Reproduction Abstracts

Introduction: Aflatoxins are poisonous by-products from soil-borne fungus Aspergillus flavus, which involved in the decomposition of plant materials. Various food products, such as maize, sorghum, millet, rice and wheat, are contaminated with aflatoxins. Aflatoxin B1 (AFB1) is the most toxic aflatoxin and classified as carcinogen and mutagen. The lethality and toxicity extent of AFB1 varies between animals and organs. In the current study we examined the effects on sperm function.

Methods: Sperm isolated from fresh ejaculates or epididymis compartments (head, body or tail) were capacitated in vitro for 4 h with 0, 0.1, 1, 10 and 100 μM AFB1. The integrity and functionality of sperm were examined simultaneously by florescent staining at 0, 2 and 4 h of incubation. Following capacitation, acrosome reaction (AR) was induced by Ca²⁺ ionophore and examined by FITC-PSA.

Results and discussion: Sperm plasma viability, expressed by membranes integrity, was reduced in sperm isolated from ejaculate, epididymis (head or tail) and treated with AFB1 (1, 10 or 100 μM P<0.006). Similar reduction was observed when sperm isolated from the epididymis body exposed to 10 μM (P<0.05). In sperm isolated from the epididymis tail, AFB1 reduced the proportion of sperm with Ca²⁺-activated AR (100 μM 4 h P<0.05), but had no effect on pseudo-AR. On the other hand, AFB1 did not affect induced- or pseudo-AR in sperm isolated from the ejaculate. AFB1 impaired mitochondrial membrane potential (ΔΨm) in sperm isolated from ejaculate (10 μM 4 h P<0.02) or from epididymis tail (1 μM 2 h P<0.05).

The findings expose the harmful effects of AFB1 on sperm viability, acrosome integrity and ΔΨm. We postulate that AFB1-induced impairment in these characteristics might further affect sperm fertility competence.