Subchronic oral administration of gossypol-acetic acid (GAA) alters the distribution and utilization of radioiron in male rats.

Gossypol-acetic acid (GAA) has been shown to be a powerful chelator of iron. To determine how subchronic administration of GAA affects the distribution and utilization of radioiron, male Holtzman rats, which had received a daily oral dose of GAA (20 mg/kg body weight) for 16 weeks, were injected i.p. with [59Fe]citrate (activity = 16.5 muCi/kg body weight) and [59Fe] incorporation into circulating erythrocytes, bone marrow, liver, spleen, skeletal muscle, and urine was measured 6, 12, or 24 h after [59Fe] administration. Iron [59Fe] incorporation was enhanced in the spleens, livers, bone marrow, and blood of the GAA-treated rats, and increased as the time post-[59Fe] injection increased. Hematological parameters remained within normal limits throughout the 16-week treatment period, suggesting an erythropoietic compensation in the GAA-treated rats. Iron status was markedly different in the GAA-treated rats at the end of the 16 week treatment period, suggesting altered iron utilization. The data suggest that [59Fe] is preferentially distributed to the erythroid tissues of GAA-treated rats for utilization in erythropoiesis.

Radioiron utilization and gossypol acetic acid in male rats.

The 24-h incorporation of 59Fe into circulating red blood cells, bone marrow, urine, liver, spleen, and skeletal muscle was measured in splenectomized and sham-splenectomized rats which had received a daily, oral dose of gossypol acetic acid (20 mg GAA/kg body wt) for 91 days. A significant decrease in total body weight gain was observed in all GAA treated animals. Splenectomized rats dosed with GAA exhibited a significant decrease in hemoglobin concentration, hematocrit and erythrocyte count. A significant increase in 59Fe incorporation by red blood cells and a decrease in hepatic incorporation of 59Fe indicate a preferential utilization of iron in erythropoiesis among GAA treated animals.

The effect of gossypol acetic acid on female reproduction.

The effects of gossypol acetic acid (GAA) on various aspects of female rat reproduction were evaluated. Forty sexually mature, nulliparous female Holtzman rats received a daily, oral dose of GAA (20 mg GAA/Kg body wt) for 60 days. Nineteen control animals were utilized. Throughout the treatment period, GAA treated rats had significantly more irregular estrous cycles than did controls, and the mean duration of an estrous cycle in the GAA rats was significantly longer than that of controls. A significantly lower body weight gain was observed in all GAA treated animals. A prolonged time for mating, a decrease in incidence of pregnancy, and a reduction in number of viable embryos at Day 13 of gestation were noted among GAA treated animals. Weaning weights of offspring from GAA dams were significantly less than weaning weights of offspring from control dams.

Deposition pattern of the antifertility agent, gossypol, in selected organs of male rats.

Male rats received daily, oral doses of gossypol-acetate (40 mg/kg body wt) for 2, 4, or 8 weeks to determine patterns of gossypol deposition in the spleen, liver, heart, kidneys, lungs, and testes during establishment of a gossypol-induced infertility. Infertility was exhibited at the end of the 4-week dosing period. Free and bound gossypol accumulated in all of the organs.

Scanning electron microscopic study of spermatozoa from gossypol-treated rats.

Spermatozoa from the cauda epididymidis of gossypol-treated rats exhibit distinctive departures from the morphology of spermatozoa from control rats: wrinkled and disorganized cell membrane in the head and tail regions, cell membrane missing from segments of the tail midpiece and principal piece regions, malformed heads, decapitate spermatozoa, retention of a cytoplasmic droplet at variable loci along tail midpieces, and looped tails. The observations suggest that gossypol exerts its contraceptive effect during spermatocytogenesis and spermiogenesis, including the posttesticular development and maturation of spermatozoa in the epididymis.

Effect of gossypol on the ultrastructure of rat spermatozoa.

Gossypol was found to induce sterility in male rats when administered orally. A reduction in the number of spermatozoa in the epididymis from the gossypol-treated rats was observed when compared to the control animals. An examination of the spermatozoa from the treated rats showed the following ultrastructural modifications: disorganization of the mitochondiral sheath and missing cell membrane from the middle piece, broken cell membrane and missing members of both outer fibers and inner microtubules of the principal piece, and broken cell membrane of the sperm head. Serial mating experiments proved that gossypol-treated males were indeed sterile. The results suggest that gossypol at low concentrations is able to affect the motility of spermatozoa, thus contributing to its contraceptive action.

The accumulation pattern of ingested gossypol in selected organs of the rat.

Bound gossypol levels in the spleen and kidney of rats ingesting dietary gossypol (0.98%) varied directly with the feeding intervals of 6, 14, 28 and 35 days. Free gossypol level in the kidney, spleen and lungs increased for 14 days and then tended to decrease as the feeding period was extended.