Evaluation Of Reproductive Toxicity Induced By Nicotine Free E-Cigarette Smoke In Pre-Pubertal And Adult Male Rats

Abstract

Background: The three main components of electronic cigarettes (EC) are a cartridge (filled ‎with electronic liquid), atomizer (vaporization chamber), and a rechargeable ‎lithium battery (powerhouse). Variations in e-liquids can be found in nicotine doses as well as types of added ‎flavors. ‎There is growing evidence linking the use of EC to dangerous health ‎consequences, including effects on male and female reproduction. ‎

Aim: To evaluate the male reproductive toxicity of nicotine free E-cigarette smoke on pre-pubertal and adult male Sprague Dawley Albino rats as regard semen analysis, oxidative stress, endocrine disruptive effect and histological changes including effects on blood testes barrier affection.

Methods: To experiment, thirty-two male rats sixteen prepubertal rats and ‎sixteen adult rats were divided into four groups each group consists of ‎eight rats, Group I (Adult control group) and group II (Prepubertal ‎control group) were subjected to inhalation-related stress by exposing ‎them. Group III (Adult EC ‎exposed group) and group IV (Prepubertal EC exposed group) were ‎exposed to vapor generated from EC by using Electrical pump in the ‎inhalation Propylene box (whole body exposure) 3 hours daily for 28 ‎days. The rats were weighed at the start and the end of the experiment. ‎At the end of the 28 days, blood samples were collected to detect ‎the serum levels of testosterone and luteinizing hormone (LH). Oxidative stress markers (SOD and MDA) were assessed. Immunohistochemistry examination included detection of proteins specific for blood testes barrier (occludin and connexin 43).

Results: Testicular weight was significantly increased in the prepubertal, and adult control groups compared to the prepubertal and adult exposed groups respectively. Prepubertal EC exposed group had a significantly lower percentage of sperm motility, and a significantly increased percentage of abnormal sperm morphology compared to the adult EC exposed group. The testosterone level was significantly lower in prepubertal and adult exposed groups with significant increase in LH level. A significant decrease in SOD activity as antioxidant defense mechanism was observed in EC exposed groups. Prepubertal and adult EC exposed groups showed significant increased expression of connexin in line with decreased occludin immune staining compared to controls.

Conclusion: The present study confirmed the reproductive toxic effect of nicotine free EC vapor on pre-pubertal and adult male Sprague Dawley rats as regard endocrine disruptive effects, semen abnormalities, testicular histological changes and testicular oxidative stress. The study also clarified the toxic effect of EC smoking on proteins of blood testes barrier particularly, (occludin and connexin 43).