Effects of sex steroids and their inhibitors on endocrine parameters and gender growth differences in Eurasian perch (Perca fluviatilis) juveniles

Sex steroid inhibitors were used to characterize the effects of 17beta-estradiol (E2) and testosterone (T) on the sexual growth dimorphism of Eurasian perch juveniles. In experiment 1, growth responses to different doses of either E2 (25, 50, 75, and 100 mgkg(diet)-1) or fadrozole (Fa; 50 and 100 mgkg(diet)-1) were compared in triplicate tanks of 30 fish each during 85 days. In experiment 2, five diets containing (50 mgkg(diet)-1) Tamoxifen (Ta), Flutamide (Flu), Fa, E2, and T were tested in triplicate tanks of 20 fish each during 90 days. Steroid supplementation or inhibition increased or decreased E2 and T plasma levels. Moreover, E2 treatment induced a higher plasma vitellogenin level but decreased triidothyronine levels. Brain aromatase activity (AA) was lower in Fa-treated fish than in other groups. In experiment 1, E2 supplementation did not promote growth, but high doses had negative effects as did Fa. In experiment 2, a greater growth response was observed only in E2-treated females in relation to higher food intake (FI) not feeding efficiency. Fa also promoted growth and FI both in females and males during the last month of the experiment. Other treatments did not affect growth, but T treatment decreased FI in males. In conclusion, the results did not provide clear evidence for E2 action on sexual growth dimorphism, but showed that testosterone may decrease growth in males by decreasing food intake in Eurasian perch. Therefore, the acceleration of male-to-female growth differences with age may not be a result of promotion of growth in females by estrogens, but a consequence of a reduction in growth by increased secretion of androgens in males.     

Influences of gender and sex hormones on hypoxic ventilatory response in cats.

Hypoxic ventilatory response (HVR) is known to be increased by female as well as male sex hormones, but whether there are differences in HVR between men and women remains unclear. To determine whether gender differences exist in HVR, we undertook systematic comparisons of resting ventilation and HVR in awake male and female cats. Furthermore to explore the potential contribution of sex hormones to gender differences observed, we compared neutered and intact cats of both sexes. Resting ventilation differed among the four groups, but differences disappeared with correction for body weight. Intact females had a lower end-tidal PCO2 than intact male cats (females: 31.6 +/- 0.4 Torr vs. males: 33.6 +/- 0.4 Torr, P less than 0.05), indicating an increased alveolar ventilation per unit CO2 production. HVR expressed as the shape parameter A was similar among the four groups of animals. However, baseline (hyperoxic; end-tidal PO2 greater than 200 Torr) minute ventilation [VI(PO2 greater than 200)] differed among the groups. Therefore we normalized HVR by dividing the shape parameter A by VI(PO2 greater than 200) to compare the relative hypoxic chemosensitivity among the various groups of animals. In addition, we further normalized HVR for body weight, because body size influences ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of castration and sex steroids on sexually dimorphic development of the mouse submandibular gland

The aims of this study were to characterize sexual dimorphism in the submandibular glands of young adult mice and to determine how sex differences arise during postnatal development. In the mouse submandibular glands, prominent sexual dimorphism was observed at 30 days of age, when the male gland was superior in both the relative occupied area (ROA) and the mitotic rate of the granular convoluted tubules (GCT) to those of the female. By neonatal castration, this sexual dimorphism was abolished, and the intraglandular structures of castrated males were similar to those of normal females. In castrated mice of both sexes, daily treatment with testosterone and 5 alpha-dihydrotestosterone for 10 days from 20 days induced only the ROA of the GCT to increase to the normal male levels but not those of the other three regions of the glands, the acini, intercalated ducts and excretory striated ducts. Testosterone responsiveness of the glands, considering both the glandular weight gain and the mitotic rate of the GCT, was significantly higher in castrated males than in castrated females. On the other hand, 17 beta-estradiol had no effect on the glands of castrated mice. Therefore, the present study suggests that the testicular hormones are responsible for the masculine development of GCT of the glands, but not the ovarian hormones, and that there is a sex difference in the responsiveness of the glands to testosterone, which is more effective in males than in females.     

