Lack of effects of recombinant human GH on spermatogenesis in the adult cynomolgus monkey (Macaca fascicularis).

OBJECTIVE: The effects on male reproductive parameters after 1 year of treatment with recombinant human GH to the cynomolgus monkey were investigated. DESIGN: Twenty-four male cynomolgus monkeys were given daily subcutaneous doses of 0 (vehicle) (n=7), 0.4 (n=5), 2.0 (n=5) and 10.0 (n=7) IU/kg bodyweight for 52 weeks. At completion of the treatment period two control and two high-dose animals were left for a 12-week treatment-free period. METHODS: Before and during the treatment period and during the recovery period, sperm analyses, testicular volume measurements and hormone analyses of prolactin (PRL), LH, FSH, testosterone and IGF-I in serum, and analysis of serum antibodies against human GH were performed. Testicular morphology was monitored by biopsies, predose and on day 15 of the study, and with light microscopy on organ samples collected at time of death, at the end of the treatment, and during recovery periods respectively. RESULTS: Of all studied parameters, alterations were observed only in serum levels of IGF-I and PRL. IGF-I showed a dose-dependent increase throughout the treatment, with a normalisation during the treatment-free period. PRL decreased significantly in animals given 10.0IU/kg per day from week 14 of treatment and throughout the study but with a normalisation upon cessation of treatment. Spermatogenesis, as judged from semen analysis, testicular volume measurements and testicular morphology was not affected. CONCLUSION: This controlled preclinical study demonstrates that high doses of human GH do not alter male reproductive parameters in a non-human primate model.

Effects of constant infusion with insulin-like growth factor-I (IGF-I) to immature female rats on body weight gain, tissue growth and sexual function. Evidence that such treatment does not affect sexual maturation of fertility.

Plasma levels for insulin-like growth factor-I (IGF-I) steadily increase in female rats between 20 and 40 d of life, and this increase is intimately related to the wellknown growth spurt occurring at this age. Since specific actions of IGF-I related to sexual function have been described at the ovarian and hypothalamic levels, an endocrine role of rising circulating IGF-I levels during sexual maturation cannot be excluded. Therefore, the impact of adult-type plasma IGF-I levels during the juvenile age, on body weight (BW) gain, growth of several organs, sexual development, and fertility has been evaluated. Female Sprague-Dawley rats were infused with rhIGF-I (2 and 4 micrograms/g BW/d, using Alzet minipumps), between 20 and 41 d of life. When infusing 2 micrograms/g BW/d, plasma levels for IGF-I were increased 1.5- to 2-fold over controls at all ages studied. They were further increased with the higher dosage, but only after 35 d of age. Plasma levels for insulin-like growth factor binding protein (IGFBP)-1 to -3 were clearly increased. BW gain was significantly increased, but only with the higher dosage. Tail length was never modified. In contrast, a growth acceleration for spleen, kidneys, adrenals, and ovaries was observed with both dosages. The ovarian weight of treated animals represented approx 140% of control animals with the 4 micrograms/g BW/d dosage. Histology of the enlarged ovaries did not reveal any abnormalities. No meaningful modification of the timing of vaginal opening was observed, and fertility was not comprised by previous rhIGF-I infusion during 20-41 d age period. In summary, early exposure to increased (adult-like) plasma IGF-I levels did not modify BW gain or tail length, but affected the development of spleen, kidneys, adrenals, and ovaries. Exposure to supraphysiological plasma IGF-I levels (> 1200 ng/mL), accelerated BW gain and increased the weight of all organs studied. No signs of precocious sexual maturation were seen and fertility was normal. In conclusion, prematurely increased plasma IGF-I levels affected somatotropic parameters, but not the onset of sexual function.

Effects of constant infusion with insulin-like growth factor-I (IGF-I) to immature female rats on body weight gain, tissue growth, and sexual function : Evidence that such treatment does not affect sexual maturation or fertility.

Plasma levels for insulin-like growth factor-I (IGF-I) steadily increase in female rats between 20 and 40 d of life, and this increase is intimately related to the wellknown growth spurt occurring at this age. Since specific actions of IGF-I related to sexual function have been described at the ovarian and hypothalamic levels, an endocrine role of rising circulating IGF-I levels during sexual maturation cannot be excluded. Therefore, the impact of adult-type plasma IGF-I levels during the juvenile age, on body weight (BW) gain, growth of several organs, sexual development, and fertility has been evaluated. Female Sprague-Dawley rats were infused with rhIGF-I (2 and 4 µg/g BW/d, using Alzet minipumps), between 20 and 41 d of life. When infusing 2 µg/g BW/d, plasma levels for IGF-I were increased 1.5- to 2-fold over controls at all ages studied. They were further increased with the higher dosage, but only after 35 d of age. Plasma levels for insulin-like growth factor binding protein (IGFBP)-1 to-3 were clearly increased. BW gain was significantly increased, but only with the higher dosage. Tail length was never modified. In contrast, a growth acceleration for spleen, kidneys, adrenals, and ovaries was observed with both dosages. The ovarian weight of treated animals represented approx 140% of control animals with the 4 µg/g BW/d dosage. Histology of the enlarged ovaries did not reveal any abnormalities. No meaningful modification of the timing of vaginal opening was observed, and fertility was not compromised by previous rhIGF-I infusion during the 20-41 d age period. In summary, early exposure to increased (adult-like) plasma IGF-I levels did not modify BW gain or tail length, but affected the development of spleen, kidneys, adrenals, and ovaries. Exposure to supraphysiological plasma IGF-I levels (>1200 ng/mL), accelerated BW gain and increased the weight of all organs studied. No signs of precocious sexual maturation were seen and fertility was normal. In conclusion, prematurely increased plasma IGF-I levels affected somatotropic parameters, but not the onset of sexual function.

