- Title
- Investigating the effects of mobile phone radiation and heating on spermatogenesis and sperm function
- Creator
- Houston, Brendan
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2018
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Male infertility is a common issue affecting 7% of the population, and recent emphasis has been placed on the involvement of environmental pressures in eliciting or exacerbating this condition. We live in a world where we are ubiquitously exposed to radiofrequency electromagnetic radiation (RF-EMR), emitted from a variety of electronic devices for the purpose of communication. The biological effects of this radiation are under active debate due to the absence of a widely supported cellular mechanism of action that could account for the inconsistent experimental outcomes documented in response to RF-EMR exposure. However, a growing body of evidence suggests that RF-EMR may act as a stimulator of cellular oxidative stress. In a similar context, we are now also experiencing warmer climates in line with a state of global warming, and it is known that heat is capable of negatively affecting the sensitive physiological environment of the mammalian male reproductive system. While oxidative stress has similarly been implicated in this pathology, the complete reproductive consequences of heating the male reproductive system are not fully understood. The collective studies described in this thesis were formulated to address the overarching hypothesis that environmental exposures are capable of eliciting a state of oxidative stress within the male reproductive system, particularly affecting the spermatozoa produced under these conditions and leading to impaired male reproductive health. Furthermore, it was hypothesized that the physical factors investigated in this thesis were acting upon the mitochondria of male germ cells and spermatozoa to induce this stress. Accordingly, my specific aims were to dissect the mechanisms by which RF-EMR and environmental heating affect sperm quality, and particularly to advance our understanding of how RF-EMR interacts with biological systems and cells. Through studying the effects of RF-EMR and ambient temperature heating on the male reproductive tract, we add weight to the concept that the male reproductive system is sensitive to such a state of oxidative stress. We have identified important mechanistic features accounting for the pathology of these stresses. Here, we exposed isolated murine male germ cells and spermatozoa to RF-EMR, which supported our hypothesis that this insult targets the mitochondria of these cells, resulting in the generation of mitochondrial ROS, a subsequent state of oxidative stress and reduced sperm quality. Similarly, when whole body heating was used as the insult, spermatozoa were compromised in their motility and membrane integrity in association with elevated ROS originating from the mitochondria. Furthermore, with both heating and RF-EMR exposure, sperm oxidative DNA damage was significantly elevated. We have also generated evidence to support Complex III of the mitochondrial electron transport chain as a likely target of RF-EMR in male germ cells. Our understanding of this mechanism will direct future studies, where it will be important to focus on multigenerational approaches conducted at real-life exposure levels, to gain further understanding of the clinical effects of RF-EMR. With respect to ambient temperature heating, the round spermatids were particularly susceptible, but also spermatocytes, proliferating spermatogonia and spermatozoa exhibited susceptibility to this form of stress; whereas this was not the case for spermatogonial stem cells. However, the spermatozoa produced under both insults were readily capable of undergoing capacitation and fertilizing oocytes in an in vitro setting. Furthermore, the resulting embryos were not overtly inhibited in their early embryonic development. Nevertheless, such findings do not discount the possibility that damaged spermatozoa may have been excluded from the fertilization cascade in favour of their undamaged counterparts. Alternatively, it is possible that the consequences of these insults will present themselves at a later point in development, thus providing a clear imperative to conduct detailed exploration of the genetic and epigenetic integrity of the resultant embryos as well as the health of offspring in future studies. In conclusion, the detrimental impacts elicited by environmental factors such as electromagnetic radiation and heat on the male reproductive tract, has identified that generating a state of oxidative stress is a key susceptibility of this biological system.
- Subject
- sperm function; environmental stress; heat stress; mobile phone radiation; radiofrequency electromagnetic radiation; fertility; spermatozoa; testis; DNA damage; oxidative stress
- Identifier
- http://hdl.handle.net/1959.13/1387487
- Identifier
- uon:32615
- Rights
- Copyright 2018 Brendan Houston
- Language
- eng
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