Effect of sex hormones on plasma T-kininogen in the rat

The influence of sex hormones on rat plasma T-kininogen concentration was examined. The level of T-kininogen in the post-pubertal female rat is about 3-times that of the male animal. Female rats castrated as adults or 15 days after birth, had low T-kininogen concentrations, near those of male rats. In contrast, castration of mature or immature male animals induced no change in T-kininogen. Treatment of castrated female or male rats with 17 alpha-ethinylestradiol significantly increased the T-kininogen level, whereas administration of testosterone or progesterone had no effect. The influence of estrogen was specific for T-kininogen, since plasma HMW kininogen concentration was the same in male and female rats and was not affected by castration or sex hormone treatment. T-kininogen concentration was not significantly changed in pregnant rat between the 12th and the 20th day of pregnancy, but increased after parturition. It was high in the newborn rat at birth and then decreased similarly over the next 3 weeks in males and females. It continued to decrease in the males, reaching the level of the adult rat, but it increased in the female from 3-4 weeks of age and reached the adult level at about 6-8 weeks. These data indicate that natural estrogens have a physiological influence on the plasma level of T-kininogen in female rats whereas testosterone had no effect on either male or castrated female rats. HMW kininogen is not physiologically dependent on sex hormones.     

Reactions of hypothalamic ascorbic acid, serum ceruloplasmin and the adenohypophysis to oestradiol: inhibition by L-thyroxine

Four weeks' administration of oestradiol benzoate to male and female rats in doses of 1 mg twice a week leads to adenohypophyseal hyperplasia and to an increase in the thyroxine-binding capacity of the adenohypophyseal proteins in vitro. At the same time, serum polyphenol oxidase (ceruloplasmin) activity rises and the hypothalamic ascorbic acid concentration falls. The simultaneous administration of L-thyroxine (0.1 mg/rat/per day) or dried thyroid (but not D-thyroxine) significantly inhibits these changes (adenohypophysis, ceruloplasmin) or completely suppresses them (hypothalamic ascorbic acid). L-thyroxine evidently blocks the action of oestradiol in the adenohypophysis, the liver and the hypothalamus; the significance of this inhibition is discussed in relation to dopaminergic modulation of the adenohypophyseal reaction to oestradiol.     

The effect of 110mAg on ceruloplasmin oxidase activity in rats

The effect of single i.v. injection of 110mAgNO3 (0.183 mg Ag+ X kg-1 b.wt.) in rats on the ceruloplasmin oxidase activity (Cp) and copper serum concentration was studied. It was found that Cp activity in the serum decreased to 70% of the control value and simultaneously serum copper concentration decrease to 30% of the control level. In both cases the decrease was independent on the time elapsed after silver administration. Comparing these results with those reported recently in mice Cu deficit in the rat serum was approximately twice higher. This fact is considered to be an inter-species difference. The concentration of copper in the hepatic supernatant significantly decreased (to eight times from control value) after silver injection. Only less than 10% of the total amount of Ag found in whole liver was taken up to hepatic supernatant. GPC analysis of the supernatant (Sephadex G-75) revealed that no Ag-metallothionein fraction is present. On the basis of the results obtained it was concluded that the mechanism of silver inhibition of Cp oxidase activity remains still in question.     

Effect of tumor necrosis factor administration in vivo on lipoprotein lipase activity in various tissues of the rat

When added to murine adipocytes in culture, tumor necrosis factor (TNF) decreases the levels of lipoprotein lipase (LPL). Semb et al (1987. J. Biol Chem. 262: 8390-8394) have shown that administration of murine TNF to rats decreases lipoprotein lipase (LPL) in the epididymal fat pad with maximal inhibition requiring several hours. We have now tested the effects of treatment of rats with TNF on LPL activity in a variety of tissues and find that few show decreases in LPL under conditions that acutely increase serum triglycerides. Ninety minutes after treatment of male rats with human TNF (25 micrograms/200 g, i.v.), serum triglycerides rose 2.2-fold but there was no decrease in LPL activity in epididymal fat. Sixteen hours after TNF treatment LPL activity had decreased by 44% in epididymal fat, consistent with the previously reported data. In contrast, in female rats, no significant decrease was seen in LPL activity in parametrial adipose tissue at either 90 min or 16 hr after TNF administration despite increases in serum triglycerides (1.8-fold and 1.5-fold, respectively). There was little change in LPL activity in most other adipose tissue sites of male or female rats at either time after TNF treatment. No effect of TNF was seen on heart or diaphragm muscle LPL at any time. TNF treatment of both male and female rats produces consistent increases in de novo hepatic lipogenesis in vivo under conditions that increase serum triglycerides. It is unlikely that the limited effects of TNF on LPL in vivo can account for the rapid and sustained increase in serum triglycerides.     

