Role of Zinc in Reproductive Biology - An Overview

Review Article

Austin J Reprod Med Infertil. 2015;2(2): 1009.

Role of Zinc in Reproductive Biology - An Overview

Murarka S1, Mishra V², Joshi P² and Kumar Sunil¹*

¹Division of Reproductive and Cytotoxicology, National Institute of Occupational Health (ICMR), Ahmedabad, India

²Department of Obstetrics and Gynecology, Institute of Kidney Diseases, Civil Hospital Campus, Ahmedabad, India

*Corresponding author: Kumar Sunil, Scientist ‘G’, Division of Reproductive and Cytotoxicology, National Institute of Occupational Health (ICMR), Ahmedabad-380016, India

Received: April 01, 2015; Accepted: May 20, 2015; Published: May 21, 2015

Abstract

Trace amount of certain metals including zinc are essential for the normal growth, development, reproduction and various other physiological functions in the body. However, their appropriate amount is needed for maintaining steady state mechanism of various functions in the body. Some of the heavy metals even at a very low level are having toxic potential, which might be dependent upon the dose, time and duration of exposure as well as factors associated with host. The available data on zinc level in serum and seminal plasma suggests that zinc has a significant role in spermatogenesis and maintaining the total number of sperms as well as sperm motility and DNA integrity etc. However, significantly higher level (several times of normal level) of zinc may have adverse effects on sperm quality. Zinc is also essential for female reproductive system including embryogenesis and development. Thus deficiency or excess of zinc level might have significant impact on sperm and egg physiology. Zinc has also been involved in antagonizing the effect of various toxicants. Further, data also point the role of zinc supplementation may be useful as one of the adjuvant components for the subjects having sub normal reproductive function with lower seminal zinc level. However, more research is needed on this aspect, as some of the conflicting data also existed.

Keywords: Zinc; Reproduction; Spermatogenesis; Sperm motility; Sperm concentration

Introduction

Human beings as well as aquatic and wild life species are exposed to certain metals and their oxides, through various sources. Some of these metals are toxic to health including reproductive health and few are essential in trace amount for various physiological functions of the body. Thus trace amount of these assisting in maintaining health of various organ systems. All the stages of spermatogenesis and oogenesis would be the potent target of chronic exposure to even low doses of toxic metals. Zinc is reported to be necessary for DNA replication, RNA polymerases, protein synthesis and various metabolic processes. The cell replication, protein synthesis and growth processes etc. are reported to be to some extent dependent upon zinc [1]. Further, zinc is also included in many nutritional supplements [2]. Zinc is a vital trace element found in small amounts in a variety of cells and tissues of organisms and it is a cofactor of more than 300 enzymes reported by Tapiero and Tew [3], and zinc is also involved in several cell functions including signal transduction, transcription and also replication [4]. Further, it has been reported that about three to ten percent of all proteins in mammalian genomes are considered to bind zinc for holding, activity and conformational changes [5].

It is known that the adult human body have about 1–3 g of zinc, and about 0.1% of which is replenished daily [6]. Zinc is recognized as an essential food element required by the body in trace amounts. It is also known that very little zinc in the diet can lead to poor health, reproductive problems, and lowered ability to resist against disease and lot of zinc in diet may also be unfavorable to health [7]. Higher doses of zinc also have the cyto-toxic potential in mice reported by Gupta et al. [8]. Further, the level of zinc that bring health impairments are much higher than the Recommended Dietary Allowances (RDAs) i.e. 11 and 8 mg/day zinc for men and women respectively. If 10-15 times of RDA of zinc are taken even for a short time, it may lead to stomach cramps, nausea, and vomiting. Further, ingesting high levels of zinc for several months may lead to anemia, damage pancreas, and decrease levels of high-density lipoprotein (HDL) cholesterol [9]. It is known that both animals and humans are needed to produce healthy sperm and ova for continuing their species on this earth. This needs formation and maturation of spermatozoa, ova, fertilization, development and production of offspring. In order to achieve this, number of exogenous and endogenous favorable conditions is necessary for the successful of reproductive outcome for the continuation of the species. In this communication, an attempt has been made by analyzing the data available, on zinc and reproduction in order to understand the role of zinc in reproduction.

Material and Methods

In the present paper authors has tried to provide a current status on the role of zinc in reproduction. Searching various databases such as Pub Med, Toxline, Google and certain other websites as well as consulting various journals on reproduction and metal toxicology, assimilated the literature and made certain observations and conclusions. The paper is divided in to four broad headings based on the data available on human male and female reproduction along with relevant experimental studies, its role in in vitro fertilization and oocyte maturation and also data pertaining to understand the mechanism of alterations and preventive potential of zinc against certain reproductive toxicants is also discussed. The data on seminal zinc levels with respect to various seminal parameters has been depicted in Table1.

Citation: Murarka S, Mishra V, Joshi P and Kumar Sunil. Role of Zinc in Reproductive Biology - An Overview.Austin J Reprod Med Infertil. 2015;2(2): 1009. ISSN:2471-0393