Overlapping effect of thyroid-stimulating hormone and follicle-stimulating hormone on the thyroid gland in baby chicken

Follicle-stimulating hormone (FSH) although quantitatively less effective than thyroid-stimulating hormone (TSH) in the thyroid gland, overlapped with the actions of the latter regarding the indices tested. Thus, it increased the follicular diameter and height of epithelial cells. These findings appear to support our earlier observation demonstrating an overlapping effect of tropic hormones in the gonads and suggest that the overlapping action of tropic hormones with related structure is a general phenomenon in the perinatal period.     

Specificity of the effect of growth hormone on DNA concentration in the nuclei of the lymphoid cells of hypophysectomized rats]

The effect of growth hormone on the DNA content in the nuclei of the thymus, spleen and the lymph node lymphocytes was studied by means of cytophotometry. In hypophysectomized rats the growth hormone increased the DNA content in the nuclei of the middle lymphocytes of these organs without altering its amount in the small lymphocytes. Thymus lymphocytes were the most sensitive to the hormone action. The DNA content in the nuclei of these cells increased as soon as one hour after the administration of the hormone; in 4 hours it reached the maximum. Other hormones with an anabolic effect (insulin, thyroxin, testosterone), induced no elevation of DNA in the thymocyte nuclei at that period of time. A conclusion was drawn on the high tropicity of the growth hormone to the cells of the lymphoid organs and particularly to the thymocytes (middle lymphocytes of the thymus).     

Influence of hormonal imprinting on hormone level. Permanent receptor damaging effect of pituitary hormones administered to newly-hatched cockerels

The overlapping effect of TSH and FSH on the gonad and on the thyroid gland can be demonstrated in cockerels even at the age of five weeks. These hormones influence the secretion of testosterone in a similar way and to a similar extent, while on the thyroxine level the influence of the specific hormone is more pronounced. Neonatal FSH and TSH treatment considerably decreased the basal testosterone level measured at the age of five weeks. Neonatal FSH treatment increased the basal T4 level while TSH treatment decreased it. The effect of TSH treatment administered at the age of five weeks in increasing the testosterone level was weakened after neonatal pretreatment with any iodine hormone. The effect of TSH treatment could only be inhibited by neonatal FSH pretreatment. Neonatal pretreatment with any of the trophormones caused a diminution of the T4 level augmenting of FSH and TSH administered at the age of five weeks.     

Influence of melatonin on rat thyroid, adrenals and testis secretion during the day.

The effect of pinealectomy and exogenous melatonin on circadian rhythm of triiodothyronine (T3), thyroxin (T4), corticosterone and testosterone in sham-operated and pinealectomized rats were investigated. The hormones concentration were RIA-measured and the circadian rhythm secretion were analysed by cosinor method. The findings suggest that pinealectomy abolishes the rhythmical character of corticosterone secretion and disturbs the circadian rhythm of T3, T4 and testosterone. Exogenous melatonin has the suppressive effect of diurnal secretion of T3, T4 and testosterone in pinealectomized rats but stimulates the rhythmical corticosterone secretion.     

Influence of pituitary hormones (hCG, TSH, Pr, GH) on testosterone level and on the functional activity of the Leydig cell in rat fetuses

One day after the cessation of treatment the Leydig cells of the fetuses of pregnant rats, treated between the 11th and 15th or the 16th and 20th days of gestation, reacted to pituitary hormones. This finding indicates that both the receptors and the postreceptor mechanisms were in operative state. The effect of the thyrotropic hormone (TSH) overlaps the effect of related gonadotropic hormone (hCG), although this effect becomes smaller from the 21st day. The parameters investigated - the spectrocyto-fluorimetrically measured RNA-DNA ratio and the plasma testosterone level - ran generally in parallel. Similarly to the above-mentioned hormones, prolactin also increased the testosterone level (though to lesser degree than hCG and TSH did), however, while it increased the RNA level but at the age of 16 days, it decreased it the age of 21 days. Somatotropin (GH) also increased somewhat the testosterone level; however, the effects of the two related hormones (Pr and GH) fell far beyond the effect of either TSH or hCG.     

Effects of aqueous extract of kola nut (cola nitida rubra) on reproductive hormones in rats

Our previous study suggests that aqueous extract of kola nut had effect on reproductive hormones in male rats. This study evaluates the effects of kola nut extract on plasma level of testosterone and luteinizing hormones in male rats. 30 adult male rats were used. These were divided into three groups: group A served as control and it received water only, group B and C received kola nut extract only (8mg/kg body weight), C served as recovery group. All the groups were treated for four weeks. The C which served as recovery group was allowed to recover for another four weeks at the end of the extract administration period. The plasma level of testosterone was significantly increased while that of luteinizing hormone was significantly decreased when compared with control animals. The recovery group showed values that were insignificantly lowered but a bit closer to those of the control animals. This showed that the rats were able to recover to some extent after the extract administration.Keywords: Kola nut, Testosterone, Luteinizing hormone, Rat.     