Effect of oestrogen and ascorbic acid on the serum ceruloplasmin level in rats.

The administration of long-acting oestrogen (1 mg twice a week for 3 weeks) is followed, in rats, by an increase in the serum ceruloplasmin concentration to about 150% of the control value. The simultaneous administration of ascorbic acid in a dose of 10, 20 or 50 mg/rat/day in food raises the ceruloplasmin concentration to 180-200% of the control value (no significant difference was observed in the effect of the various doses of ascorbic acid). The increase produced by combining ascorbic acid with the oestrogen amounts to 20-30% of the value recorded in animals treated only with oestrogen. The mechanism by which ascorbic acid potentiates the effect of oestrogens on the ceruloplasmin level is not known.     

Hormonal regulation of rat renal cytochrome P450s by androgen and the pituitary.

The hormonal regulation of rat renal cytochrome P450s, P450 4A2 (K-5) and K-2, was investigated. The level of P450 4A2 in male rats was five times that in female rats and accounted for some 90% of total cytochrome P450, measured photometrically. Lauric acid omega- and (omega-1)-hydroxylation activities of renal microsomes of male rats were also higher than those of female rats. The sex differences in lauric acid hydroxylation activity seemed to arise from the differences in P450 4A2 concentrations, according to an immunochemical study. P450 K-2 was a female-dominant form in rat kidneys. The level of P450 K-2 in renal microsomes of male rats was one-tenth that of P450 4A2. Castration of male rats decreased the levels of P450 4A2 and treatment of castrated male rats with testosterone reversed the decrease. The castration of male rats decreased the lauric acid hydroxylation of the renal microsomes to the level of female rats. The administration of testosterone to castrated male rats reversed the decrease. Hypophysectomy of male rats decreased the level of P450 4A2 and the administration of growth hormone reversed the decrease when intermittent injections mimicking the male secretory pattern were given, although continuous administration mimicking the female secretory pattern did not. Castration of male rats did not affect the level of P450 K-2, but testosterone decreased its level. Hypophysectomy of male rats increased the level of P450 K-2 and growth hormone decreased its level in hypophysectomized rats. These results suggested that the expression of P450 4A2 was regulated by androgen or growth hormone and regulation of P450 4A2 was different from that of P450 K-2. To explore the regulation of renal cytochrome P450 further, testosterone was given to control (intact) or hypophysectomized adult female rats. P450 4A2 was induced in the kidneys of both control and hypophysectomized female rats to close to the level of male rats. Thus, P450 4A2 was directly regulated by testosterone as well as growth hormone, and the regulation of the male-dominant form in rat kidneys was different from that of the male-specific form in the rat liver, which is regulated mostly by growth hormone.     

Influence of gender on tamoxifen-induced biochemical changes in serum of rats

Tamoxifen, the widely prescribed drug in the prevention and therapy of breast cancer, may cause side effects which may be influenced by gender. The present study was undertaken to investigate the impact of gender on tamoxifen-induced toxic and biochemical changes following oral administration of tamoxifen at high dose level of 20 mg/kg once daily for a 2-week period in both male and female rats. The results showed marked increases in serum activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in female rats. In contrast, treatment with tamoxifen in male animals significantly decreased the activity of ALT, with a tendency for a decrease in serum AST levels. In female rats, a significant reduction in the serum activity of acid phosphatase (ACP) was noted, compared with a non-significant decrease in males. Non-significant changes in serum levels of alkaline phosphatase (ALP) were seen in both sexes. Tamoxifen lowered serum contents of total lipid and total cholesterol in both male and female rats. Serum levels of triglycerides were reduced in female rats as compared to a non-significant decrease in male animals. The serum albumin concentration was decreased in both male and female rats, while total protein was decreased only in female animals. Tamoxifen markedly increased serum levels of creatinine in female rats, compared with a non-significant rise in males. Total serum contents of calcium were similarly reduced in both males and females. This is the first study which points to gender-related differences in tamoxifen-induced toxic and metabolic changes in rats. The results indicated that females are more susceptible than males to tamoxifen toxicity, probably due to the ability of tamoxifen to antagonize the action of estrogen in females.     

