Endocrinologia experimentalis最新文献

Granulosa cells were recovered from small (1-3 mm in diameter) and large (greater than 6 mm in diameter) preovulatory follicles or from follicles of early pregnant pigs (3-5 mm, Day 18). Incubation of these cells (5 x 10(5)) was carried out in a shaking water bath (40 degrees C) for 2 h with or without salbutamol (10(-5) M), isoprenaline (10(-5) M), propranolol (10(-5) M) and FSH (100 ng/ml). Isoprenaline significantly increased progesterone production (P less than 0.05) by granulosa cells of small follicles and large preovulatory follicles but not by granulosa cells of follicles from early pregnant pigs. After blocking the beta-adrenoceptor with propranolol the stimulatory effect of catecholamines was not observed. FSH alone stimulated progesterone production, particularly in granulosa cells of early pregnant pigs (P less than 0.05) but FSH plus catecholamine treatment did not have any effect on progesterone release. These results suggest that catecholamines may play a regulatory role in follicle maturation and this may differ between naturally cyclic and early pregnant animals.

The influence of varying glucoregulatory states as induced by fasting, feeding and intravenous glucose infusion on liver thiol content has been assessed in the male rat. As expected, increasing the serum glucose levels from 131 +/- 7 mg/dl to 343 +/- 12 mg/dl (mean +/- S.E.) caused a corresponding increase in serum insulin responses. Rising from 3.2 +/- 0.4 mumol/g w.w. in the fasted group to a peak value of 6.3 +/- 0.4 mumol/g (P less than 0.01) in the group infused by 10% glucose solution, hepatic non protein bound sulphydryl groups (NP-SH) were closely related to serum glucose levels up to 244 +/- 11 mg/dl. When higher glucose doses were infused. NP-SH values fell steadily, they even inclined below the level of the fasted rats after infusion of 30% and 40% glucose solutions (1.3 +/- 0.4 mumol/g w.w., P less than 0.05 and 0.7 +/- 0.3, P less than 0.01, resp.), mean serum glucose levels being 291 +/- 12 and 343 +/- 13 mg/dl, resp. Hepatic protein bound thiols were not affected by any of the glucoregulatory states experimentally induced. The data demonstrate that the glucoregulatory state influences hepatic NP-SH content divergently. The study suggests that under physiological conditions liver NP-SH content covariates positively with serum insulin and glucose levels.

The effects of large doses of thyroid hormone, thyrotropin (TSH) or thyrotropin-releasing hormone (TRH) on pro-TRH concentrations in the rat hypothalamus, cerebrum, cerebellum, brain stem, stomach and eye were studied. The rats were administered T4 (2.5 mg/kg), T3 (375 micrograms/kg), TRH (1.0 mg/kg) or bovine TSH (1.25 IU/kg) i.p. and seven rats in each subgroup were decapitated at 4 or 24 h after the injection. Pro-TRH, TRH, TSH and thyroid hormone were measured by each radioimmunoassay. Immunoreactive pro-TRH (ir-pro-TRH) and immunoreactive TRH (ir-TRH) were found in the hypothalamus, cerebrum, brain stem, stomach and eye. Ir-pro-TRH concentrations in the hypothalamus decreased significantly after T4 and T3 injection and tended to decrease after TRH and TSH injection, but not significantly. In contrast, ir-pro-TRH concentrations in other tissues showed no changes after T4, T3, TRH or TSH injection. Ir-TRH concentrations in tissues did not change significantly after these hormone injection. The plasma TSH levels decreased significantly, while these of thyroid hormone increased significantly after thyroid hormone injection. Elution profile of acetic acid extracts of hypothalamus, stomach or eye was identical to that of synthetic pro-TRH. The findings suggest that the large dose of thyroid hormone inhibits pro-TRH synthesis in the hypothalamus, and that TRH synthesis in the tissues except the hypothalamus may not be regulated by thyroid hormone.