Can neonatal treatment with a related hormone adapt the receptor for itself?

Treatment of rats with endotoxin immediately after birth caused destruction of the cell membrane, resulting in depression of the thyroxin level and of the response to thyrotropin in adulthood. The thyroid gland of the rats treated neonatally with endotoxin failed to differentiate TSH from gonadotropin. Neonatal treatment (imprinting) with thyrotropin or gonadotropin after preexposure to the endotoxin improved the adult response to the exogenous hormone presented for imprinting after endotoxin. It appears that during the reconstruction stage following upon membrane perturbation in the critical period of receptor maturation, the adequate hormone or a related molecule can equally adapt the receptor for itself, but neither can fully compensate the perinatal membrane injury, nor the consequent diminution of receptor activity.     

Effect of thyroxine and prednisolone and the exogenous RNA induced by them on the proliferation of cells

As demonstrate experiments performed on cells of the primary culture of the newborn rat kidney, injection of thyroxin stimulates, and addition of prednisolone inhibits the proliferative activity of the cells in the culture. At a combined and simultaneous administration of these two hormones, as well as at injection of thyroxin 2 h before prednisolone, the thyroxin program, stimulating the cell proliferation is expressed. When thyroxin is administered 2 h after prednisolone, during first 12 h the prednisolone program is expressed, and then the proliferative activity of the culture returns to the initial level. At the cooperative action of oppositely directed factors for realization of the cell proliferative program, an essential role play the time factor and lag-period duration for each of the hormones interacting. Exogenic RNAs, obtained from the kidneys of the rats, to whom thyroxin or prednisolone have been injected, when they (RNAs) are injected into the culture, they produce effects, similar to those that are noted at injecting these hormones into the incubation medium. Thus, injection of the hormones to rats, results in formation, by the cells of the organ, induced RNAs, capable to transfer a hormonal signal and produce a hormone-like effect at regulation of the proliferative activity of the cell culture in the obtained exogenic RNA from the organ-donor.     

The effect of perinatal hormonal imprinting with 13-cis-retinoic acid (isotretinoin) on the thymic glucocorticoid receptors of female and testosterone level of male adult rats.

In earlier experiments, the long-term effect of perinatal treatment (hormonal imprinting) with all-trans-retinol and all-trans-retinoic acid on the thymic glucocorticoid and uterine estrogen receptors was studied and was found effective. In the present experiments, the imprinting effect of four retinoids (13-cis-retinaldehyde, 13-cis-retinoic acid, 9-cis-retinaldehyde and 9-cis-retinoic acid) was investigated, using receptor kinetic analysis and sexual hormone (testosterone and progesterone) level determinations. Exclusively 13-cis-retinoic acid (isotretinoin) had an effect, significantly decreasing glucocorticoid receptor affinity and increasing serum testosterone level. Relationships with RAR-RXR receptor binding and teratogenicity is discussed.     

Reactivity of the epithelial cells of the bovine oviduct in vitro on the exogenic gonadotropic and steroid hormones. Part I: The effect of gonadotropic and steroid hormones on the amount of lipids and activity of dehydrogenases.

Effects of 17 beta-estradiol, testosterone, progesterone, luteinizing hormone and a combined effect of estradiol and progesterone on the epithelial cells of the bovine oviduct cultured in vitro were investigated. It was found that these cells may transform under the effect of hormones. The effect of the applied hormones on the amount of lipids and activity of the dehydrogenases delta 5 3 beta-OH-SDH and G6P-DH was evident. Cells in vitro most intensely reacted on testosterone and estradiol: these hormones caused an increase of lipids and of enzymatic activity. The cells also reacted to progesterone and the luteinizing hormone which in turn decreased both activity and accumulation of lipids in cells.     

Infradian rhythms of the esophageal epithelium mitotic activity, corticosterone and thyroxin level in Japanese quail Coturnix japonica

Everyday dynamics of corticosterone and thyroxin levels on blood serum, as well as esophageal epithelium proliferation activity in Japanese quail males, have been investigated over a period of 16 days. It was estimated that different individuals synchronically exhibited a 4-day rhythm of the corticosterone serum level. The thyroxin level displayed a 3-day biorhythm. The mitotic index in the esophageal epithelium negatively correlated with the corticosterone level. The revealed infradian rhythms of the corticosterone and thyroxin levels, as well as esophageal epithelium mitotic index, should be taken into account while carrying out experiments concerning the determination of the hormone level and mitotic activity of epithelial tissues.     