Gender differences in myosin heavy chain-beta and phosphorylated phospholamban in diabetic rat hearts

The objective of this study was to determine whether a gender difference exists in myosin heavy chain (MHC) isoform or sarcoplasmic reticulum protein levels in diabetic rat hearts. As is the case with normal rodent hearts, all four chambers of the control rat hearts expressed almost 100% MHC-alpha. In 6-wk diabetic rats, MHC-beta expression in ventricles of males was significantly greater (78 +/- 7%) than in females (50 +/- 5%). The cardiac sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA2a) protein level was decreased and the phospholamban (PLB) protein level was increased in the left ventricle of diabetic rats, but there was no difference between male and female diabetic rats. The phosphorylated PLB level was decreased more in male than in female diabetic rats. Insulin treatment completely normalized blood glucose level, cardiac SERCA2a and PLB protein levels, and the decrease in MHC-beta levels in both male and female diabetic rats. Insulin treatment completely normalized serum insulin and almost completely normalized phosphorylation of PLB at serine 16 in male diabetic rats. Although insulin treatment completely normalized serum insulin levels in male diabetic rats, in females it only partially normalized serum insulin levels. Also, insulin treatment almost completely normalized phosphorylation of PLB at threonine 17 in female diabetic rats; however, the increase was significantly greater than that identified for insulin-treated male diabetic rats. We conclude that higher levels of MHC-beta and dephosphorylated PLB may contribute to more contractile dysfunction in male than in female diabetic rat hearts, and that phosphorylation of PLB at threonine 17 is more responsive to insulin in female diabetic rat hearts.     

Age-related changes in plasma proteins of analbuminemic rats

A mutant strain, Nagase analbuminemia rats (NAR), was established from Sprague-Dawley rats. Age-related changes in plasma proteins of NAR were investigated to obtain information of their abnormalities of protein metabolism. The total protein concentration in the serum of NAR of various ages was almost the same as that of normal rats of the same age. The albumin level of NAR was less than 0.05 mg/ml at all ages examined. The concentrations of serum alpha 1-antitrypsin, alpha-X protein, alpha 2-macroglobulin, transferrin, ceruloplasmin, IgG, IgA and IgM were higher in NAR than in normal rats except for the perinatal stage, but alpha 1-acid glycoprotein level in NAR was normal. The serum transferrin and ceruloplasmin levels were especially high in female adult NAR. The plasma fibrinogen concentration was also increased in NAR. These findings indicate that the normal total serum protein level of NAR was maintained by increase in the globulin concentration.     

Interaction of perphenazine and an ergoline derivative on oestrogen-induced adenohypophyseal growth.

Male and female rats were injected twice a week for three weeks with doses of 1 mg oestradiol benzoate (OE), were given perphenazine (P, 2 mg/rat/day) or the ergoline derivative D-6-methyl-8-ergoline-(I)-yl acetic acid amide (Deprenon SPOFA, D, 200 microng/rat/day) in their food or were treated with various combinations of all three factors. OE-induced adenohypophyseal growth was inhibited by D, but the inhibitory effect of D was completely suppressed by P. D also inhibited the OE-induced increase in the thyroxine-binding capacity of the adenohypophyseal proteins, but this inhibition was not suppressed by the simultaneous administration of P. The administration of OE was followed by elevation of the serum ceruloplasmin level, which was not inhibited by P or D, either alone or combined. Ovarian weight rose markedly after D and the increase was inhibited by the simultaneous administration of either OE or P.     

Estrogenic influence on the regulation of hepatic estrogen receptor-alpha and serum level of angiotensinogen in female rats

The majority of data regarding biological effects of estrogens is based on studies in male rats or ovariectomized (Ovx) female rats. Therefore, in this study, the effects of estradiol treatment on the regulation of the hepatic estrogen receptor and the level of circulating angiotensinogen were examined in the intact female rat. The data were compared with that of the hypophysectomized (Hx) rat. Animals were treated with either low (physiological) or high (pharmacological) doses of estrogen. In intact rats, the hepatic estrogen receptor (ER) level increased with increasing doses of estrogen. This was in contrast to the Hx rats where growth hormone (GH) and dexametasone (Dex) in combination were the sole modulators of the estrogen receptor. The angiotensinogen level increased in normal rats after estrogen administration in a dose dependent manner, regardless of the mode of administration. The pure antiestrogen ICI 182 780 efficiently blocked the increase in circulating angiotensinogen. The conclusion is that in the normal female, estrogens are important modulators of the serum angiotensinogen level.     

