEGs were mainly involved in the extracellular matrix (ECM), hippo, and steroid hormone biosynthesis, which are related to testicular function. The expression of the genes SULT2B1, CYP3A24, and CYP3A74 in the steroid hormone biosynthesis pathway significantly increased (p < 0.05) in the BCR group, which was validated by qRT-PCR. These results provide a basis for understanding the mechanisms underlying the regulation of testicular function by prolactin in cashmere goats.

Hindlimb unloading-induced reproductive suppression via Downregulation of hypothalamic Kiss-1 expression in adult male rats

BACKGROUND

Spaceflights-induced microgravity can alter various physiological processes in human's body including the functional status of the reproductive system. Rodent model of tail-suspension hindlimb unloading is extensively used to stimulate the organs responses to the microgravity condition. This study explores the potential effects of hindlimb unloading on testicular functions and spermatogenesis in adult male rats and the underlying mechanism/s.

METHODS

Twenty Sprague-Dawley rats were allotted into two groups: normally loaded group (control; all arms were in touch with the grid floor) and hindlimb unloaded group (HU; only the forearms were in contact with the grid floor).

RESULTS

Following 30 days of exposure, the HU group saw a decline in body weight, testicular and epidydimal weights, and all semen parameters. The circulating concentrations of gonadotropin-releasing hormone (GnRH), follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone significantly decreased, while levels of kisspeptin, corticosterone, inhibin, prolactin and estradiol (E2) increased in the HU group. Intratesticular levels of 5α-reductase enzyme and dihydrotestosterone (DHT) were suppressed, while the levels of aromatase and kisspeptin were significantly elevated in the HU group. Hypothalamic kisspeptin (Kiss1) mRNA expression levels were downregulated while its receptors (Kiss1R) were upregulated in the HU group. On the contrary, the mRNA expression levels of testicular Kiss1 were upregulated while Kiss1R were downregulated. The pituitary mRNA expression levels of FSHβ and LHβ decreased in the HU group. The levels of the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and nitric oxide (NO) concentrations, and total antioxidant capacity (TAC) were elevated while malondialdehyde (MDA) concentrations declined in the testes of HU group. The testes of the HU rats showed positive immunostaining of caspase-3, heat shock protein 70 (HSP70) and Bcl2.

CONCLUSIONS

Altogether, these results revealed an inhibitory effect of hindlimb unloading on kisspeptin signaling in the hypothalamic-pituitary-testicular axis with impaired spermatogenesis and steroidogenesis.

Risperidone induced reproductive toxicity in male rats targeting leydig cells and hypothalamic-pituitary-gonadal axis by inducing oxidative stress

Risperidone (RIS), a commonly used drug during a lifetime for the treatment of schizophrenia, causes some adverse effects in the male reproductive system; however, there is no comprehensive reproductive toxicity study of RIS. For this purpose, male rats were administered orally for 1.25, 2.5 and 3 mg/kg RIS for 28 days and the sperm count, motility, morphology, DNA damage and the histological changes in testicular tissue were evaluated. Follicle-stimulating hormone (FSH), luteinising hormone (LH) and serum levels of testosterone, which are the main hormonal regulators of reproduction, and testicular glutathione (GSH), catalase (CAT), superoxide dismutase (SOD) and malondialdehyde (MDA) levels as the indicators of oxidative stress were determined. Normal sperm morphology was decreased in RIS groups and histopathological degeneration occurred in testis tissue dose-dependently. Serum LH levels were not altered; however, FSH and testosterone levels decreased in the high-dose group. Histopathologic examination showed RIS toxicity targeted Leydig cells, which might be associated with impairment of the hypothalamic-pituitary-gonadal (HPG) axis. GSH levels were decreased and MDA levels were increased in the high-dose group which was evaluated as indicators of oxidative stress. In conclusion, RIS caused reproductive toxicity in male rats by inducing oxidative stress and disrupting hormonal regulation.