Male sex steroids are responsible for depressing macrophage immune function after trauma-hemorrhage

Recent studiessuggest beneficial effects of castration before soft tissue trauma andhemorrhagic shock on splenocyte immune functions. Nonetheless, itremains unknown whether this effect of testosterone depletion islimited to splenocytes or is a generalized effect on immune function.The present study was therefore carried out to determine whetherandrogen depletion before trauma-hemorrhage also has salutary effectson splenic and peritoneal macrophage as well as on Kupffer cellfunction, as indicated by interleukin (IL)-1 and IL-6 release. MaleC3H/HeN mice were castrated or sham-castrated 2 wk before theexperiment and were killed at 24 h after trauma-hemorrhage andresuscitation. Significant depression of macrophage IL-1 and IL-6release was only observed in sham-castrated mice, as opposed to normallevels of cytokine release from castrated animals after trauma-hemorrhage. In addition, only sham-castrated animals showed significantly increased levels of IL-6 release from Kupffer cells, which is believed to contribute to the systemic inflammatory response to trauma-hemorrhage. These observations suggest that the beneficial effects of androgen depletion before trauma-hemorrhage are not limitedto splenocyte immune functions but are more global in nature. Theseresults in surgically castrated animals suggest that androgen-blockingagents should be studied for their potential to reverse theimmunodepression associated with trauma-hemorrhage.

     

Interaction between sexual steroids and immune response in affecting oxidative status of birds

One hypothesis explaining the honesty of secondary sexual traits regulated by testosterone (T) is that T can impair the balance between pro-oxidant compounds and antioxidant defences, favouring a status of oxidative stress that only good quality individuals can sustain (oxidative handicap hypothesis). In the present study, we evaluated for the first time the effects of sexual steroids, T and its metabolites 5-α-dihydrotestosterone (DHT) and estradiol (E2) on oxidative damage and plasma non-enzymatic antioxidant capacity, while birds are faced by an oxidative challenge induced by an immune stimulation with sheep red blood cells. We used male and female diamond doves Geopelia cuneata, a species that shows an orange-red periorbital ring, whose size and color are strongly affected by androgens, but not by estrogens. Immunization increased oxidative damage in all groups, regardless of hormone treatment. It also decreased anti-oxidant capacity in all groups, except for testosterone treated birds. The ratio of oxidative damage over anti-oxidant capacity (oxidative stress) was increased in both immunological challenged controls and E2 birds, while challenged birds treated with androgens did not differ from non-challenged birds. The response of males and females to our treatments never differed. Our results undermine the idea that T can induce honest signalling through a pro-oxidant activity.     

Effects of chlordecone and malnutrition on immune response in rats

Effect of Chlordecone (Cd) and malnutrition on total body and spleen weights, and plaque forming cells (PFC) were studied. Rats were fed on normal, calcium (CaD), protein (PD) or Ca+P-deficient diets containing 0, 10 or 100 ppm of Cd for 2 or 4 weeks. High (95−100%) mortality was observed in malnourished rats treated with 100 ppm of Cd for 4 weeks. A slight decrease in body weight and an increase in spleen weight was observed in normal but not malnourished rats treated with 10 ppm of Cd for 4 weeks. PFC were significantly increased in both malnourished and Cd-treated rats. Similar increase in PFC was observed in rats fed on CaD but not PD diet containing 10 or 100 ppm of Cd. Whereas, rats fed on Ca+P-D diet containing 100 ppm of Cd exhibited a significant decrease in PFC.     

Effects of ventricularly implanted sex steroids on calling and locomotor activity in castrated male Japanese quail

To clarify the different actions of steroid hormones on calling and locomotor activity, minute pellets of steroid hormones were stereotaxically implanted into the third ventricle of castrated Japanese quail. Testosterone (T) pellets were effective in inducing calling to about 60% of that observed in castrated quail given subcutaneous implants of T. However, implants of 5 alpha-dihydrotestosterone (5 alpha-DHT) were completely ineffective and effectiveness of estradiol-17 beta (E2) was very slight, if any. On the other hand, E2 and T pellets enhanced locomotor activity; E2 was more potent than T, whereas 5 alpha-DHT was again ineffective. Cholesterol pellets had no effects on either behavior. Daily rhythms of calling and locomotor activity were also found in birds given ventricular T implants. These results indicate that T but not E2 is required for induction of calling and that aromatization occurs in the brain to exert enhanced locomotor activity. The results also indicate that changes in circulating T do not influence daily rhythms of calling and locomotor activity.     