Sex-linked,androgen-dependent differences in renal retention of trimethylselenonium ions

The metabolism of trimethylselenonium ions (TMSe) was studied in male and female rats during maturation. Selenium (Se) retention in the whole body as well as in organs was found to be significantly higher in male rats than in female a few hours after parenteral administration of TMSe. The pronounced Se accumulation was observed in male kidneys. This sex-linked difference was dependent on the presence of gonades and started to be manifested with sexual maturation during the third decade of postnatal life. The effects of steroid hormones on the retention of Se from TMSe were examined in female and castrated male rats. The results indicate that TMSe metabolism in rat kidneys may be influenced by androgen steroids.     

Serum superoxide dismutase 3 (extracellular superoxide dismutase) activity is a sensitive indicator of Cu status in rats

Sensitivity of the assay for Cu,Zn superoxide dismutase 3 (SOD3), the predominant form of SOD in serum, can be increased, and interferences caused by low-molecular-weight substances in the serum can be reduced by conducting the assay at pH 10 with xanthine/xanthine oxidase and acetylated cytochrome c (cyt c) as superoxide generator and detector, respectively. Serum SOD3 activity was assayed under these conditions in an experiment where weanling, male rats were fed diets for 6 weeks containing 3, 5 and 15 mg Zn/kg with dietary Cu set at 0.3, 1.5 and 5 mg Cu/kg at each level of dietary Zn. Serum SOD3 responded to changes in dietary Cu but not to changes in dietary Zn. A second experiment compared serum SOD3 activity to traditional indices of Cu status in weanling, male and female rats after they were fed diets containing, nominally, 0, 1, 1.5, 2, 2.5, 3 and 6 mg Cu/kg for 6 weeks. Serum SOD3 activity was significantly lower (P < .05) in male rats fed diets containing 0 and 1 mg Cu/kg and female rats fed diet containing 0 mg Cu/kg compared with rats fed diet containing 6 mg Cu/kg. These changes were similar to changes in liver Cu concentrations, liver cyt c oxidase (CCO) activity and plasma ceruloplasmin in males and females. Serum SOD3 activity was also strongly, positively correlated with liver Cu concentrations over the entire range of dietary Cu concentrations (R(2) = .942 in males, R(2) = .884 in females, P < .0001). Plots of serum SOD3 activity, liver Cu concentration, liver CCO activity and ceruloplasmin as functions of kidney Cu concentration all had two linear segments that intersected at similar kidney Cu concentrations (18-22 microg/g dry kidney in males, 15-17 microg/g dry kidney in females). These findings indicate that serum SOD3 activity is a sensitive index of Cu status.     

Hyperresponsiveness of residual thyroid lobe of hemithyroidectomised rat to thyrotropin

The effects of hemithyroidectomy and thyrotropin administration on rat thyroid gland function were studied in adult male rats. Immediately after surgery or sham operation rats were treated daily with 0.12 IU of bovine thyrotropin (TSH) for 3 or 5 days. In control rats TSH dose applied resulted in an increase in serum T4 level at day 5 of experiment. Serum thyroxine concentration markedly decreased in sham operated and hemithyroidectomised rats, an effect observed at days 3 and 5 of experiment. TSH administration had no effect on serum T4 concentration in sham operated rats while in hemithyroidectomised animals such a treatment resulted in a marked increase in serum T4 level, a phenomenon observed in both time intervals studied. The reasons for hemithyroidectomy-induced hyperresponsiveness of rat thyroid residual lobe to thyrotropin are unknown.     

The time course of biochemical and histological changes following carbon tetrachloride-induced liver damage in rats of both sexes

A detailed analysis is presented of the time changes in the development of liver damage 6, 12, 24, 48 and 72 hours after i.p. administration of carbon tetrachloride [CCl4] in a dose of 0.75 ml, i.e. 1 200 mg/kg body weight to rats of both sexes. The severity of liver damage was assessed from the histological and biochemical changes of AST, ALT, alkaline phosphatase and GMT serum activity. From our experiments it follows that in male rats the level of transaminases increases earlier than in female rats, as early as 6 h after the administration of CCl4, reaching a maximum 12 h later. These changes prevail for a longer time period, the level of transaminases remaining increased even 72 h after CCl4 administration. In female rats the biochemical changes occur later reaching the maximum elevation of AST and ALT 24 h after CCl4 administration. The values slowly return to normal after 48 h, and after 72 h the levels of transaminases are identical with the control group. The above given biochemical results are in good agreement with the histological findings demonstrating a higher regenerative activity in female rats. This finding was also proved by specific liver DNA activity assay.     

