Hyperprolactinemia affects spermiogenesis in adult male rats

Abstract

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.

Effect of Frankincense (<i>Boswellia thurifera</i>) on Reproductive System in Adult Male Rat

“…This was further confirmed by increased number of spermatocytes (primary and secondary) and spermatids as these stages are completely androgen dependent. [25][26][27] The increased weight and histometry of reproductive organs further prove androgen increase. Significant increase in sperm motility of cauda epididymis was observed in treatment groups.…”

Exposure to bisphenol-A and reproductive hormones among male adults

“…Adjusted prevalence ratio b (95% CI) for > P 75 on hormone parameter Studies in rats indicate that hyperprolactinemia, even when mild to moderate, is known to affect the quality of mature spermatozoa and their fertilizing potential (Aleem et al, 2005). Hyperprolactinemia, thereby, may be associated with male infertility due to either asthenozoospermia, oligozoospermia, or azoospermia (Merino et al, 1997).…”

Assessment of Circulating Hormones in Regulatory Toxicity Studies II. Male Reproductive Hormones

“…Prolactin regulates the number and sensitivity of LH receptors within Leydig cells. Although the evidence is not entirely uniform within a species, increased PRL concentrations have been generally reported to have suppressive effects on GnRH release, T levels, copulatory behavior, and degenerative effects on testicular spermatogenesis in many species, including the rat and man (Aleem et al 2005;Katovich et al 1985;Perryman and Thorner 1981). However, the opposite effect has been demonstrated in the mouse, with increased levels of gonadotropins (LH and FSH), increased copulatory behavior, and enlargement of ASOs (Bartke et al 1987;Wennbo et al 1997).…”