Severe hypoxemia in the absence of blood loss causes a gender dimorphic immune response

A gender dimorphic immune response has beenobserved after trauma and severe hemorrhage, a condition believed to beassociated with tissue hypoxia. Although studies have shown thathypoxemia per se in males causes a systemic inflammatory response, itis unclear if the inflammatory response to hypoxemia exhibits gender dimorphic characteristics. To study this, male and female C3H/HeN micein the proestrus state of the estrous cycle were subjected to hypoxemia(95% N₂-5% O₂) or sham hypoxemia (room air)for 60 min. Later (2 h), plasma interleukin (IL)-6 and tumor necrosis factor (TNF)- levels were determined along with splenic immune responses. Plasma IL-6 and TNF- concentrations after hypoxemia weresignificantly increased in males but not in females. Splenocyte proliferation was depressed in males after hypoxemia but not in females. A shift toward an immunosuppressive Th-2 cytokine profile wasobserved in males after hypoxemia [decreased interferon- (Th-1) andincreased IL-10 (Th-2)], whereas no such shift was observed infemales. Splenic macrophage IL-6, IL-10, and IL-12 production weresuppressed in males after hypoxemia; however, such suppression was notobserved in females. These findings therefore indicate that a genderdimorphic immune response also exists after hypoxemia in the absence ofblood loss and tissue trauma, similar to trauma-hemorrhage.Furthermore, because no systemic inflammatory response or alterationsin T lymphocyte or macrophage functions are observed in proestrusfemales but such parameters are markedly altered after severe hypoxemiain males, these studies indicate that proestrus females can toleratehypoxemia better than males.

     

Radioautography of tritiated sex steroids in the rat

Summary Four radioautographic methods for soluble substances were compared to each other. When using the wire-loop method of Miller et al. (1964) difficulties were met because detachment of emulsion from the object slide. Severe chemographic artifacts in the radioautograms hampered the results when using the method of Appleton (1964). The freeze-drying and paraffin embedding method of Hammarström et al. (1965) resulted an extensive diffusion of radioactivity. Therefore, a simple dry-fixation method for steroid radioautography was developed.Among the female hypothalamic nuclei the preoptic area, the anterior hypothalamic area, the nucleus ventromedialis, paraventricularis and arcuatus showed the highest labelling index after injection of tritiated estradiol intravenously. In addition, high labelling index was seen in the hippocampus. Almost all radioactivity was seen in the nuclei of the neurons. Radioactivity in the uterus was localized in the nuclei of the epithelial and stromal cells. Estradiol in the male rats localized in the nucleus paraventricularis, ventromedialis, dorsomedialis and amygdalae. Only very few of the prostatic cells were labelled.Tritiated testosterone was localized in both sexes in the hippocampus, in the nucleus arcuatus and ventromedialis. Some radioactivity was seen in the anterior hypothalmic area. The nuclei of the epithelial and stromal cells in the accessory sex organs (ventral prostate, seminal vesicle, epididymis) concentrated radioactivity very effectively.Tritiated dihydrotestosterone was localized in the epithelial and stromal cells of male accessory sex glands as testosterone.     

Effects of T-cell-mediated immune response on avian oxidative stress

We evaluated the oxidative cost paid by birds when coping with an immune challenge. We used the phytohaemagglutinin skin test (PHA) to assess the effects of the T-cell-mediated immune response on the concentration of reactive oxygen metabolites (ROMs), total antioxidant barrier (OXY) and total serum carotenoid concentration in wild nestlings of the Eurasian kestrel (Falco tinnunculus). Immunostimulation caused increased levels of ROMs, decreased OXY and increased circulating levels of carotenoids. These results suggest that an immune challenge can increase avian oxidative stress, and that carotenoids were remobilised from other tissues likely because their circulating levels were not sufficiently high to sustain an effective immune response.     

