Testosterone Pellets Research Articles

Investigation of suppression of the hypothalamic-pituitary-gonadal axis to restore spermatogenesis in azoospermic men treated for childhood cancer.

Does suppression of the hypothalamic-pituitary-gonadal (HPG) axis restore spermatogenesis in men rendered azoospermic following treatment of childhood cancer? Seven men with azoospermia secondary to treatment for childhood cancer, median age (range), 22.2 (18-25.3) years, aged 10.4 (4.4-13.3) years at original diagnosis, participated. Each subject underwent semen analysis and testicular biopsy, followed by treatment with medroxyprogesterone acetate (MPA), 300 mg i.m. repeated after 12 weeks, with 800 mg testosterone pellets s.c. on day 1 to suppress the HPG axis. Hormone and semen analysis was performed every 6 weeks for 48 weeks. A second testicular biopsy was performed at week 48. Before HPG axis suppression, mean +/- SEM plasma LH was 9.0 +/- 1.8 U/l, testosterone 17.9 +/- 1.5 nmol/l and FSH 22.4 +/- 4.4 U/l. Median (range) venous plasma and seminal plasma inhibin B levels were 10.0 (7.8-35) and 11.2 (7.8-770) ng/l respectively. During HPG suppression, FSH and LH levels were undetectable for > or =12 weeks followed by a gradual return to pretreatment concentrations by 48 weeks. All men remained azoospermic at study completion and complete absence of germ cells on biopsies was demonstrated by immunocytochemistry for all specimens pre- and post-HPG axis suppression. HPG axis suppression with MPA-testosterone for > or =12 weeks did not restore spermatogenesis in azoospermic men treated with gonadotoxic radiotherapy and chemotherapy for childhood cancer.

Redefining gonadotropin-releasing hormone (GnRH) cell groups in the male Syrian hamster: testosterone regulates GnRH mRNA in the tenia tecta.

Gonadotropin-releasing hormone (GnRH) regulates the production of testosterone via the hypothalamic-pituitary-gonadal axis and testosterone, in turn, regulates the GnRH system via negative feedback. We compared testosterone regulation of GnRH mRNA expression in four anatomically defined GnRH cell groups in juvenile and adult male Syrian hamsters, including a rostral population of GnRH cells in the tenia tecta. In situ hybridization histochemistry (ISHH) was used to measure GnRH mRNA in brains from castrated juveniles and adults treated with 0 mg or 2.5 mg testosterone pellets for one week. ISHH was performed on coronal sections using a 35S-cRNA probe generated from Syrian hamster GnRH cDNA. Testosterone treatment resulted in a significant reduction in mean area of GnRH neurones covered by silver grains within the tenia tecta, but only a trend toward decreased GnRH mRNA in the diagonal band of Broca/organum vasculosum of the lamina terminalis (DBB/OVLT), medial septum (MS), and caudal preoptic area (cPOA). The effects of testosterone were independent of age. Frequency distribution analyses unveiled a significant reduction in the number of heavily labelled cells following testosterone treatment within the tenia tecta and MS. Simple regression analyses revealed a significant positive correlation between plasma luteinizing hormone concentrations and GnRH mRNA only in the tenia tecta. These data indicate that, overall, GnRH mRNA is modestly reduced by testosterone, and the most robust attenuation of GnRH mRNA occurs within the tenia tecta. This is the first report to link mechanisms of steroid negative feedback with tenia tecta GnRH neurones, providing a new focus for investigating brain region-specific steroidal regulation of GnRH synthesis.

Testosterone increases neurotoxicity of glutamate in vitro and ischemia-reperfusion injury in an animal model.

