Some anti-cancer drugs, such as procarbazine (PCZ), are associated with irreversible damage to spermatogenic function and cause sterility in men. In the present study, protection of spermatogenesis by gonadal steroid hormones during PCZ treatment was investigated in male rats. LBNF1 hybrid rats were chosen for these studies because the response of the testis to PCZ was more uniform than in a stock of Sprague-Dawley outbred rats. Mature male LBNF1 rats were subcutaneously implanted with cholesterol (C)-, testosterone (T)-, and/or estradiol-17 beta (E)-containing capsules, and 5-10 weeks later given one or four weekly intraperitoneal injections of PCZ at a dose of 200-250 mg/kg of body weight. Hormone capsules were removed 24 hours after the last PCZ injection and the animals were killed 10-12 weeks later. Testicular weights, sonication-resistant sperm head counts, and quantitative testicular histology revealed protection of the spermatogenic epithelium from PCZ toxicity by gonadal steroid hormones when compared with the C controls. Protection was observed against both single and multiple injections of PCZ. A combination of T and E capsules provided better protection than T alone. This model system is suitable for studies of the mechanism of protection of spermatogenesis from chemotherapy-induced damage.

Protection by Gonadal Steroid Hormones Against Procarbazine-Induced Damage to Spermatogenic Function in LBNF1 Hybrid Rats

This review focusses on the mechanisms of testicular toxicity, and the underlying requirement for a detailed understanding of the characteristics of the testis. Factors such as active mitosis, the presence of a blood-testis barrier, the spermatogenic cycle, and hormonal control, complicate the situation with regard to toxicity. However, the general mechanisms of testicular toxicity types can be classified as follows: 1) Direct-action against spermatogenic epithelia; 2) Hormonal indirect effects on spermatogenesis; 3) Direct or indirect mechanisms affecting sperms; 4) Circulatory disturbances affecting the testis; 5) Other miscellaneous actions. In the histological evaluation of testicular toxicity, histological patterns of toxic lesions induced by different model chemicals, categorized on the basis of their mechanisms of action, are very helpful. For typical examples are cyclophosphamide, nitrobenzene, ethane-1, 2-dimethanesulfonate, and cadmium chloride. Studies with these compounds have strongly suggested that early changes, rather than those occurring at late stages, are of particular assistance for understanding their mechanisms of action.

Mechanisms of testicular toxicity

Summary: We treated 20 young men, after giving informed consent, with buserelin during their tumor treatment period. 11 of them suffered from Hodgkins disease, 2 had a non-Hodgkin lymphoma, 6 had a seminoma and 1 patient had an embryonic carcinoma of the testis. 7 of these patients received cytostatic treatment with MOPP and/or ABVD, 9 patients had a radiation treatment, 3 received both treatments. One patient remained free of further treatment.



Buserelin treatment was recommended to start at least 7 days prior to the tumor treatment, the interval ranged between 7 and 43 days. It ended on the same day as the tumor treatment or some days later, but this recommendation was followed only in 12 patients. 4 patients cessated buserelin treatment before end of the tumor therapy, and 4 other dropped out of the study.



Testosterone plasma levels were measured before, during and after treatment with buserelin. 7 days after starting they were increased in most patients, while they were lower after 14 days and at the end of treatment period.



Semen analysis showed sperm counts of 1 to 44 millions/ml with motility rates from 9 to 81%. In only ten patients we analysed a semen sample up to 6 months after cessation of treatment. In all but one we found azoospermia.



Thus this treatment at now cannot be recommended in young men undergoing cytotoxic treatment to preserve fertility.



Zusammenfassung: Wir behandelten 20 junge Manner wahrend einer Tumortherapie zusatzlich — nach entsprechender Aufklarung und mit ihrem Einverstandnis — mit dem GnRH-Agonisten Buserelin. 11 dieser Manner hatten einen Mb. Hodgkin, 2 ein non-Hodgkin Lymphom, 6 ein Seminom und 1 Patient ein embryonales Karzinom des Hodens. 7 der Patienten erhielten eine Cytostatica-Behandlung mit MOPP und/oder ABVD, 9 von ihnen wurden bestrahlt und 3 erhielten beide Behandlungen kombiniert. 1 Patient blieb nach der Operation frei von weiterer Tumorbehandlung.



Die Buserelin-Behandlung wurde nach Moglichkeit 7 Tage vor der Tumorbehandlung begonnen, der Abstand lag zwischen 7 und 43 Tagen. Sie sollte am gleichen Tag wie die Tumorbehandlung enden, diese Empfehlung konnte aber nur bei 12 Patienten befolgt werden. 4 Patienten beendeten die Buserelin-Behandlung vor dem Ende der Tumortherapie, vier weitere konnten nicht mehr beobachtet werden.



Vor, wahrend und nach der Buserelin-Behandlung wurden die Testosteron-Serumspiegel gemessen. Sie stiegen 7 Tage nach Beginn der Behandlung an und lagen nach 14 Tagen und am Ende der Behandlungsperiode unter den Ausgangswerten.



