Journal of Endocrinology and Reproduction

Ajit Kumar Navin ¹, Navaneethabalakrishnan Shobana ¹, Sankar Venkatachalam ², Mohammad Abdulkader Akbarsha ³, Sakhila K. Banu ⁴, Mariajoseph Michael Aruldhas ⁵

Affiliations
1 Department of Endocrinology, Dr. A.L.M. Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Taramani-Velachery Link Road, Chennai – 600113, Tamil Nadu, IN
2 Department of Anatomy, Dr. A.L.M. Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Taramani-Velachery Link Road, Chennai – 600113, Tamil Nadu, IN
3 Life Sciences, National College (Autonomous), Tiruchirappalli – 620001, Tamil Nadu, IN
4 Department of Veterinary Integrative Biosciences, Texas A & M University, Texas, US
5 Department of Endocrinology, Dr. A.L.M. Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Taramani-Velachery Link Road, Chennai – 600113, IN

Abstract

Chromium (Cr), an essential trace element, turns into an endocrine disruptor and male reproductive toxicant when its concentration in drinking water exceeds the safe limit. Improper disposal of effluents from more than 50 industries that use Cr contaminate the environment, in addition to occupational exposure of the workers. Testis has come to stay as a target for the reproductive toxicity of hexavalent Cr (CrVI), whereas its impact on fetal testicular differentiation remains elusive. We tested the hypothesis “In utero exposure to CrVI may alter the level of specific proteins controlling differentiation of testicular cell types”. Pregnant Wistar rats were exposed to drinking water containing 50, 100 and 200 ppm potassium dichromate (CrVI) during gestational days 14 to 21, covering the period of fetal differentiation of testicular cells. Testes were collected on postnatal day 1 and subjected to light microscopic histological studies and immunohistochemical detection of cell-specific proteins. Testis of neonatal rats with gestational exposure to high doses of CrVI showed shrunken and dispersed tubules with fewer gonocytes, extensive vacuolization of seminiferous cord accompanied by damaged epithelium, and shrunken Leydig cells present in large interstitial spaces and loose compaction of cells when compared coeval control group. Immunosignals of androgen and estrogen receptor β increased, whereas those of estrogen receptor α, follicle stimulating hormone receptor, anti-Mullerian hormone, P₄₅₀ aromatase, inhibin, c-fos and c-jun decreased. Immunosignals of steroidogenic acute regulatory protein and CYP11A1 increased, whereas 3β - hydroxy steroid dehydrogenase and CYP17A1 proteins decreased, indicating compromised steroidogenic function. Our findings support the proposed hypothesis and we conclude that gestational exposure to CrVI disrupts specific hormones and hormone receptors that control fetal differentiation of testicular cells. The detrimental effect of gestational exposure to CrVI on functional differentiation of testicular cells may have a bearing on testicular function at adulthood.

Keywords

Gonocytes, Leydig Cell, Sertoli Cell, Steroidogenesis, Testis.

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Sadhasivam Balaji ¹, Sadhasivam Balaji ², Navaneethabalakrishnan Shobana ¹, Navaneethabalakrishnan Shobana ³, Ajit Kumar Navin ¹, Ajit Kumar Navin ⁴, Jaganathan Anbalagan ¹, Jaganathan Anbalagan ⁵, Bhaskaran Ravi Sankar ¹, Ramachandran Ilangovan ¹, Mariajoseph Michael Aruldhas ¹

Affiliations
1 Department of Endocrinology, Dr. A.L.M. Post-Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai – 600113, India ., IN
2 Department of ORAL Head and Neck Surgery, The University of Oklahoma Health Sciences Center, RP800, Research Parkway Suite 432, Oklahoma City – 73104, Oklahoma, USA ., IN
3 Department of Medical Physiology, College of Medicine, Texas A & M Health Science Center, Bryan Campus, Texas – 77807, USA ., IN
4 Department of Pharmaceutical Sciences, Irma Lerma Rangel College of Pharmacy, Texas A and M Health Science Center, Reynolds Medical Building, College Station, Texas – 77843, USA ., IN
5 One Bungtown Road, James Building, Cold Spring Harbor Laboratories, New York – 11724, USA ., IN

Abstract

Purpose: Hypothyroidism is associated with infertility. We have reported that gestational-onset hypothyroidism impairs post-testicular sperm maturation in F1 progeny rats, whereas the underlying mechanism remains obscure. In this study, we tested the hypothesis “transient gestational-onset hypothyroidism affects post-testicular sperm maturation by inducing oxidative stress and modifying the expression of specific genes controlling epididymal function in F1 progeny rats”. Methods: Hypothyroidism was induced by providing 0.05% methimazole in drinking water to pregnant rats during specific periods of foetal differentiation of testis and epididymis. On the postnatal day 120, epididymes were dissected out and used for various analyses. Sperm parameters and activities of antioxidants and pro-oxidants were assayed using standard protocols. qRT-PCR and western blot were carried out to assess the expression of epididymal functional genes and their respective proteins. Results: Gestational-onset hypothyroidism produced decrease of sperm motility and membrane integrity, and increase of abnormal sperm morphologies. While the concentration of reduced glutathione and specific activities of antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase decreased, levels of pro-oxidants hydrogen peroxide and lipid peroxidation increased. Expression levels of androgen and thyroid hormone receptors α/β, aquaporin 9, and glutathione peroxidise 5 decreased, whereas estrogen receptors α/β increased in rats with gestational-onset hypothyroidism. Conclusion: Our results support our hypothesis and we conclude that gestationalonset hypothyroidism impairs post-testicular sperm maturation due to oxidative stress and modified expression of nuclear hormone receptors and aquaporin 9 in the epididymis of F1 progeny .

Keywords

Androgen Receptor, Antioxidants, Aquaporin 9, Estrogen Receptors, Thyroid Hormone Receptor

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