D. Shemi

Suppression and Recovery of Spermatogenesis in Dibromochloropropane Treated Rats

Unterdrückung und Erholung der Spermatogenese bei Dibromchloropropanbehandelten Ratten

Long Term Effects of Dibromochloropropane (DBCP) on Male Rats' Reproductive System

Summary: Adult male rats were injected s.c. once a week for 3 weeks with DBCP, 20 mg/kg B.W. Animals were sacrificed 5, 9, 13, 17, 25 and 50 weeks after last injection. Body weight was recorded once a week. Prior to sacrifice each male was presented with proestral females in order to determine the males mating behaviour and fertility. Testes were removed, weighed and taken for standard histological examination. DBCP treatment caused a reduction of body weight which reverted back to control levels some 17 weeks post injection. Testes weights were reduced and remained low despite the recovery of body weight. Generally, all males showed normal mating behaviour but most of them were infertile. Testicular histology showed a correlation between decreasing testicular weight and increasing percentage of degenerated seminiferous tubules, which was on the other hand correlated with decreasing tubular diameter. Serum levels of FSH and LH were significantly increased in the infertile DBCP treated males while values for the fertile ones were similar to those of controls. There were no differences in serum testosterone levels between DBCP treated and control animals. It is concluded that in DBCP treated rats testicular degenerative damages are associated with increased circulating gonadotrophin levels and with normal testosterone levels. Although mating behaviour is unaffected fertility is depressed and does not recover for at least 50 weeks post injection. It is suggested that DBCP treatment affects mainly the activity of the Sertoli cells while the Leydig cells are affected to a much lesser degree.

The Effect of Dibromochloropropane (DBCP) on In Vitro Cyclic AMP Levels and Testosterone Production in Rat Testes

Adult male rats were injected s.c. once a week for 3 weeks with DBCP, 20 mg/kg BW. Animals were sacrified 20 weeks after last injection. Body and testes weights were recorded and testes were taken for standard histological preparation and for in vitro experiments. The in vitro experiments were carried out on testes slices (90–110 mg) incubated for 3 h with or without the addition of hCG to the incubation medium. Cyclic AMP content of the tissue as well as testosterone released into the incubation medium were determined. Testes weights of DBCP treated animals were 68 % lower that that of controls. AU semiferous tubules were damaged and shrunken, thus, their number per microscope field was 2.6 times that of controls. Cyclic AMP levels in testes slices were similar in both DBCP treated and controls. The addition of hCG stimulated cyclic AMP accumulation to a much higher level in the DBCP treated than in controls. When calculated per one pair of testes the content in unstimulated pair was more than twice that of DBCP treated. Stimulation of hCG increased both DBCP treated and controls to similar levels. Testosterone release into the medium by slices was higher in DBCP treated than in controls and so was also the increment due to hCG stimulation. Similar results were obtained when testosterone release was calculated per one pair of testes.

The effect of high and low ambient temperatures on PGE2 and TNF-α production by rat glial brain cultures

This study was undertaken to investigate the effect of changes in incubation temperature on PGE 2 and TNF-α production by rat glial brain cultures after LPS stimulation. One-hour incubation at temperatures of 4°C, 37°C, 39°C and 42°C were used. Treatment of cultures with 10 μg/ml LPS from Escherichia coli caused a significant elevation of PGE2 production 24 h after incubation at control temperatures of 37°C and the experimental temperatures of 4°C, 39°C and 42°C. While high ambient temperatures of 39°C and 42°C reduced LPS-stimulated production, compared to exposure to 37°C, exposure to 4°C did not do so. On the other hand, exposure of the cultures to a temperature of 39°C and 42°C for 1 h did not alter LPS-stimulated TNF-α production, while exposure to a temperature of 4°C significantly reduced this elevation.

Gonadotoxicity and kinetics of dibromochloropropane in male rats

Adult male rats were injected with [3H]dibromochloropropane dissolved in dimethylsulfoxide containing about 10 X 10(6) dpm. Blood from the tail and 24-h urine samples were collected up to 2 days post-injection. Tissue samples were further taken from the kidneys, liver, spleen, adrenals, epididymis, seminal vesicles and testes 7 h and 7 days post-injection. The results demonstrate that there is no preference in labelling of the testes compared with other organs, and the kidney and liver may have an important role in the elimination of DBCP.