Increasing evidence has demonstrated striking sex differences in the outcome of neurological injury. Whereas estrogens contribute to these differences by attenuating neurotoxicity and ischemia-reperfusion injury, the effects of testosterone are unclear. The present study was undertaken to determine the effects of testosterone on neuronal injury in both a cell-culture model and a rodent ischemia-reperfusion model. Glutamate-induced HT-22 cell-death model was used to evaluate the effects of testosterone on cell survival. Testosterone was shown to significantly increase the toxicity of glutamate at a 10 microM concentration, whereas 17beta-estradiol significantly attenuated the toxicity at the same concentration. In a rodent stroke model, ischemia-reperfusion injury was induced by temporal middle cerebral artery occlusion (MCAO) for 1 h and reperfusion for 24 h. To avoid the stress-related testosterone reduction, male rats were castrated and testosterone was replaced by testosterone pellet implantation. Testosterone pellets were removed at 1, 2, 4, or 6 h before MCAO to determine the duration of acute testosterone depletion effects on infarct volume. Ischemic lesion volume was significantly decreased from 239.6 +/- 25.9 mm(3) in control to 122.5 +/- 28.6 mm(3) when testosterone pellets were removed at 6 h before MCAO. Reduction of lesion volume was associated with amelioration of the hyperemia during reperfusion. Our in vitro and in vivo studies suggest that sex differences in response to brain injury are partly due to the consequence of damaging effects of testosterone.

Estrogen replacement therapy in women with previous breast cancer

Objective: We sought to review the status of patients with breast cancer who were treated with estrogen replacement therapy and compare the results with those of nonestrogenic hormone users and women not treated with hormone replacement. Study Design: The study group consisted of 76 patients with breast cancer, including 50 using estrogen replacement for up to 32 years, 8 using nonestrogenic hormone replacement for up to 6 years and followed for up to 11 years, and 18 using no hormones for up to 10 years. In addition to estrogen use, 40 of the 50 hormone users were treated with androgens, usually in the form of implantation of testosterone pellets. Forty-five subjects were also given progestogens, usually megestrol acetate 20 to 40 mg for 10 to 25 days each month. The 8 nonestrogen hormone users were treated with various combinations of testosterone pellets, tamoxifen, and progestogens. Forty-two of the 50 estrogen users are still being treated in our clinic, as are 2 of the 8 subjects using nonestrogen hormone. Follow-up was done through the tumor registry at University Hospital, and those whose tumor records were not current were telephoned. Results: Of the 50 estrogen users, 3 have died (a mortality rate of 6%), and the rest have been followed for 6 months to 32 years, with a mean duration of follow-up of 83.3 ± 8.81 months. One of the 8 nonestrogen hormone users has died (a mortality rate of 12.5%), and the rest have been followed for 2 to 11 years, with a mean duration of follow-up of 72.0 ± 5.93 months. Six of the 18 women not using hormone replacement have died (a mortality rate of 33.3%), and the rest have been followed for 6 months to 10 years, with a mean duration of follow-up of 50.5 ± 6.01 months. Conclusion: Estrogen replacement therapy apparently does not increase either recurrences or mortality rates. Adding progestogens may even decrease recurrences. Women with early breast cancer should be offered hormone replacement therapy after a full explanation of the benefits, risks, and controversies. (Am J Obstet Gynecol 1999;181:288-95.)

Androgenic regulation of growth factor and growth factor receptor expression in the CWR22 model of prostatic adenocarcinoma.

The effects of androgen manipulation on epidermal growth factor (EGF) receptor, p185erbB-2 and transforming growth factor-alpha (TGF-alpha) levels were examined in prostatic adenocarcinoma. Male nude mice were inoculated with the CWR22 androgen-dependent human prostatic tumor or an androgen-independent (CWR22R) derivative. Mice with CWR22 tumors were castrated and subsequently killed at 3, 7, 21, 28 or 42 days post-castration. Other CWR22-bearing mice received s.c. testosterone pellets at 21 days post-castration and were killed 7 days later. EGF receptor, p185erbB-2 and TGF-alpha levels were examined by immuno-histochemistry. Strong EGF receptor and p185erbB-2 immunostaining was detected in CWR22 tumors from intact controls. EGF receptor immunostaining decreased by 65% to 70% at 21 to 42 days post-castration. Testosterone treatment at 21 to 28 days post-castration resulted in a 2-fold increase in EGF receptor immunostaining. p185erbB-2 immunostaining within CWR22 tumors did not decrease following castration and, in fact, was slightly increased at 7 days post-castration. The effects of castration on EGF receptor and p185erbB-2 levels were confirmed by Western blot analysis. Fewer than 10% of CWR22 tumor cells demonstrated strong TGF-alpha immunostaining, and androgen manipulation did not effect TGF-alpha immunostaining. In contrast, 30% of androgen-independent CWR22R tumor cells were strongly immunostained for TGF-alpha. Our findings indicate that EGF receptor levels, but not p185erbB-2 levels, are strongly dependent on testosterone in CWR22 tumors. The co-localization of TGF-alpha and the EGF receptor in CWR22R tumors suggests that these factors may constitute an autocrine pathway that regulates androgen-independent growth.