The adverse effects of psychotropic drugs as an endocrine disrupting chemicals on the hypothalamic-pituitary regulation in male

Adverse effects of drugs on male reproductive system can be categorized as pre-testicular, testicular, and post-testicular. Pre-testicular adverse effects disrupt the hypothalamic-pituitary-gonadal (HPG) axis, generally by interfering with endocrine function. It is known that the HPG axis has roles in the maintenance of spermatogenesis and sexual function. The hypothalamus secretes gonadotropin-releasing hormone (GnRH) which enters the hypophyseal portal system to stimulate the anterior pituitary. The anterior pituitary secretes gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) which are vital for spermatogenesis, into the blood. The FSH stimulates the Sertoli cells for the production of regulatory molecules and nutrients needed for the maintenance of spermatogenesis, while the LH stimulates the Leydig cells to produce and secrete testosterone. Many neurotransmitters influence the hypothalamic-pituitary regulation, consequently the HPG axis, and can consequently affect spermatogenesis and sexual function. Psychotropic drugs including antipsychotics, antidepressants, and mood stabilizers that all commonly modulate dopamine, serotonin, and GABA, can affect male spermatogenesis and sexual function by impairment of the hypothalamic-pituitary regulation, act like endocrine-disrupting chemicals. Otherwise, studies have shown the relationship between decreased sperm quality and psychotropic drugs treatment. Therefore, it is important to investigate the adverse reproductive effects of psychotropic drugs which are frequently used during reproductive ages in males and to determine the role of the hypothalamic-pituitary regulation axis on possible pathologies.

Access to the CNS: Biomarker Strategies for Dopaminergic Treatments

Despite substantial research carried out over the last decades, it remains difficult to understand the wide range of pharmacological effects of dopaminergic agents. The dopaminergic system is involved in several neurological disorders, such as Parkinson's disease and schizophrenia. This complex system features multiple pathways implicated in emotion and cognition, psychomotor functions and endocrine control through activation of G protein-coupled dopamine receptors. This review focuses on the system-wide effects of dopaminergic agents on the multiple biochemical and endocrine pathways, in particular the biomarkers (i.e., indicators of a pharmacological process) that reflect these effects. Dopaminergic treatments developed over the last decades were found to be associated with numerous biochemical pathways in the brain, including the norepinephrine and the kynurenine pathway. Additionally, they have shown to affect peripheral systems, for example the hypothalamus-pituitary-adrenal (HPA) axis. Dopaminergic agents thus have a complex and broad pharmacological profile, rendering drug development challenging. Considering the complex system-wide pharmacological profile of dopaminergic agents, this review underlines the needs for systems pharmacology studies that include: i) proteomics and metabolomics analysis; ii) longitudinal data evaluation and mathematical modeling; iii) pharmacokinetics-based interpretation of drug effects; iv) simultaneous biomarker evaluation in the brain, the cerebrospinal fluid (CSF) and plasma; and v) specific attention to condition-dependent (e.g., disease) pharmacology. Such approach is considered essential to increase our understanding of central nervous system (CNS) drug effects and substantially improve CNS drug development.

Psychotropics and Male Reproduction

Psychotropic drugs, including antidepressants, antipsychotics, and anticonvulsants, all have negative effects on sexual function and semen quality. These adverse events vary among men and are less pronounced for some medications, allowing their effects to be managed to some extent. Use of specific serotonin reuptake inhibitors (SSRIs) is prevalent in men of reproductive age; and application to treat premature ejaculation increases the number of young men on SSRI therapy. Oxidative damage to sperm can result from prolonged residence in the male reproductive tract. The increase in ejaculatory latency seen with SSRIs likely underlies some of their negative effects on semen quality, including higher sperm DNA fragmentation, seen in all SSRIs evaluated thus far. These medications increase prolactin (PRL) levels in some men, and this is often credited with inhibitory effects on male reproduction; however, testosterone levels are generally normal, reducing the likelihood of direct HPG axis inhibition by PRL. The tricyclic antidepressants have also been shown to increase PRL levels in some studies but not in others. The exception is the tricyclic antidepressant clomipramine, which profoundly increases PRL levels and may depress semen quality. Other antidepressants modulating synaptic levels of serotonin, norepinephrine, and/or dopamine may have toxicity similar to SSRIs, but most have not been evaluated. In limited studies, norepinephrine-dopamine reuptake inhibitors (NDRIs) and serotonin agonist/reuptake inhibitors (SARIs) have had minimal effects on PRL levels and on sexual side effects. Antipsychotic medications increase PRL, decrease testosterone, and increase sexual side effects, including ejaculatory dysfunction. The greatest evidence is for chlorpromazine, haloperidol, reserpine, risperidone, and thioridazine, with less effects seen with aripiprazole and clozapine. Remarkably few studies have looked at antipsychotic effects on semen quality, and this is an important knowledge gap in reproductive pharmacology. Lithium increases PRL and LH levels and decreases testosterone although this is informed by few studies. The anticonvulsants, many used for other indications, generally decrease free or bioavailable testosterone with variable effects on the other reproductive hormones. Valproate, carbamazepine, oxcarbazepine, and levetiracetam decrease semen quality; other anticonvulsants have not been investigated for this adverse reaction. Studies are required evaluating endpoints of pregnancy and offspring health for psychotropic medications.

