Testicular apoptosis after dietary zinc deficiency: Ultrastructural and TUNEL studies

Abstract

The present study was conducted in Wistar rats to determine whether prepubertal dietary zinc deficiency causes apoptotic changes in testes. Prepubertal male Wistar rats (40–50 gm) were divided into 3 groups: zinc control (ZC), pairfed (PF), and zinc deficient (ZD). Control and pairfed groups were given a 100 ppm zinc diet while the deficient groups received 1 ppm zinc diet for 2 and 4 weeks (w), respectively. Ultrastructural studies revealed several apoptotic features such as wavy basement membrane, displaced nuclei, chromatin condensation, plasma membrane blebbing, nuclear membrane dissolution, loss of inter-Sertoli cell junctional complexes, and intercellular bridges and deformed mitochondria. A variable spectrum of sperm defects had also been visualized e.g., acrosomal deformities such as decapitation and a ring of condensed chromatin around the nuclear periphery, deformed sperm heads with a condensed nucleus, tail-elements with superfluous cytoplasm, and damage to the mitochondrial sheath and aggregation of spermatozoa within the membrane. This was further supported by TUNEL studies. Apoptotic index, epididymal sperm concentration, motility, and fertility index also revealed a significant (P < 0.05) decrease in zinc deficient groups (2 and 4 w) when compared with their respective control and pairfed groups. All the above findings are indicative that changes observed in the testes after dietary zinc deficiency are due to the onset of apoptosis. Increased apoptotic degeneration in testes may cause irreversible changes in the germ cells associated with decreased epididymal sperm concentration, motility, and fertility index which contributes to the low efficiency of spermatogenesis thereby indicating a possible role of zinc in fertility.

Keywords:

• apoptosis
• male fertility
• spermatogenesis
• testes
• zinc deficiency

Acknowledgments

Author Ms. Deepa Kumari, thanks the Department of Science and Technology (DST), Government of Rajasthan, Jaipur [F [5/2] vipro/ DST/ R and D/07-1937] for providing financial assistance, the Department of Zoology, University of Rajasthan, Jaipur [F-41/08/DRS-81/91] for providing Departmental Research Fellowship and the University Grants Commission (UGC), New Delhi [F.4-3/2006 [BSR] 5- 96/2007[BSR] for providing Meritorious Research Fellowship.

Declaration of Interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.