Sexual differentiation of oestradiol-LH positive feedback in a marsupial.

The surge of LH that induces ovulation in mammals showing spontaneous ovulation is precipitated by the positive feedback of increasing oestrogens from the developing follicles in the ovary. In eutherians, exogenous oestrogens can mimic this effect by eliciting an LH surge in females, but not usually in males. The absence of a positive LH response to eutherian males is either due to an acute suppression by the secretory products of the testes during adulthood or the permanent disabling of the system by testosterone during early development. This phenomenon is examined in tammar wallabies, Macropus eugenii. The results show that the oestradiol-LH positive feedback response is sexually dimorphic in this marsupial. A surge in plasma LH occurred between 15 and 28 h after injection of 2.5 micrograms oestradiol benzoate kg-1 in 13 of 16 intact females and 4 of 4 ovariectomized females, but in none of 11 intact males. Five females each implanted with a 100 mg testosterone pellet 3 months earlier failed to produce an LH surge. Four males castrated in adulthood and three adult males castrated before puberty also failed to show an LH surge. However, three males castrated 24-26 days after birth showed an unambiguous LH surge when challenged with oestradiol benzoate during adulthood. Thus, in tammar wallabies, the ability to generate an LH surge to oestradiol is a sexually dimorphic response that is suppressed in the male by the organizational effects of the testes in early life and presumably supplemented by an inhibitory effect of circulating testosterone in adulthood.

CHANGES IN CYCLIN DEPENDENT KINASE INHIBITORS p21 AND p27 DURING THE CASTRATION INDUCED REGRESSION OF THE CWR22 MODEL OF PROSTATIC ADENOCARCINOMA

Purpose The expression of the cyclin dependent kinase inhibitors p21 and p27 was examined in prostatic adenocarcinomas following castration. Materials and Methods Male nude mice inoculated with the androgen dependent human prostatic tumor CWR22 were castrated when the tumors reached a volume of 0.8 to 1.1 cm. 3 and were sacrificed at 3, 7, 21, 28 and 42 days post-castration. An additional group of mice received a subcutaneous testosterone pellet at 21 days post-castration and was sacrificed at 28 days post-castration. The expression of the Ki-67 antigen, p21 and p27 was examined by immunohistochemistry. Results The mitotic rate as well as the number of Ki-67 antigen positive cells decreased to 3% of intact control values by 7 days post-castration and were less than 0.01% of intact control values at 21, 28 and 42 days post-castration. The percentage of p21 expressing cells decreased from 15 +/− 2% in intact controls to less than 1% by 42 days post-castration. In contrast, the percentage of cells that expressed p27 increased from 25 +/− 3% in intact controls to 51 +/− 8% at 3 days post-castration and to 80 to 95% at days, 7, 21, 28 and 42 days post-castration. Testosterone treatment from 21 to 28 days post-castration resulted in an increase in Ki-67 antigen positive cells to 200% of intact controls and a concomitant reduction in p27 expressing cells to about 50% of intact controls. Castration-induced changes in p27 expression were not observed in the CWR22R tumor, a transplantable relapsed derivative of the CWR22 tumor. Conclusion These findings suggest that p27 expression is regulated negatively by androgens and that increased expression of p27 in CWR22 xenografts may be involved in the suppression of proliferation following castration.

An analysis of testosterone implants for androgen replacement therapy.