Hormone epidermal growth factor interactions in development

Epidermal growth factor (EGF) is the most important member of a family of growth factors which exert their effects via a single 170,000 Mr plasma membrane receptor. Other members include transforming growth factor-alpha (TGF-alpha), amphiregulin and several viral growth factors. The receptor is widely distributed in fetal and postnatal tissues. The predominant family member in the fetus appears to be TGF-alpha. EGF production in tissues matures in the perinatal period. Activation of the receptor in the fetal and neonatal periods in rodents evokes important growth and development actions. Tissue EGF and EGF receptor concentrations are modulated by thyroid hormones, estrogen, testosterone and growth hormone, suggesting that selected growth and developmental actions of thyroid and steroid hormones may be mediated by EGF.     

Effect of the absence of neonatal testosterone imprinting on the activity of the microsomal enzyme system and on the dexamethasone binding of the thymus in adulthood

Healthy and neonatally castrated male rats were treated with testosterone twice perinatally, while other groups were treated with testosterone also in adulthood or received testosterone only in adulthood. Castration resulted in a moderate (but in some instances significant) decrease of PSMO (polysubstrate monooxygenase) level measured in adulthood. The decrease could partially be compensated by perinatal testosterone treatment. Further testosterone treatment administered in adulthood did not result in further alteration when compared either with the controls or with the neonatally treated animals. However, since in the controls the second testosterone treatment (following the neonatal one), had a decreasing effect, therefore the testosterone treatment administered in adulthood was responsible for the disappearance of the difference between the castrated animals and the controls treated both perinatally and in adulthood. On the basis of these findings it seems likely that the perinatal presence of testosterone plays a major role in the development of enzymatic imprinting and thus, in securing the capability of the liver to split testosterone in adulthood. Since testosterone influences the glycocorticoid receptors of the thymus (presumably by its overlapping effect), so the amount of free glycocorticoid receptors is always higher in the animals castrated neonatally than in the controls. Conversely, neonatal testosterone treatment somewhat increases the number of receptors detectable in adulthood.     

Influence of testosterone and/or luteinizing hormone releasing hormone analogue on precocious sexual development in the juvenile rainbow trout

The influence of testosterone, luteinizing hormone releasing hormone (LHRH) agonist and combinations of these hormones on gonadotropic hormone (GtH) levels in the sexually immature trout was investigated. Both the steroid and releasing hormone preparations, testosterone in Silastic capsules and cholesterol-pelleted LHRH-A, were formulated for sustained release and long-term biological action following a single hormone implantation. Marked increases in pituitary GtH followed testosterone and/or testosterone and LHRH analogue treatment combined, but the low pituitary GtH level in controls remained unchanged after LHRH analogue administration alone. Plasma GtH titers increased with time after testosterone treatment, indicating a positive steroid feedback effect by androgen on GtH in the juvenile rainbow trout. When combined with testosterone treatment, LHRH analogue augmented plasma GtH levels compared to fish receiving testosterone treatment alone. In males the elevated plasma GtH levels were associated with testes stimulation and onset of spermatogenesis; in females, however, no significant stimulation of the ovaries was observed. It can be concluded from these studies that the testosterone stimulus is sufficient to induce onset of sexual development in immature males but not females. Whereas LHRH analogue releases GtH from the testosterone-primed trout pituitary, LHRH treatment alone under these conditions fails to stimulate the juvenile trout reproductive system.     

Passage of testosterone,testosterone propionate and testosterone enanthate from silastic implants and the retention of testosterone once it enters the blood of ewes

Two studies were conducted to determine the passage of testosterone, testosterone propionate and testosterone enanthate through silastic implants and to determine the retention of the three hormones once they enter the blood. In the first experimental, ovariectomized ewes with implants containing testosterone propionate and ewes with implants containing testosterone enanthate had higher levels of plasma testosterone than ewes with implants containing testosterone. Testosterone enanthate implants released more hormone during the 13-day period than the testosterone propionate and testosterone implants and testosterone propionate implants released more hormone than testosterone implants. In the second experiment, concentrations of plasma testosterone were elevated longer for ovariectomized ewes intravenously administered testosterone propionate, than ewes receiving testosterone or testosterone enanthate intravenously.     

