The present study was conducted to examine the presence of insulin-like growth factor- receptor (IGF-1R) in human sperm cell. The IGF-1R monoclonal antibody (MAb) specifically immunoprecipitated two protein bands of approximately 135 and approximately 220 kD, respectively, from the reduced human sperm extract. These bands correspond to the alpha-subunit and partially reduced IGF-1R molecule, respectively. The immunocytochemistry experiments indicated the presence of IGF-1R primarily in the equatorial regions, along with a weak binding in the acrosomal regions of human spermatozoa. These data indicate that the IGF-1 receptor is present in the human sperm cell. Since the IGF-1 receptor has tyrosine kinase activity and its ligand IGF-1 is present in the seminal plasma, the IGF-1 system (IGF-1R/IGF-1/IGF-binding protein) may be involved in the signal transduction pathway leading to sperm capacitation and acrosome exocytosis.

The effects of an aqueous extract of Carica papaya seeds (20 mg/kg body weight/animal/day orally and 5 mg/kg body weight/animal/day i.m. for 60 days) were investigated for contraceptive efficacy and other related side effects in male albino mice, Mus musculus. The data revealed that the extract might be causing an androgen deprived effect to target organs resulting in alterations in the internal milieu of the cauda epididymis especially. The treatment did not, however, affect the testicular sperm count suggesting that it acted at the post-testicular level which lead to a reduction of cauda epididymal sperm motility and thus the treatment brought about a significant reduction in fertility rate. The induced effects were transient and reversible upon withdrawal of the treatment, elucidating that functional sterility could be induced by the aqueous papaya seed extract in rodents.

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