To study the effect of an acute exposure to a sinusoidal extremely low frequency magnetic field (50 Hz, 1mT) on the ability of boar mature spermatozoa to acquire the fertilization competence in vitro.
Semen samples were collected from three boars.
Exposure duration: continuous for 1 h, 2 h or 4 h
|magnetic flux density||1 mT||-||measured||-||-|
The extremely low frequency magnetic field exposure did not affect sperm viability and morphology during the first hour of exposure when sperm calcium homeostasis was already affected. Exposed spermatozoa showed significantly lower resting intracellular calcium levels than those of controls. This result was dependent on a lower extracellular calcium intake (as demonstrated by the lower uptake of calcium-45). Moreover, exposed spermatozoa displayed a parallel decrease in intracellular calcium store as confirmed by lower calcium release (triggered by the addition of thapsigargin) and by the progressive reduction in mitochondrial activity. As a consequence, after one hour of exposure cells displayed a reduced sperm motility, a modest reactivity when co-incubated with solubilized zona pellucida and a decrease in oocyte penetrating ability. Additionally, after 2 h or 4 h of exposure signs of morphological damage appeared on plasma membrane and at acrosomal level.
In conclusion, an extremely low frequency magnetic field negatively influences spermatozoa first by impairing cell calcium homeostasis and then by dramatically affecting sperm morphology and function.