Goat spermatozoa were incubated in vitro in Tris-citrate buffer, pH 7.2, containing 0, 40, 80, or 160 mug of Naja haje venom/mL buffer for 4 hours. During incubation, the percentages of sperm motility were decreased, while percentages of dead spermatozoa were increased in a time and concentration-dependent manner. The effect of venom concentrations on the ultrastructure of incubated spermatozoa was examined hourly by scanning (SEM) and transmission (TEM) electron microscopy. SEM results showed plasma membrane wrinkling at heads of some spermatozoa after 2 h incubation with 40mug venom. Most spermatozoa suffered membrane wrinkling after 4 h incubation. However, incubation with 80 mug venom caused membrane fractures in most sperm heads after 1 h incubation. The extent and depth of these fractures were increased after 2-3 h incubation. After 4 h incubation, plasma membrane focal erosion of many spermatozoa heads was common. Incubation with 160 mg venom induced sperm head swollen plasma membranes after 1 h incubation. Ruptured and disintegrated membranes were seen after 2 h; lysis and removal of external surface of spermatozoa head plasma membranes were recorded after 3-4 h incubation. TEM indicated slightly swollen areas on the sperm head plasma membrane, but showed normal nuclei, acrosomes, and tail regions after 2 h incubation in 40 mug cobra venom. The swollen areas were accompanied by sperm head membrane disintegration as well as membrane irregularities and distortion of tail mitochondrial cristae after 3-4 h incubation. However, incubation with 80 mug venom showed focal areas of membrane lysis and discontinuity in the sperm heads and tails increasing with incubation time. Severe axoneme and tail longitudinal fiber degeneration and increased numbers of distorted mitochondrial cristae were also observed after 3-4 h incubation. Spermatozoa incubation with 160 mug venom increased severity of plasma membrane dissolution, disintegration, and rupture. Axoneme disorganization and tail longitudinal fiber fusion were seen after 1-2 h; complete deformation of the motility system was recorded after 3-4 h incubation. Nuclei were normal, but acrosomes were partially damaged, and distorted mitochondrial cristae were increased after 4 h incubation. The results indicated that cobra venom induced a concentration and time-dependent alterations on spermatozoa plasma membrane as well as obvious deformation on the motility system and tail mitochondria, which are responsible for sperm viability and fertilizing ability.

The effect of intramuscular (IM) injection of a sub-lethal dose of Naja haje cobra venom (0.015 mug/gm body weight) on the ultrastructure of renal cortical tissues of rabbits was studied at different time intervals after envenomation. Succinic dehydrogenase (SDH) enzyme activity was also detected in the renal cortical tubules. Three hours after venom injection, slight changes were seen in visceral cells and glomerular endothelia. The cortical tubular epithelia revealed an increase of lysosomal structures, cytoplasmic vacuolization, and nuclear irregularity. Severe ultrastructural changes were recorded 6 hours after envenomation, including hypertrophied parietal cells, blebbed visceral epithelial cells, and foot process disorganization. Dilated glomerular capillaries lined by hypertrophied endothelial cells and signs of mesangiolysis were also observed. The proximal tubular epithelia showed vesiculated endoplasmic reticulum and numerous lysosomal vacuoles, while the distal tubular epithelia were mostly necrotic. These alterations were more intense 12 hours after venom injection. Parietal and visceral cells showed similar changes to those of the six-hour group. Most of the glomerular endothelial cells lost their integrity and diffused into the capillary lumen. Mesangiolysis was also observed. The proximal tubular epithelial cells revealed severely affected cellular organelles, dilated brush borders, disruption of the basal membrane infoldings, and cellular necrosis. The distal tubular epithelia lost most of their cytoplasmic electron density and cellular organelles. Necrotic cells were also seen. Generalized mitochondrial alterations were observed in all renal cortical cell types accompanied by a marked depletion of SDH enzymatic activity in those cells. It is believed that these venom-induced non-specific lesions could be due to secondary synergistic action of more than one venom toxin, which mainly target the mitochondria in all components of renal cortical tissues. This could lead to an ischemic condition that could be responsible for the appearance of these ultrastrucural alterations.