Die Ejakulatuntersuchung vor der Behandlung ergab Samenzelldichten von 1 bis 44 Mill/ml und Motilitatsraten von 9 bis 81%. Nur bei 10 Patienten konnte eine Samenprobe auch nach der Behandlung 6 Monate nach der Behandlung untersucht werden. Bis auf einen Patienten hatten alle eine Azoospermie. Derzeit kann also die Behandlung mit Buserelin bei jungen Mannern zum Schutz der Spermatogenese wahrend cytotoxischer Therapie nicht empfohlen werden.

Treatment with the Gonadotropin‐Releasinghormone Agonist Buserelin to Protect Spermatogenesis against Cytotoxic Treatment in Young Men/Behandlung zum Schutz der Spermatogenese bei cytotoxischer Therapie mit dem Gonadotropin‐Hormon Agonisten Buserelin

In adult rhesus monkeys a two- to threefold increase in the number of spermatogonia was found at Day 75 after 1 Gy of X-irradiation when the animals were pretreated with two intramuscular injections of follicle-stimulating hormone (FSH) each day. Also the percentage of cross-sections of seminiferous tubules showing spermatogonia (repopulation index) was much higher when FSH was given before irradiation. At 75 days postirradiation the repopulation index was 39 +/- 10% after irradiation alone and 81 +/- 11% when FSH pretreatment was applied. The pretreatment with two injections of FSH each day during 16 days caused an increase in the number of proliferating A spermatogonia. In view of earlier results in the mouse, where proliferating spermatogonial stem cells appeared more radioresistant than quiescent ones, it is suggested that the protective effects of FSH treatment are caused by the increase in the proliferative activity of the A spermatogonia and consequently of the spermatogonial stem cells. The results indicate that in the rhesus monkey the maximal protective effect of FSH is reached after a period of treatment between 7 and 16 days.

https://cancerres.aacrjournals.org/content/canres/49/3/533.full.pdf

Protection from Radiation-induced Damage of Spermatogenesis in the Rhesus Monkey (Macaca mulatta) by Follicle-stimulating Hormone

This study evaluates the effect on spermatogenesis of coadministration of Cytoxan (cyclophosphamide) and nafarelin, a luteinizing hormone-releasing hormone agonist. Nafarelin causes complete aspermatogenesis in dogs by interrupting the hypothalamic-pituitary-gonadal axis, which might protect against the testicular cytotoxicity associated with cyclophosphamide. The four treatment groups, each consisting of 2 mature male beagle dogs, were ( a ) no drug; ( b ) cyclophosphamide (p.o. 3x weekly for 43 and 48 wk for a total dose of 582 and 709 mg/kg, with dose varying according to weekly hematological profile); ( c ) nafarelin (2 µg/kg s.c. daily for 48 and 52 wk); and ( d ) cyclophosphamide plus nafarelin [same schedule as above with cyclophosphamide (570 and 698 mg/kg total dose) starting 7 wk after beginning nafarelin]. Plasma testosterone, spermatogenesis, and ejaculate volume were completely suppressed by nafarelin prior to starting cyclophosphamide. By 2 wk after cessation of treatment (posttreatment, PT), plasma testosterone reached normal levels, and at 5 wk PT ejaculates appeared which reached normal volumes 2 to 3 wk later. Normally motile ejaculated spermatozoa were noted at 6 to 8 wk PT in nafarelin-only-treated animals; normal sperm numbers were reached at 14 wk PT. The animals receiving cyclophosphamide plus nafarelin were azoospermic for the entire 65-wk PT period, and at 65 wk PT no germinal cells were found upon evaluation of testicular histology. Sperm numbers in cyclophosphamide-only-treated animals began to rise 10–11 wk PT and reached 150 × 10 6 sperm/ejaculate at approximately 65 wk PT (contemporaneous control dogs had sperm numbers of approximately 300–600 × 10 6 /ejaculate). Spermatogenesis in these cyclophosphamide-only-treated animals was normal in most seminiferous tubules at this time. The addition of nafarelin to cyclophosphamide treatment thus exacerbated the deleterious effects of cyclophosphamide on the testes, suggesting caution for use of such a protocol clinically.

Potentiation of the Gonadotoxicity of Cytoxan in the Dog by Adjuvant Treatment with a Luteinizing Hormone-releasing Hormone Agonist

The ability of androgen pretreatment in adult Wistar rats to protect the spermatogonial stem cells from one or two doses of the cytotoxic procarbazine (PCB) was investigated. Survival of stem cells was assessed by a tubule regeneration assay. Ten weeks' pretreatment of the rats with 200 mm2 silastic implants containing testosterone resulted in significant protection of the spermatogonial stem cells from PCB-induced damage. Androgen-pretreated rats given a single dose of 200 mg/kg PCB demonstrated 86% tubule regeneration as opposed to 41% in rats pretreated with cholesterol. Similar values were obtained when the PCB dose was given as two weekly fractions of 100 mg/kg. The protective effect of androgen is present from the time of the initial challenge with the cytotoxic drug.

J I Delic

Papers

Protection of Spermatogenesis During Cancer Chemotherapy