Electron microscopic observations of the effects of gossypol on the human endometrium

Effects of diets containing free gossypol on follicular development, embryo recovery and corpus luteum function in Brangus heifers treated with bFSH

Thirty 2 yr old Brangus heifers were randomly assigned to 1 of 3 dietary treatments: Control, 0 g of free gossypol (FG) per head per day (FGHD) from corn and soybean meal (SBM); 5 g of FGHD from cottonseed meal (CSM); and 15 g of FGHD from whole cottonseed (WCS). Blood samples were collected weekly for serum progesterone (P(4)) and later quantified by RIA. Whole blood was collected on Days 1, 28, 42, 56 and 70 for erythrocyte fragility (EF) analysis. Following 65 d on dietary treatments and estrus detection, the heifers received bovine-FSH (bFSH) once daily on Days 10, 11 and 12 postestrus, and PGF(2alpha) on Day 12 postestrus. Fifteen of the thirty heifers were randomly selected, and 12 h following PGF(2alpha), the ovaries were removed and follicular diameters, ovarian weight and stromal weights were recorded. Follicular fluid was analyzed for steroid content by RIA. The remaining fifteen heifers were artificially inseminated. Embryos were recovered non-surgically on Day 7 postestrus and graded, and the recovery efficiencies were calculated. Following embryo collection, both ovaries were removed, the number of CLs was recorded, and CL P(4) content was determined by RIA. By Day 42 of treatment, heifers receiving CSM had elevated (P < 0.04) EF compared with the Controls, and remained elevated above that of Controls throughout the study. At Day 70, the CSM heifers tended to have higher (P < 0.07) EF than the WCS group, which in turn tended to be higher (P < 0.06) than the Controls. The Control and CSM heifers gained weight during the 70 d treatment period, while heifers consuming WCS lost weight (P < 0.05). Ovarian and stromal weights did not differ (P > 0.10) among treatment groups. Heifers receiving CSM had fewer (P < 0.05) follicles > 5 mm than WCS or Control heifers. Follicular fluid weights and steroid content did not differ (P > 0.10) among treatments. Both CL weight and the number of CLs per heifer were similar (P > 0.10) among treatments. Heifers receiving CSM or WCS had a higher (P < 0.003) CL P(4) content per gram of CL tissue than the Controls. Progesterone content per CL was greater in WCS heifers (P < 0.003) than in CSM heifers, while both the CSM and WCS heifers had a higher CL P(4) content than the Control heifers. Weekly and Day 7 postestrus serum concentrations of P(4) were similar (P > 0.10) among treatments. The number of embryos recovered, number of degenerated embryos, embryo grades and recovery efficiencies were not affected (P > 0.10) by dietary treatments. To standardize heifers relative to the number of degenerated embryos, the percentage of degenerated embryos recovered was calculated and tended to be greater (P < 0.06) in heifers consuming CSM than in either the Control or WCS groups. While most ovarian, follicular and embryo characteristics were not affected by dietary free gossypol, these results suggest that differences in the availability of free gossypol and/or dietary components between CSM and WCS may influence weight gain, CL P(4) content and embryo viability.

Presence of antitumor activities in the milk collected from gossypol-treated dairy cows

Two human breast carcinoma cell lines (MCF-7, MCF-7 Adr) and a rat esophageal cancer cell line (RE-B2T) were used to evaluate the antiproliferative potential of gossypol (GP)-containing milk (GP-Milk), which was collected from Brown Swiss dairy cows treated daily with federally allowable 450 ppm of GP for 6 days. Treatment of the cultured cancer cells with GP-Milk for 24 h significantly inhibited the rates of 3H-thymidine incorporation during the ensuing 3-h period in all three tumorigenic cell lines. The inhibitory effects of GP-Milk occurred in a dose-dependent manner in all cases, but the calculated ED50 varied with cell lines. ED50 for GP-Milk was estimated at 10% for wild-type MCF-7 human breast cancer cells, 15% for multidrug-resistant MCF-7 Adr human breast cancer cells and 50% for RE-B2T rat esophageal carcinoma cells. The potential of GP-Milk as a dietary supplement for the prevention and/or treatment of human breast cancer is discussed in this paper.

Genotoxic effects of gossypol acetate on the ovary of Rhinopoma kinneari wroughton (Microchiroptera: Mammalia)

Female Rhinopoma kinneari, a microchiropteran bat (body weight Ca 15.0 gm to 20.0 gm), was used as a model to evaluate the effect of a single oral dose of 10 mg of gossypol acetate on the ovarian histology at day 2, 4, 6 and 8, respectively. Maximal damage to these organs was seen on day 2. The test drug induced widespread disturbance in the ovarian histoarchitecture as evidenced by an extensive degeneration of follicle types. Degenerative changes were marked by pycnosis, chromatolysis of nuclei, desquamation of granulosa cells and their subsequent dissolution. Intensity of protein staining was increased with time, indicating marked damage to ovarian constituents. It is suggested that gossypol may cause antifolliculogenic activity.

Gossypol pharmacokinetics in mid-lactation Brown Swiss dairy cows

A bolus equivalent to 450 ppm (dosage based on average feed intake for lactating dairy cows of similar mass) of gossypol was administered orally to three Brown Swiss dairy cows in mid lactation daily for a 7-day treatment period. Blood samples were taken during a 2-day pretreatment period, the 7-day treatment period and a 6-day recovery period. The serum recovered from the cows was stored at -20 degrees C until analysis for extractable gossypol content. The highest concentration of gossypol (a mean of 0.53 microgram/ml serum) was attained in all the cows on day 6 of the treatment period, indicating that a steady-state condition had been reached before the end of the treatment period. The gossypol concentrations then gradually declined during the 6-day recovery period but never fell to the zero baseline. The cows exhibited terminal elimination half-lives of 67, 67.5 and 40 h. Gossypol elimination was best described by a bi-exponential decay curve in two cows and a mono-exponential decay curve in the remaining cow.

An ultrastructural study of the effects of gossypol on the endometrium of the female rat

Abnormal desmosomes were found in the endometrial epithelial cells of rats treated orally with gossypol acetic acid at a dose of 60 mg/kg/day for 30 days. Desmosomes in the endometrium of rats treated at 40 mg/kg/day were similar to those of controls. Abnormalities included an increase in desmosome number with prominent filamentous interconnections, asymmetry, disorganization of tonofilaments, missing tonofilaments, missing desmosomal plaques that did not appear to line up with those of the adjacent cell. It is thought that the antifertility actions of gossypol may be due to a disturbance of desmosome formation. This would cause a disruption of endometrial cell adhesion as well as an alteration in the microenvironment within cytoplasmic domains. These changes could lead to an endometrial environment unfavorable to fetal development.

Gossypol effects on cultured normal and malignant melanocytes

Gossypol, a polyphenolic compound known to interfere with spermatogenesis, was found to have differential cytotoxic effects on normal and malignant melanocytes in culture. Ultrastructurally it caused marked swelling and vacuolization of mitochondria; there was an almost complete loss of cristae but the outer mitochondrial membrane was retained. The cytotoxicity seemed to be selective for actively proliferating cells, regardless of normal or malignant origin. An endothelial cell line (RF/6A) derived from the choroid-retina of the eye of a rhesus fetus was extremely sensitive to its toxic effect. The mechanism of action is still unknown. The fact that mitochondria are predominantly damaged suggests that toxicity involves a perturbation of energy metabolism and the membrane transport system.