To review 13 years of experience using fused crystalline testosterone implants for androgen replacement therapy in order to identify pattern of usage (including continuation rates) and adverse events emerging during therapy and factors associated with adverse events including implant extrusions. Retrospective review of prospectively collected data on characteristics of patients and implant procedures performed as well as adverse events reported during routine follow-up. Over 13 years 973 implant procedures using fused crystalline testosterone implants were performed in 221 men. Continuation rates and adverse events such as extrusions, bleeding, infection or others were recorded and analysed in relationship to characteristics of the patient and the implant procedure performed. Overall rate of adverse events (108/73, 11.1%) was significantly related to increased numbers of implants (4.2 +/- 0.1 vs 4.0 +/- 0.03, P = 0.031) and higher levels of physical activity at work (P = 0.030). The most common adverse effect was extrusion (83/973, 8.5%) which was related to occupational classification (P = 0.033) and increasing work activity (P = 0.044) and occurred more frequently than by chance in multiple (16 vs 3.3 expected) rather than single (65 vs 76.1 expected) episodes. Bleeding (22/973, 2.3%) was significantly associated with an increased number of implants (4.5 +/- 0.2 vs 4.0 +/- 0.03, P = 0.020) but even in the worst cases (3/22) it was of minor clinical importance. Infection was rare (6/973, 0.6%) but occurred more among thinner men. The overall continuation rate was 92.7% increasing from 86% after the first implantation to > 99% after the tenth implant. This study demonstrates the very satisfactory clinical acceptability of testosterone pellet implants for androgen replacement therapy within a single unit with experienced operators. The only regular adverse effect is extrusion, which may be related to mechanical factors such as habitual work activity but also possibly procedural factors. Other adverse effects such as bleeding, infection and fibrosis were rare. An improved method of implant delivery would enhance this old but durable technology.

Treatment of hypogonadal adolescent boys with long acting subcutaneous testosterone pellets

AIMSLong acting subcutaneous testosterone pellets are of proved efficacy for the treatment of hypogonadal men, but have not been reported as a treatment modality in adolescent boys. Pharmacodynamic studies of...

Mouse anococcygeus muscle: sexual dimorphism and responsiveness to sex hormones.

The anococcygeus muscle (AcM) is one of a pair of thin sheets of smooth muscle inserting on the rectum, having a tendinous origin largely on sacral vertebrae. The cross-sectional area of AcM in the juxtarectal region in 90-day-old male mice was significantly larger than that in females of three strains: BALB/cCrgl, ICR/Jcl and C57BL/Tw. The AcM area in female mice showed strain differences: BALB/c > ICR > C57BL. Five daily injections of testosterone into newborn ICR mice from the day of birth significantly increased the areas of AcM in both sexes at 30 days of age, but five daily injections of oestradiol-17 beta (OE) decreased them. The AcM area in 60-day-old ICR male mice castrated at 30 days of age was significantly smaller than in intact males, and that in ovariectomized females was significantly larger than in intact females. In both sexes, implantation of a testosterone pellet (12 mg) into gonadectomized mice on the day of gonadectomy stimulated the growth of AcM, and implantation of an OE pellet (12 mg) inhibited the growth of AcM. The AcM in both ICR and C57BL strains showed positive androgen receptor and oestrogen receptor immunostaining at 15 days. Female ICR mice exposed neonatally to diethylstilboestrol (DES) had significantly larger AcM than controls; ovariectomy at 30 days of age did not change the AcM area in 60-day-old DES-exposed mice. However, male mice exposed neonatally to DES had significantly smaller AcM than controls; castration at 30 days of age nullified this inhibition. These results suggest that both androgen and oestrogen play an important role in sexual dimorphism of the mouse AcM. Neonatal exposure to DES (but not to oestradiol) had an irreversible stimulatory effect on the AcM area in female mice.

Pharmacokinetics and pharmacodynamics of subcutaneous testosterone implants in hypogonadal men.