Investigation on the formation of the hormone reception mechanism

The formation of the hormone receptor mechanism is part of the embryonic development. The perinatal age seems to be critical for the maturation of this system, i.e. the development of the proper hormone selectivity, the number of the receptors, their sensitivity to the adequate hormone. Our team tried to get a closer view on this developmental period examining different parameters in different model systems. We were able to show that during the maturation of the hormonal system similar responses could be elicited by the later specific hormones or by the non-specific ones but structurally similar compounds. Also it became evident that one single hormonal treatment, applied during in the perinatal age, could influence the responsiveness to hormones of the adult animals.     

The effects of sex hormones on immune function: a meta‐analysis

The effects of sex hormones on immune function have received much attention, especially following the proposal of the immunocompetence handicap hypothesis. Many studies, both experimental and correlational, have been conducted to test the relationship between immune function and the sex hormones testosterone in males and oestrogen in females. However, the results are mixed. We conducted four cross‐species meta‐analyses to investigate the relationship between sex hormones and immune function: (i) the effect of testosterone manipulation on immune function in males, (ii) the correlation between circulating testosterone level and immune function in males, (iii) the effect of oestrogen manipulation on immune function in females, and (iv) the correlation between circulating oestrogen level and immune function in females. The results from the experimental studies showed that testosterone had a medium‐sized immunosuppressive effect on immune function. The effect of oestrogen, on the other hand, depended on the immune measure used. Oestrogen suppressed cell‐mediated immune function while reducing parasite loads. The overall correlation (meta‐analytic relationship) between circulating sex hormone level and immune function was not statistically significant for either testosterone or oestrogen despite the power of meta‐analysis. These results suggest that correlational studies have limited value for testing the effects of sex hormones on immune function. We found little evidence of publication bias in the four data sets using indirect tests. There was a weak and positive relationship between year of publication and effect size for experimental studies of testosterone that became non‐significant after we controlled for castration and immune measure, suggesting that the temporal trend was due to changes in these moderators over time. Graphical analyses suggest that the temporal trend was due to an increased use of cytokine measures across time. We found substantial heterogeneity in effect sizes, except in correlational studies of testosterone, even after we accounted for the relevant random and fixed factors. In conclusion, our results provide good evidence that testosterone suppresses immune function and that the effect of oestrogen varies depending on the immune measure used.     

Gonadal Steroids do not Affect Apolipoprotein E Expression in Aging Mouse Cerebral Cortex

The allelic variant of apolipoprotein (Apo) E4 is a known risk factor for the development of most common late onset form of Alzheimer’s disease (AD). As aging is associated with reduced circulating level of gonadal steroid hormones, hormone replacement therapies have been used for the possible treatment of AD. Both estrogen and testosterone have beneficial effects on brain due to interaction with apoE, but the underlying mechanism is still not clear. In this article, we report the effects of gonadectomy and hormone supplementation on apoE protein level in male and female mouse cerebral cortex during normal aging. We could not get any effect of gonadectomy and estradiol or testosterone treatment in adult and old mice of either sex. This suggests that during normal aging apoE protein level is not affected due to steroid hormone withdrawal or supplementation in the mouse cerebral cortex.     

Effects of sex hormone levels on aortic vascular reactivity and variables associated with the metabolic syndrome in sucrose-fed female rats

We studied the effect of varying levels of sex hormones, induced by ovariectomy and administration of testosterone or estradiol, on aortic reactivity in female rats with metabolic syndrome (MS) induced by a sucrose diet. Vasoreactivity of aortic rings, blood pressure, intra-abdominal fat, serum triglycerides, nitrates and nitrites, and TBARS were evaluated. Intact MS and ovariectomized MS had higher BP than intact control (C) and ovariectomized C, respectively; estradiol administration decreased BP in ovariectomized MS but not in ovariectomized C. Triglycerides and fat were both higher in MS. Triglycerides were not modified by surgery or hormone treatment, but ovariectomy increased fat. When ovariectomy was combined with hormones, however, fat was reduced to the level of intact rats. Ovariectomy decreased, but hormones increased, serum nitrates and nitrites. Vasoconstriction was larger in intact MS and ovariectomized MS + testosterone aortas than in intact C and ovariectomized C + testosterone, respectively. Vasodilation was reduced in intact MS and ovariectomized MS + testosterone compared with intact C, ovariectomized C + testosterone, ovariectomized MS, and ovariectomized MS + estradiol. The results suggest endothelial dysfunction in intact MS and ovariectomized MS + testosterone, but protection by ovariectomy + estradiol in MS due to hormones. Indomethacin reduced all contractions, but the effect was greater in estradiol-treated rats. L-NAME increased contractility, more in the ovariectomized C and MS groups and less in the estradiol-treated groups.