Effects of amphetamine on T-cell immune response in mice

Mice chronically injected with amphetamine (0.4 mg/kg/day) showed a reduction in thymus and spleen cellularity, and in peripheral T lymphocyte population. The blastogenic response of spleen lymphoid cells was assessed and amphetamine was found to inhibit T-cell proliferation. Amphetamine also reduced the capacity of mice to the development and passive transfer of immunity to Listeria monocytogenes.     

No effect of sex steroids on compensatory muscle hypertrophy

We studied the effects of sex steroids on muscle weight and oxidative capacity of rat plantaris muscles subjected to functional overload by removal of synergistic muscles. Eight weeks after bilateral synergist removal, plantaris muscles were strikingly hypertrophic compared with unoperated controls. After this period, there were selective alterations in the ability of the muscles to oxidize three substrates of oxidative metabolism. Thus 14CO2 production from [6-14C]glucose and [2-14C]pyruvate was significantly reduced, whereas there was no alteration in 14CO2 production from beta-[3-14C]hydroxybutyrate. Succinate dehydrogenase specific activity was decreased in overloaded muscle. There was no effect of sex hormone status on any of these parameters. Finally, 30 days of functional overload did not influence cytosolic androgen receptor binding. These results are not consistent with the idea that sex steroids and functional overload act synergistically.     

Effect of endogenous and synthetic sex steroids on the clearance of antibody-coated cells

Steroid hormones may influence the clinical expression of immunologic disease; however, their mechanism of action is uncertain. By using an experimental model, we studied the effect of sex steroids on the clearance of antibody-coated cells by macrophages in the spleen and liver. Progesterone significantly inhibited the clearance of IgG-coated E by splenic macrophages, whereas no effect was observed on the clearance of heat-altered E. This effect of progesterone was observed at serum concentrations which are attained during human pregnancy and the menstrual cycle. Furthermore, when splenic macrophages were isolated from progesterone-treated animals, they expressed decreased Fc gamma R activity. In addition, structural analogs of progesterone which have diminished glucocorticoid and progesterone activity retained this effect on macrophage Fc gamma R. In contrast, the estrogens estradiol and estriol as well as a structural estrogen analog with minimal estrogenic activity, 1,3,5(10)-estratrien-3,16 beta-diol, enhanced splenic macrophage Fc gamma R-dependent clearance. This action of estradiol could be partially inhibited by the antiestrogen tamoxifen. However, estradiol did not affect the C3-dependent clearance of IgM-coated E by hepatic macrophages. Concurrent administration of estradiol and progesterone demonstrated that the action of estradiol was predominant. These studies indicate that sex steroids alter splenic macrophage Fc gamma R function in vivo. This result may explain the alteration of disease activity in some human immunologic disorders during changes in hormonal state. Furthermore, analogs of progesterone and estrogen, as well as antiestrogens, which minimally affect the sex organs, retain the ability to alter splenic macrophage Fc gamma R function.     

Effects of sewage-water contamination on the immune response of a desert bat

Environmental pollutants may negatively affect the immune system of animals. Yet, this phenomenon has not been studied thoroughly in terrestrial animals that use polluted water for drinking and/or foraging. We experimentally tested the hypothesis that exposure to sewage water would affect the activation of the immune response in the bat Pipistrellus kuhlii that drinks from bodies of open water. We selected two water sources where bats forage in the Negev desert, Israel: natural springs and a sewage-polluted man-made reservoir. We captured 13 non-reproductive female bats in the vicinity of the natural springs and offered seven of them water from the sewage-polluted source for 30 days (treatment) and the remaining six bats were offered water from the natural spring (control). Consumption of contaminated water did not alter the bactericidal ability of blood plasma or the proportions of monocytes circulating in the blood. However, our data provided evidence that the 30-day treatment can cause a decrease in the relative levels of neutrophils and an increase in the levels of lymphocytes. Our study provides a first account for the effect of sewage pollution on bat immune response which may be important in desert environments, where water sources are scarce. We suggest hypotheses for future, more focused studies.