There are advantages and disadvantages with all of the presently available types of testosterone replacement for hypogonadal men. We performed this investigation to establish detailed data about the pharmacokinetics, pharmacodynamics, feasibility and side-effects of subcutaneously implanted testosterone (T) pellets. In a single-dose, open-label, non-randomized study, 6 T-pellets, each containing 200 mg of fused crystalline T, were implanted in the subdermal fat tissue of the lower abdominal wall of 14 hypogonadal men. Blood samples for determination of T, LH, FSH, 5 alpha-dihydrotestosterone (DHT), sex hormone binding globulin (SHBG) and oestradiol (E2) were obtained at 0, 0.5, 1, 2, 4, 8, 12, 24, 36, 48 hours and on day 21 after implantation and then every 3 weeks until day 189, and on days 246 and 300 during follow-up. In another 36 hypogonadal men the feasibility and side-effects of T-pellets were evaluated. Fourteen patients participated in the detailed pharmacokinetic study and another 36 patients in the assessment of feasibility and side-effects. All patients (age range 18-61 years) suffered from primary or secondary hypogonadism (T < 3.6 nmol/l). The pharmacokinetic study in 14 hypogonadal men revealed an initial short-lived burst release of T with a peak concentration of 49.0 +/- 3.7 nmol/l at 0.5 +/- 0.13 days which was followed by a stable plateau lasting until day 63 (day 2, 35.2 +/- 2.3; day 63, 34.8 +/- 2.6 nmol/l). Thereafter serum T gradually declined and was close to baseline concentrations on day 300. Apparent terminal elimination half-life (t1/2) was 70.8 +/- 10.7 days and apparent mean residence time 87.0 +/- 4.5 days. On average, serum T was below 10 nmol/l after 180 days. Absorption of T followed a zero-order release kinetic with an absorption half-time of 74.7 days (95% confidence interval: 71.1-78.5) and was almost complete by day 189 (95.9 +/- 0.84%). Serum DHT and E2 were significantly elevated from day 21 to day 105 and correlated significantly with T (DHT, r = 0.65, P < 0.0001, E2, r = 0.67, P < 0.0001). SHBG was significantly decreased from day 21 to day 168. In 6 men with primary hypogonadism T suppressed LH and FSH to the eugonadal range from day 21 to 126 and 42 to 105, respectively, with nadirs occurring at day 84 (LH) and day 63 (FSH). LH and FSH were highly inversely correlated with T (r = -0.47 and -0.57). The only side-effect observed during 112 implantations in the total group of 50 men were 6 local infections (5.4%) leading to extrusion of 5 pellets in 3 men. When given the choice, all patients except one preferred T-pellets to their previous T medication for permanent substitution therapy. T-pellets are the androgen formulation with the longest biological action and strongest pharmacodynamic efficacy in terms of gonadotrophin suppression. The pharmacokinetic features are advantageous compared to other T preparations and the patient acceptance is high.

Androgenic control of 1-alkyl-2,3-diacylglycerol in the harderian gland of the golden hamster, Mesocricetus auratus.

Harderian glands of golden hamsters produce a copious lipid secretion, most of which is in the form of 1-alkyl-2,3-diacylglycerol (ADG). Sexual differences are seen in the composition of golden hamster ADG and in the morphology of secretory lipid droplet. ADGs from females contained abundant iso- and anteiso-branched chain alkyl groups and fatty acids [Seyama, Y., Otsuka, H., Ohashi, K., Vivien-Roels, B., and Pevet, P. (1995) J. Biochem. 117, 661-670]. Female hamsters were either untreated or given subcutaneous testosterone pellets. Treatment of females with testosterone led to the disappearance of such branched chain alkyl groups and fatty acids. Intact males had ADGs with entirely saturated straight chain alkyl groups and fatty acids. Castration led to the appearance of iso- and anteiso-branched chain alkyl groups and fatty acids. These observations suggested that the production of branched chain fatty acids in the Harderian gland of golden hamster is inhibited by testosterone at the step of isovaleryl-CoA dehydrogenase and 2-methyl branched-chain acyl-CoA dehydrogenase

Testosterone on Turkey Growth: 2. Effects of Castration and Testosterone Implant on Carcass Yield, Carcass Conformation and Chemical Composition.

