Conversion of apoptosis to necrosis and the corresponding alteration in the oxidative milieu of male germ cells of rat under acute heat stress: An experimental study

Increased scrotal temperature can disrupt spermatogenesis leading to male infertility. Germ cells being heat sensitive maintain their genetic integrity via protective mechanism originated from the cell itself or by means of cell death. However, qualitative differentiation of how reactive oxygen species and antioxidant enzymes regulate signaling pathways of cellular damage including DNA fragmentation at varied temperatures remains unexplored.

The study was designed to evaluate the effects of heat mediated oxidative stress on male germ cells. Also, the time-dependent qualitative variation in the germ cell death was studied.

Thirty male Wistar rats were randomly segregated into five major groups (n=6/each) i.e., Control, 30, 45, 60, and 90-min counterparts according to heat treatment protocol. Quantitation of DNA and DNA ladder studies was performed along with various biochemical parameter like lipid peroxidation (LPO), glutathione, catalase, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutatione reductase (GR), glutathione-s-transferase (GST).

Animals receiving heat treatment for 30-min and 45-min revealed systematic and gradual response to heat stress; whereas, 60-min and 90-min treated animals showed a typical and abrupt change of the internal milieu of germ cells. Laddering and smearing effect of damaged DNA in 30 and 45 min and 60 and 90 min heat treated animals was seen respectively.

As the duration of heat treatment increases, the rate of apoptosis reaches an optimum level, and a further increase in the duration of heat treatment converted the mode of cell death from apoptosis to necrosis, implicitly due to severe oxidative attack