Putative molecular mechanism underlying sperm chromatin remodelling is regulated by reproductive hormones

Background

The putative regulatory role of the male reproductive hormones in the molecular mechanism underlying chromatin condensation remains poorly understood. In the past decade, we developed two adult male rat models wherein functional deficits of testosterone or FSH, produced after treatments with 20 mg/Kg/d of cyproterone acetate (CPA) per os, for a period of 15 days or 3 mg/Kg/d of fluphenazine decanoate (FD) subcutaneously, for a period of 60 days, respectively, affected the rate of sperm chromatin decondensation in vitro. These rat models have been used in the current study in order to delineate the putative roles of testosterone and FSH in the molecular mechanism underlying remodelling of sperm chromatin.

Results

We report that deficits of both testosterone and FSH affected the turnover of polyubiquitylated histones and led to their accumulation in the testis. Functional deficits of testosterone reduced expression of MIWI, the 5-methyl cap binding RNA-binding protein (PIWIlike murine homologue of the Drosophila protein PIWI/P-element induced wimpy testis) containing a PAZ/Piwi-Argonaut-Zwille domain and levels of histone deacetylase1 (HDAC1), ubiquitin ligating enzyme (URE-B1/E3), 20S proteasome α1 concomitant with reduced expression of ubiquitin activating enzyme (ube1), conjugating enzyme (ube2d2), chromodomain Y like protein (cdyl), bromodomain testis specific protein (brdt), hdac6 (histone deacetylase6), androgen-dependent homeobox placentae embryonic protein (pem/RhoX5), histones h2b and th3 (testis-specific h3). Functional deficits of FSH reduced the expression of cdyl and brdt genes in the testis, affected turnover of ubiquitylated histones, stalled the physiological DNA repair mechanism and culminated in spermiation of DNA damaged sperm.

Conclusions

We aver that deficits of both testosterone and FSH differentially affected the process of sperm chromatin remodelling through subtle changes in the ‘chromatin condensation transcriptome and proteome’, thereby stalling the replacement of ‘dynamic’ histones with ‘inert’ protamines, and altering the epigenetic state of condensed sperm chromatin. The inappropriately condensed chromatin affected the sperm chromatin cytoarchitecture, evident from subtle ultrastructural changes in the nuclei of immature caput epididymal sperm of CPA- or FD-treated rats, incubated in vitro with dithiothreitol.

Prolactin and male fertility: the long and short feedback regulation

In the last 20 years, a pituitary-hypothalamus tissue culture system with intact neural and portal connections has been developed in our lab and used to understand the feedback mechanisms that regulate the secretions of adenohypophyseal hormones and fertility of male rats. In the last decade, several in vivo rat models have also been developed in our lab with a view to substantiate the in vitro findings, in order to delineate the role of pituitary hormones in the regulation of fertility of male rats. These studies have relied on both surgical and pharmacological interventions to modulate the secretions of gonadotropins and testosterone. The interrelationship between the circadian release of reproductive hormones has also been ascertained in normal men. Our studies suggest that testosterone regulates the secretion of prolactin through a long feedback mechanism, which appears to have been conserved from rats to humans. These studies have filled in a major lacuna pertaining to the role of prolactin in male reproductive physiology by demonstrating the interdependence between testosterone and prolactin. Systemic levels of prolactin play a deterministic role in the mechanism of chromatin condensation during spermiogenesis.

Estradiol affects androgen-binding protein expression and fertilizing ability of spermatozoa in adult male rats