Effects of castration and testosterone implants on carcass yield, carcass conforma-tion, body composition, and chemical composition of edible meats in male turkeys were determined. A2×2 factorial arrangement of treatments with testosterone implant and castration was incorporated in experimental design. Male turkeys were castrated at 9.5 weeks of age and implanted with testosterone pellets at 20mg/kg body weight at 11 weeks of age. Six turkeys from each treatment were killed at 21 weeks of age to determine the carcass quality and the chemical composition. The yield of eviscerated carcasses was increased (P≤0.05) by testosterone treatment (T), but not affected by castration (C). Abdominal fat was reduced (P≤0.05) by T, but not affected by C. The amount of skin was incresed (P≤0.05) by T and decreased (P≤0.05) by C. The wing yield was reduced (P≤0.05) by T and increased (P≤0.05) by C. The part and lean yields were not affected by either T or C with the following exceptions. The lean yield of breast was increased (P≤0.05) by T and the part and lean yields of drumsticks were reduced (P≤0.05) by C. Body composition was affected (P≤0.05) by T, but not by C. The moisture content was increased (P≤0.05) by T. The chemical composition of breast, thigh, and drumstick was not affected by either T or C with an exception that the moisture content of breast meat was increased (P≤0.05) by T.

Androgens regulate circulating levels of insulin-like growth factor (IGF)-I and IGF binding protein-3 during puberty in male baboons.

To examine the role of androgens in initiating the pubertal rise in circulating insulin-like factor-I (IGF-I) levels, a longitudinal study of puberty in 13 male hamadryas baboons was conducted over 3 yr. The five control baboons commenced puberty (initial testicular enlargement) at a mean +/- SE age of 4.2 +/- 0.4 yr. Another eight baboons were castrated prepubertally; of those four received testosterone pellets (dose equivalent: 12.5-50 mg every 6 weeks) implanted se from the time of puberty. Body weight, crown-rump length, and limb length measurements, synchronized to pubertal onset, suggest that a pubertal growth spurt occurs in male baboons. Control baboons had a marked rise (4- to 5-fold; P < 0.0001) in circulating IGF-I levels; maximum IGF-I levels (168 +/- 9 nmol/L) were reached 42 months after the onset of puberty (mean chronological age 7.5 yr). Castrated baboons had no significant rise in IGF-I levels, however, administration of testosterone resulted in a close approximation of the normal pubertal rise in IGF-I (maximum values 140 +/- 8 nmol/L), confirmed by comparison of fitted sigmoid curves (r2 > 0.99; chronological age ED50 controls, 4.4 +/- 0.1 yr and castrate + testosterone, 4.3 +/- 0.1 yr). Serum IGF binding protein-3 levels paralleled the rise in IGF-I consistent with a common regulatory mechanism. In another study, castration of four sexually mature male baboons aged 11.12 +/- 1.16 yr had no effect on serum IGF-I levels (P = 0.5). This indicates that androgens are the predominant determinant of circulating IGF-I in the male baboon, and that this is an uniquely pubertal phenomenon.

Progesterone enhancement of stomach tumor development in SD rats treated with N-methyl-N'-nitro-N-nitrosoguanidine.

The effects of chronic progesterone treatment on gastric tumorigenesis were examined in 6‐week‐old male SD rats. The rats were castrated, progesterone or testosterone pellets were implanted, and, starting one week after the operation, 100 mg/liter of N‐methyl‐N‐nitro‐N'‐nitrosoguanidine (MNNG) was administered in the drinking water for 16 weeks. Every 2 months the pellets were changed. Group 1 animals received castration plus MNNG while Groups 2 and 3 also received progesterone and testosterone, respectively. In the Group 4 case, progesterone and testosterone were administered alternately for 2‐month periods and in Group 5 MNNG was given to intact animals. All survivors were killed one year after the start of MNNG treatment. In Group 1 the incidence of gastric tumors was significantly decreased as compared with the Group 5 value. The Group 2 incidence, in contrast, was similar to that in Group 5, and the size of the observed gastric tumors was massively increased. The area of the pyloric gland mucosa was also greater than in other groups. Testosterone treatment was associated with a less pronounced increase in tumor size and a recovery in incidence. The results indicate that progesterone may exert a promoting influence on gastric tumor development.