In previous studies, follicular fluid (FF) of large antral follicles (LFF) manifested a stimulatory effect on granulosa cell (GC) luteinization in domestic livestock, but was found to have an inhibitory effect on rodent GC. In the present study, the type of LFF effect on the luteinizing of rat GC was reevaluated in two different models. GC obtained from immature hypophysectomized rats treated with diethylstilbestrol were cultured with increasing concentrations of FSH alone or FSH + estradiol-17 beta (E2), either for 3 or 4 successive days of culture (model 1) or for 4 days of culture with medium change after 2 days of culture (model 2). The addition of FSH increased 125I-hCG specific binding in a dose-dependent manner to a maximum of approximately 110-fold (model 1) or 45-fold (model 2) compared with GC culture in medium alone. At the maximal effective dose of FSH, addition of E2 increased the 125I-hCG binding 2-fold (model 1) and 3.5-fold (model 2). 125I-hCG specific binding induced by FSH or FSH + E2 in model 1 was decreased by concurrent treatment (added on the day of cell inoculation) with porcine LFF (approximately 3-fold) or porcine serum (approximately 4.5-fold). In model 2, however, porcine LFF increased FSH-induced 125I-hCG specific binding 3-fold, provided LFF was added only after GC were primed with FSH alone for 2 days. When porcine serum was added instead of porcine LFF, only a permissive action was observed. These data may suggest that an initial GC differentiation is indispensible for obtaining the FF stimulatory effect on FSH-induced 125I-hCG specific binding in rat GC.

The ability of intraglandular colloid, the holocrine secretion of cells of the marginal half of the bovine pituitary intermediate lobe, to enhance or suppress the proliferation of immature thymic cells of CH3/6JH mice, 4 to 6 weeks of age, was studied. The mice were given subcutaneous injections of colloid for 3 consecutive days at a dose of 20 mg/kg body weight in 0.2 ml of saline. The analysis of propidium iodide stained thymic cell preparations by means of flow cytometry showed that there was a significant increase in the percentage of cells in the S phase (proliferative phase) of the cell cycle of mice injected with colloid (33%) compared with saline injected (15%) and non-injected controls (7%). These findings are the first to suggest that various combinations and concentrations of intraglandular colloid neuropeptides play a role in the immune system and shed light on additional functions of the intermediate lobe.

In a trial with 50 fattening pigs (20 kg initial body weight), the effect of untreated rapeseed meal (RSM) (148 mmol glucosinolates and aglucones per kg dry matter) on the thyroid was compared with RSM treated with Cu2+ (9.5 mmol glucosinolates and aglucones per kg dry matter) and soybean meal (SBM). The diets containing 8% RSM were supplemented with 0.0625-1.0 and the SBM diet (control) with 0.125 mg iodine kg-1 (I). In comparison with SBM fed control, RSM treatment with Cu2+ resulted in a complete normalization of feed intake and growth. Only untreated RSM without I supplementation depressed performance and resulted in symptoms of I deficiency, but the thyroid and liver weight were also increased and the serum T4 content was significantly reduced in animals which were given RSM not supplemented with I, but treated with Cu2+. In young pigs (4 weeks) a plateau of the serum T4 content was achieved from 0.5 mg I kg-1 of the RSM diet onwards. In contrast, when the concentration of goitrogens was reduced by the treatment with Cu2+, the serum T4 level was increased significantly in groups fed with 0.125 mg I kg-1 diet and more. In older pigs (15 weeks) neither the content of goitrogens nor the I dosage affected the serum T4 level. On the other hand, the I content in the thyroid was a good indicator of the different goitrogenicity of the diet in the case of a low I supply. The present investigations show that pig diets with RSM (greater than 10 mmol glucosinolates and aglucones kg-1) should contain at least 0.5 mg I kg-1, but 0.1 mg supplementary I per kg is sufficient in diets without or with a low content (less than 1 mmol glucosinolates and aglucones per kg-1) of antithyroid compounds.