The estrogenicity of certain environmental pollutants is being increasingly correlated to decline in sperm counts and fertility of the males. Qualitative effects, if any, of estrogen(s) on terminal differentiation of spermatids have been less reported. The present study suggests that exposure to estrogen(s) can also alter the status of condensed chromatin in testicular spermatozoa and reduce their fertilizing potential. A significant reduction was evident in the serum gonadotropins, testosterone, weights of reproductive organs, sperm counts and litters sired by male rats after 10 days of estradiol exposure to a dose of 0.1mg/kg/day. Estradiol treatment led to retardation of in vitro decondensation rates of sperm chromatin, reduction in the uptake of acridine orange dye by chromatin, reduction in susceptibility of chromatin to acid denaturation in vitro, reduced uptake of thiol reactive monobromobimane dye and reduced levels of immunoreactive protamine 1 in caput epididymal sperms. Concomitantly, testicular levels of immunoreactive protamine 1, transition proteins 1/2 and cyclic adenosyl response element modulator-tau (CREMtau) were significantly reduced whilst their mRNA levels were unaffected after estradiol treatment. A significant increase was observed in the testicular mRNA levels of androgen-binding protein (ABP) in estradiol treated sires. An inverse correlation was observed between ABP mRNA levels and uptake of acridine orange by estradiol treated caput sperm chromatin. The results suggest that estradiol-induced increase in ABP mRNA underlies the mechanism(s) involved in the reduction in levels of certain proteins involved in nuclear chromatin condensation during spermiogenesis.

Cyproterone acetate affects protamine gene expression in the testis of adult male rat

The temporal effects of oral administration of cyproterone acetate (CPA), a progestational androgen receptor blocker, were studied on the fertility of adult male rat sires, at a dose of 20 mg kg-1 day-1 after 15 days of gavage. The treatment reduced the fertility and weights of accessory sex glands, without altering the serum levels of luteinizing hormone, follicle-stimulating hormone (FSH) and testosterone (T). Sperm counts were significantly reduced after treatment. Several changes were evident in caput epididymal sperm chromatin in treated rats. The in vitro decondensation rates of sperm chromatin and total fluorescent acridine orange (AO) dye uptake were enhanced. The fluorescent AO dye uptake by the double- and single-stranded sperm chromatin increased. The uptake of thiol-specific monobromobimane fluorescent dye by sperm chromatin was significantly reduced. Sperm of treated rats exhibited hypoprotamination. Protamine levels in the testis were significantly reduced after treatment. Androgen-binding protein (ABP) expression was significantly reduced in testis after treatment. A slight but significant increase was observed in cyclic AMP immunoexpression in testis after treatment. The expression and levels of transition proteins 1 (TP1) and 2 (TP2) as well as cyclic AMP response element modulator protein-tau were maintained at control levels in the testis of treated rats. The present study reports that androgen receptor occupation by CPA preferentially reduces the levels of spermatidal protamine in testis and spermatozoa involved in nuclear chromatin condensation. It is inferred that ABP could be mediating the effects of T in modulating the sequential expression of TPs and protamines during nuclear chromatin condensation. It is likely that indirect effects of T involve its aromatization in spermatids.

Effects of tamoxifen citrate on gene expression during nuclear chromatin condensation in male rats

AIM

To evaluate the effects of tamoxifen citrate on gene expression during nuclear chromatin condensation in male rats.

METHODS

The effects of an oral dose of 0.4 kg/(kg.d) tamoxifen citrate on rates of in vitro chromatin decondensation, acridine orange (AO) dye uptake, concentration of thiol-groups, levels and/or expression of transition proteins 1, 2 (TP1, TP2), protamine 1 (P1), cyclic AMP response element modulator-tau (CREMtau), androgen-binding protein (ABP) and cyclic adenosine 3',5' monophosphate (cAMP) were evaluated after 60 days of exposure in adult male rats. Controls received the vehicle.

RESULTS

Tamoxifen citrate enhanced the rates of chromatin decondensation, increased AO dye uptake and reduced free thiols in caput epididymal sperms and reduced the levels of TP1, TP2, P1, and CREMtau in the testis, while cAMP was unaffected. P1 deposition was absent in the sperm. The transcripts of TP1, TP2 were increased, of P1 and ABP decreased, while those of CREMtau unaffected in the testis.

CONCLUSION

Tamoxifen citrate reduced caput epididymal sperm chromatin compaction by reducing the testicular levels of proteins TP1, TP2 and P1 and the CREMtau involved in chromatin condensation during spermiogenesis. Tamoxifen citrate affects the expression of these genes at both the transcriptional and post-transcriptional levels.