INHIBITORY EFFECT OF TRANSIENT ADMINISTRATION OF FLUTAMIDE (SCH-13521, 4'-NITRO-3'-TRIFLUOROMETHYLISOBUTYRANILIDE) ON DIETHYL-NITROSAMINE (DEN) INDUCED LIVER-TUMORS IN MALE B6C3F1 MICE

In order to understand the role of androgen in DEN induced liver tumorigenesis in mice, we studied the influence of anti-androgenic compound, flutamide (SCH 13521, 4'-Nitro-3'-trifluoromethylisobutyranilide) on liver tumors, in B6C3F1 male mice. At 6 weeks of age mice were treated with DEN, (0.2 muM/g body weight). Transient administration of flutamide (0.5 mg/g food) in diet to male mice for (i) three weeks immediately after diethylnitrosamine (DEN) treatment, for (ii) three weeks starting at the age of 25 weeks and (iii) starting at 25 weeks of age until end of experiment inhibited liver tumors incidence to 63%, 50% and 53%, respectively, compared to that of DEN alone, 81.3% (significantly different). However, continuous administration of this drug throughout the experimental period (58 weeks) produced 96.9% liver tumor incidence. The time-dependent sacrifice of DEN alone treated mice at 25, 30, 38, 44 and 58 weeks of age produced liver tumor incidence of 0, 12.5, 31.5, 43.8 and 81.3%, respectively (r = 0.99). Mean tumor number and size were also correlatively increased with the prolongation of latency and highest value was noted at 58 weeks of age. Implantation of testosterone pellet after castration significantly increased cytosolic androgen receptor levels but decreased in mice treated with flutamide. Three weeks administration of flutamide to male B6C3F1 mice enhanced nuclear BrdU incorporated cells in the liver. Our results suggested that flutamide reduces cytosolic androgen receptor levels and increases DNA synthesis. These factors may in part be responsible for the liver tumor inhibitory effect of flutamide in male mice.

Pineal acid phosphatase activity in Syrian hamsters: sex differences and effects of castration and androgen replacement therapy.

Pineal acid phosphatase (ACP) activity was examined in seven experiments involving young intact or castrated male and female Syrian hamsters. Nine-week old female hamsters had a 3-fold (p < 0.001) higher ACP activity in their pineal glands than did males. After three weeks of castration, a significant increase (p < 0.001) in ACP activity occurred in castrated male pineal glands. In males, pellets with 5 alpha-dihydrotestosterone (p < 0.01) but not testosterone or progesterone suppressed pineal ACP activity. In females, no changes in pineal ACP activity were noted due to the estrous cycle. Pineal ACP activity was not affected by testosterone, dihydrotestosterone or androstenedione pellets in intact females or by testosterone pellets in ovariectomized animals.

Xenografts of primary human prostatic carcinoma.