Corpora lutea removed from ovarian of cycling pigs in early luteal phase (1-3 days) were used. After enzyme dispersion the luteal cells were suspended in medium M 199 supplemented with 10% of calf serum. Cultures were carried out in triplicate and incubated at 37 degrees C for 24 h. After that time the following hormones were added to the culture medium; 100 ng LH, or 100 ng PRL or 100 ng LH plus 100 ng PRL. The cells were incubated with hormone for 6, 12, 24 and 48 h. LH added to the medium resulted in the increase of progesterone secretion (P less than 0.05) only during 6 h incubation (140% of control progesterone). Stimulatory effect of PRL was observed only after 12 h incubation (300% of control progesterone; P less than 0.001). The addition of LH plus PRL decreased progesterone secretion after 6 h incubation (33.3% of control progesterone; P less than 0.05), a little stimulatory effect being observed after 24 h incubation (141% of control progesterone). This study confirmed the results obtained with monolayer cultures previously described. PRL appeared to be a luteotrophic hormone which is responsible for the increase of progesterone secretion by the early developing corpus luteum of pig. From these data it was concluded that luteal cells may require either LH or prolactin but not both at a time to sustain higher level of progesterone secretion.

The binding of 3,5,3'-L-triiodothyronine (T3) and thyroxine (T4) on liver nuclear receptors and the activity of malic enzyme and ornithine decarboxylase was examined in infantile rats aged in 1, 3, 7, 23, 29 days and in adult rats. No changes in the affinity constants (Ka) of nuclear receptors were observed for T3 or T4. The maximum binding capacity (MBC) estimated with the use of Scatchard plot analysis was unchanged for T3, the highest MBC for 125I-T4 being noted in rats aged 7 days. Malic enzyme activity in rat liver during the first three neonatal weeks was almost undetectable, but markedly increased on the 29th day. Ornithine decarboxylase activity was found to be significantly higher on the first day after birth as compared with that of the remaining age groups. The findings indicate that the thyroid hormone-nuclear receptor complex in rat liver does not seem to be sufficient for the induction of these enzymes in postnatal period of life.

Hormonal parameters (see below) were determined in 78 male acne patients of both sexes (mean age 21.2 +/- 3.8 years; (mean +/- S.D.) and compared with 63 controls (25.0 +/- 4.2 years). In a female group consisting of 60 patients acne (23.2 +/- 5.0 years) and 28 controls (26.1 +/- 5.7 years) of age, blood sampling was performed in the luteal phase of the menstrual cycle. Testosterone (T), dehydroepiandrosterone-sulfate (DHEAS), androstenedione (A), free testosterone (FT) and 17-hydroxy-progesterone (17-OHP) were determined by standard radioimmunoassay methods. In addition, sex hormone binding globulin (SHBG), follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), 17 beta-estradiol (E2) and cortisol (F) were evaluated. Moreover, the counts of acne lesions in the face were performed in 34 males and females patients in order to investigate possible correlations between hormones and acne lesions. The results in the male group revealed a significant elevation only for F but not for the other hormones. However, the female acne group significantly elevated levels of T, DHEA and F and a decrease of E became apparent. In addition, the correlation between both free and total T and acne lesions were found in the total of males and females. In the female group, free T and total A were found to correlate with acne lesions. The evaluation of these results indicates that androgens play a more important role in female than in male acne at the hormonal and at the peripheral level in skin. Another interesting finding was the significant increase of F in both male and female acne subjects, thus stressing the role of suprarenal involvement.

The effect of nonsteroid antiandrogen flutamide on 3H-testosterone (3H-T) metabolism in vitro was studied in Wistar male rat prostatic and hepatic homogenates. Flutamide was administered per os in a dose of 25 mg/kg daily for 3, 10 or 30 consecutive days. Following 30 days 5 alpha-dihydrotestosterone (DHT) formation in the prostate was reduced by 50%. In castrated animals antiandrogen abolished the recovering action of testosterone propionate (TP) on 5 alpha-reductase activity. When added to incubation medium flutamide proved ineffective, while hydroxyflutamide appeared to decrease DHT formation. The metabolic utilization of 3H-T in the liver of rats receiving flutamide for 30 days was found to be 3 times lower. The formation of DHT, androsterone, ethiocholanolone and androstenedione was substantially suppressed. In castrated rats, both treated and nontreated with TP, flutamide also inhibited the formation of steroid metabolites of 3H-T. Synergism to flutamide and TP action on androgen metabolism in the liver is suggested to be related to antiandrogen ability of interaction with an unusual estrogen-binding protein of rat liver. The decrease in DHT formation induced by flutamide may play a role in the mechanism of its therapeutic action in prostatic cancer patients.