Effect of high intratesticular estrogen on the seminiferous epithelium in adult male rats

The presence of estrogen receptor beta and aromatase in the germ cell has highlighted the physiological role of the traditionally female hormone, estrogen, in spermatogenesis. Estrogen receptor alpha knockouts and aromatase knockouts have further accentuated the role of estrogen in germ cell maturation. To delineate the direct action of estrogen in the seminiferous epithelium, we studied the effects of high intratesticular estradiol. The study was based on the fact that administration of exogenous estradiol suppresses the hypothalamus pituitary gonadal axis (HPG) with a dose-dependant concomitant increase in intratesticular estrogen levels. Three doses of 17-beta estradiol, namely 20, 100 and 200 microg/kg/day were administered subcutaneously to different batches of adult male rats for 10 days. The effect of the three doses on serum hormonal profile, intratesticular testosterone (T) and estradiol (E) levels were studied. Twenty micrograms per kilograms per day of 17-beta estradiol affected the hypothalamus-pituitary axis, reducing serum gonadotropins and intratesticular testosterone; however, 100 microg/kg/day of 17-beta estradiol decreased serum FSH and intratesticular testosterone, increased intratesticular estradiol, but had no effect on serum LH. Interestingly, 200 microg/kg/day of 17-beta estradiol decreased serum and intratesticular T without any effect on serum gonadotropins. This could be attributed to the positive feedback effect of estrogens on gonadotropins. In the testis, morphologically two visible effects were seen, namely 'spermiation failure' in all three doses attributed to the suppression of T and FSH and a 'maintenance effect' in the 100 microg/kg/day attributed to E and/or 10% of available intratesticular T. The direct effect of an increase in intratesticular estradiol levels was observed in terms of a decrease in apoptosis in germ cell. The study, therefore, suggests that 100 microg/kg/day of 17-beta estradiol could be used to study the effects of high intratesticular estradiol with a concomitant decrease in intratesticular T and serum FSH levels on spermatogenesis.

Hyperprolactinemia affects spermiogenesis in adult male rats

The mechanisms underlying the antifertility effects of hyperprolactinemia have yet to be established in an appropriate experimental model. Hyperprolactinemia is a known side effect of fluphenazine, a broad spectrum, long-acting phenothiazine known to be dopamine type-D2 receptor antagonist. In our earlier study in adult male rats, we reported that fluphenazine at a dose of 3 mg/kg/day suppressed serum FSH but not testosterone (T) through increasing dopamine (DA) metabolism in the pituitary gland, within 60 days. Fluphenazine treatment affected sperm quality and male rats treated with fluphenazine sired fewer litters. The effects of fluphenazine-induced hyperprolactinemia on sperm quality appeared to be related to reduced FSH. We now report that FSH suppression enhanced the uptake of acridine orange (AO), a DNA intercalating, fluorescent dye by the fluphenazine-treated caput epididymal sperms with concomitant reduction in the uptake of thiol-specific monobromobimane (mBBr) fluorescent dye in vitro, suggesting greater accessibility of DNA intercalating dye to sperm chromatin and reduction in free sperm protein thiols. The concomitant increase in AO and decrease in mBBr fluorescence was suggestive of loose chromatin packaging in caput epididymal sperms after treatment with fluphenazine at 3 mg/kg/day for 60 days. The suppression in levels of protamine (P1) in caput epididymal sperms suggested that chromatin hypocompaction was due to reduced deposition of protamines in sperm chromatin. Reduction in testicular levels of cyclic adenosyl 3', 5' monophosphate response element modulator (CREMtau) and P1 further suggested that reduced deposition was indeed due to reduced synthesis. The concomitant reduction in testicular levels of transition protein 1 (TP1) and transition protein 2 (TP2) also suggested that hypoprotamination was due to reduced synthesis of these proteins crucial for facilitating P1 deposition. The effect appeared to have occurred at the level of translation of CREMtau, since its transcript levels were unaffected whereas those of TP1, TP2 and P1 and protamine were upregulated. The study led to the view that the effects of FSH suppression were manifest on the posttranscriptional modifications of CREMtau, as also on transcript repression of TP1, TP2, P1, which do the RNA- binding proteins bring about. Reduction in FSH did not decrease ABP expression in the testis, which has recently been implicated in the expression of transition protein 1 in vitro. However, a significant reduction was evident after fluphenazine treatment, in the immunoexpression of testicular cAMP, the mediator of FSH effects in the Sertoli cells and putative mediator of ABP effects in the spermatids. The study suggests that fluphenazine-induced hyperprolactinemia suppressed FSH and affected a putative cAMP-dependent mechanism underlying posttranscriptional modification of spermatidal genes involved in chromatin condensation, presumably by reducing the availability/secretion of ABP, a paracrine regulator of spermiogenesis in vitro.