Prostatic carcinoma is both the most common invasive cancer and the second most common cause of cancer deaths in men in the United States. Before 1991, attempts to propagate prostatic carcinoma from primary tumors for periods longer than 3 months were unsuccessful in vivo and in vitro with rare exceptions. In 1991, we reported establishment of slowly growing tumors for six of 10 human primary prostatic carcinomas approximately 2-6 months after transplantation. However, none of the tumors were larger than 5 mm or serially transplantable. Our purpose in this study was to determine whether human primary prostatic carcinoma could be grown as serially transplantable xenografts. Cells from primary prostatic carcinomas obtained from transurethral prostatic resections or total prostatectomies in 20 patients were injected subcutaneously into male nude mice on the day of surgery. Sustained-release testosterone pellets were placed subcutaneously in the mice 2-24 days before transplantation of tumors and at intervals of 10-12 weeks. Serial transplantations in subsequent generations of mice were carried out by similar methods. Chromosome analysis was performed on six tumors. Six of 20 primary prostatic carcinomas have grown sufficiently to permit serial transplantation into second mice; four have been documented histopathologically in the second mouse and serially transplanted into three or more successive mice. When a single primary tumor was injected into several mice by the same procedure, tumors failed to grow in some recipients but became serially transplantable in others. Growth of these tumors is slow and irregular, with frequent regressions. Short-term cultures of 10 tumors, eight of which were injected into mice in parallel, were initiated on the day of surgery; CWR31, which was successfully transplanted serially, exhibited only aberrant metaphases and showed clonal, chromosomal changes in culture. Including CWR31, three of the six tumors for which chromosomal analysis was successful contained clonal aberrations. Preliminary studies of SCID (severe combined immunodeficient) mice suggest that they are not superior to nude mice for establishment of serially transplantable prostatic carcinoma xenografts. A proportion of human primary prostatic carcinomas can be grown as xenografts. Four new serially transplantable xenografts (CWR21, CWR31, CWR91, and CWR22) are currently propagated in our laboratory, a resource that was not previously available. Our experience suggests that the most important factor in serial transplantation is the collaboration of urologists and pathologists in expediting placement of the tumor in cold saline, examination of the frozen section, and transplantation.

Testosterone sensitive dihydropyridine binding in the Harderian gland of the male hamster

It is well known that in different tissues, dihydropyridines bind at nanomolar concentrations to a receptor and block voltage-operated Ca 2+ channels. In studies reported here, Harderian gland tissue homogenates from intact male hamsters exhibited significant dihydropyridine binding (B max = 1700 fmoles/mg protein) of high affinity (K d = 1.1 nM). Tissue homogenates from female animals exhibited a similar K d value (1.35 nM) but receptor density per mg protein was significantly reduced (B max = 270 fmoles). Dihydropyridine binding of Harderian gland tissue homogenates from castrated males was reduced greater than 80% (B max = 225 fmoles/mg protein). Treatment of castrated males with subcutaneous testosterone pellets resulted in significant restoration of dihydropyridine binding activity (approximately 80%, B max = 1630 fmoles/mg protein) with a comparable binding constant (K d = 1.50 nM) as observed for noncastrated, control animals. Addition of testosterone (ex vivo) to homogenates from castrated hamsters did not restore dihydropyridine binding to control levels. These data indicate: (a) the Harderian gland from male hamsters exhibits significant dihydropyridine binding; (b) ligand binding is abolished following castration; and (c) significant restoration of dihydropyridine binding occurs following in vivo testosterone treatment. The dependence of dihydropyridine binding restoration upon in vivo steroid hormone administration suggests probable involvement of the steroid at the transcriptional level although non-genomic mechanisms such as the binding of testosterone to a receptor resident in the plasma membrane and subsequent activation of Ca 2+ channels can not be ruled out.

A cross-sectional study of the effects of long-term percutaneous hormone replacement therapy on bone density

The effect of hormone implants on the bone density of postmenopausal women was studied in 110 patients (mean age 54.7 years; mean menopausal age 8.6 years, range 2-30) who had received hormone replacement in the form of estradiol (50-75 mg) and testosterone (100 mg) pellets at 6-month intervals for 2-24 years (mean 5.2). They were compared with 254 untreated women (mean age 55.0 years; mean menopausal age 6.8 years, range 1-37). The bone density at the spine, measured by quantitative digital radiography, was 1.123 grams hydroxyapatite (gHa)/cm2 in the treated group and 0.951 gHa/cm2 in the controls (P less than .0001). The total bone density at the proximal femur was 1.002 gHa/cm2 in the treated group, compared with 0.914 gHa/cm2 in the controls (P less than .0001). There were significant differences in the density of the trochanteric, intertrochanteric, and neck areas of the proximal femur as well as the Ward triangle (all P less than .0001). These differences became significant from the age of 55 at the neck of the femur, Ward triangle, and lumbar spine, and from age 60 for all other values. Subcutaneous estradiol and testosterone prevent postmenopausal osteoporosis and maintain normal bone density for as long as treatment is continued.