Inhibition of smooth muscle cell proliferation and neointimal growth by low-anticoagulant heparin.

Low-anticoagulant heparin (LA-heparin) obtained by affinity chromatography on antithrombin III Sepharose inhibits the proliferation of cultured arterial smooth muscle cells in an in vitro bioassay system as effectively as standard heparin. A growth inhibition of smooth muscle cells of about 60% is achieved when LA-heparin or heparin is added to the culture medium to a concentration of 50 micrograms/ml. In normolipemic rats LA-heparin suppresses the formation of neointimal thickenings and stenosis after balloon catheter-induced deendothelialization of the carotid artery. In terms of mass a dose of 5 mg/kg body weight/d given subcutaneously twice daily one week before and 2 weeks after balloon injury the cross sectional area of the neointima is reduced to 36% as compared with the nontreated control group (100%). This 64% reduction is statistically highly significant (p < 0.001). After treatment with 0.5 mg LA-heparin/kg/d the reduction of the neointima was 11% (p < 0.05). At a dose of 5 mg/kg body weight single or repeated administrations of LA-heparin caused only a small and transient increase in activated partial thromboplastin time values. The results show that subcutaneous administration of LA-heparin very effectively prevents smooth muscle cell proliferation and balloon catheter-induced neointimal growth. The well tolerated systemic application of this chemically non-modified LA-heparin might justify clinical trials for prevention of restenosis after percutaneous transluminal coronary angioplasty or other invasive cardiovascular interventions without complications of bleeding.

Growth hormone administration after treatment in the resistant hepatocyte model does not affect progression of rat liver carcinogenesis.

Male and female Wistar rats were treated according to a slightly modified resistant hepatocyte model, i.e. initiation with diethylnitrosamine and selection of initiated cells with 2-acetylaminofluorene and partial hepatectomy. Two weeks after selection, rats of each sex received daily subcutaneous injections of either recombinant human growth hormone (2.5 IU/kg) or saline for 6 weeks. No effects on growth of early enzyme-altered liver lesions were recorded. The long-term part of the experiment did not show any differences due to growth hormone treatment in terms of incidence or latency time for development of either malignant liver tumors or kidney tumors. Male rats developed liver tumors more frequently than the female rats whereas a higher incidence of kidney tumors was observed in the female rats. Several different malignancies at other sites were also recorded, with no differences between the groups with or without growth hormone treatment. In conclusion, no modifying effects of human growth hormone administration during the post selection phase of the resistant hepatocyte model could be demonstrated on either tumor promotion or tumor progression.

Turnover of tissue plasminogen activator in normal and hepatectomized rabbits.

The distribution, and clearance of the tissue plasminogen activator (tPA) was studied in rabbits, rats and mice. Following an intravenous injection of I-labelled tPA a large portion of the radioactive dose was rapidly accumulated in the liver. After one hour the radioactivity in the liver was less than 5 per cent of the injected dose. The highest activity was then found in the intestine, stomach and in the blood. Gel filtration of plasma taken one hour after the injection revealed that the major part (60%) of the radioactivity was present as low molecular weight metabolites or free iodine. The remaining activity was present as high molecular weight inhibitor complexes (26%) or as free tPA (15%). In order to study in vivo reactions between tPA and plasma inhibitors without hepatic interference, plasma turnover was also studied in hepatectomized rabbits. High amounts of radioactivity remained in the plasma after one hour. Gel filtration of this plasma revealed that 54 per cent of the radioactivity was bound to inhibitors, 34 per cent circulated as free tPA while a minor portion (12%) was found as free iodine or metabolites. The half-life of fibrinolytically active tPA in hepatectomized rabbits was 40 minutes compared to 2 minutes in intact rabbits. The increase in the half-life of tPA in hepatectomized rabbits also resulted in an improved thrombolytic effect after treatment with 0.5 mg tPA.

Testicular lesions of coprine and benzcoprine.

The effect on the testis of the disulfiram-like compounds benzcoprine (N-[1-ethoxycyclopropyl] benzamide) and coprine (N5-[1-hydroxycyclopropyl]-L-glutamine) was studied in rats and dogs. Severe degeneration of the seminiferous epithelium was induced in rats by subacute oral administration of each compound. 60 days after termination of treatment with benzcoprine most seminiferous tubules contained only occasional spermatogonia and the testicular weight was markedly decreased. The blood-testis barrier was unaffected in the benzcoprine-treated rats as judged by a lanthanum tracer technique. In dogs, oral administration of benzcoprine for 1 month caused impaired spermatogenesis, degeneration of germ cells and a decrease in the testicular weight. The results indicate that both compounds act directly on the germ cells. The effect is similar to that of alkylating compounds. Other effects of benzcoprine and coprine (bone marrow depression, lymphocytopenia, positive Ames test in organisms sensitive to base-pair substitution) are well-known properties of alkylating agents. In conclusion benzcoprine and coprine were found to cause severe changes in the testis in rats and dogs, probably due to a direct effect on the germ cells.