Dissemination of carcinogenic H3-dialkylhydrazines in the neuro-endocrine system and their antigonadotropic effect in rats]

Three hours after the dimethylhydrazine-3H (DMH) treatment specific radioactivity in the male rat pituitary, adrenal cortex, and the testes was higher than in the liver by 53, 85, and 108%, respectively. Tritium incorporation into the hypothalamus was higher than that by the liver, cerebral cortex, and the brain stem by 33, 69, and 44%, respectively. Three hours after the diethyl-hydrazine-3H (DEH) treatment the specific activities of the pituitary and the testes in male rats were higher than that of the liver by 57 and 108%, respectively. A single DMH and DEH administration to male rats in a dose of 21 mg per kg body weight resulted in a significant decrease of the pituitary FSH level (by 63 and 53%, respectively). The data obtained were indicative of a marked influence of the carcinogenic dialkylhydrazines on the rat neuroendocrin system.     

大鼠运动病敏感性性别差异与血浆和垂体中AVP水平及垂体V1b受体表达水平的关系

目的：观察不同性别大鼠旋转前后不同时间点血浆和垂体精氨酸加压素（AVP）的含量以及垂体AvP—V1b受体阳性神经元数目和受体表达量,探讨AVP与运动病性别差异间的联系,为进一步认识运动病的发病机制提供实验依据。方法：采用条件性厌食症作为运动病模型。98只SD大鼠,雌雄各半,分别用放射免疫分析法、免疫组化及Western—blot法测定血浆、垂体AVP含量和垂体V1b受体表达水平。结果：旋转刺激后雌性大鼠糖精水（0．15％）饮用量的减少程度高于雄性大鼠。雌性大鼠血浆AVP含量在基础状态下高于雄性大鼠,旋转刺激后下降,而雄性大鼠无显著性变化。雌性大鼠垂体AVP含量在基础状态下也高于雄性大鼠,旋转刺激后8h下降。24h降低有显著性;雄性大鼠旋转后8h垂体AVP含量较旋转前明显下降,但降幅不及雌性大鼠,旋转后24h已近恢复。与应激反应密切相关的垂体V1b受体表达为阳性的神经元数目及V1b受体表达水平,在基础状态下,雌性大鼠显著高于雄性;旋转刺激后,雌性大鼠V1b受体表达为阳性的神经元数目和表达水平均明显降低,而雄性大鼠则无显著性改变。结论：运动病诱发刺激后,雌雄性大鼠血浆和垂体中AVP含量及垂体V1b受体表达均有差异,提示AVP的内分泌状态与运动病敏感性性别差异可能有某种关联。     

Characterization of serum, liver, and intestinal sialyltransferases from rats treated with colchicine

A modified high pressure liquid chromatographic method using lactose (Gal beta 1----4Glc) as an exogenous acceptor has been used to characterize the sialyltransferases known to increase in the serum of colchicine-treated rats. The results show a 10-fold increase of Gal beta 1----4GlcNAc alpha 2----6 sialyltransferase (alpha 2----6 ST), whereas the Gal beta 1----3GlcNAc alpha 2----3 sialyltransferase showed only 1.6-fold increase in the serum after 17 h of colchicine treatment. The sialyltransferase activity in serum using exogenous desialylated, alpha 1-acid glycoprotein as acceptor also showed an eightfold increase. In liver homogenate and Golgi membrane, the sialyltransferase activity when assayed with desialylated alpha 1-acid glycoprotein as acceptor showed a slight decrease after 4 h, but returned to normal level after 17 h. A similar trend was seen when the two transferases were assayed with lactose as acceptor. The antiserum to rat alpha 2----6 ST inhibited the sialyltransferase activity in serum, liver, and jejunal incubation medium. Jejunal sections from rats treated with colchicine for 4 h in presence of heated serum showed a decrease of sialyltransferase, with consequent increase of the alpha 2----6 ST enzyme activity in the medium. This result suggests that intestinal tissue could be a source of increased serum enzyme activity in colchicine treatment.     

Genetic polymorphism of ceruloplasmin in the rat

The genetic heterogeneity of ceruloplasmin in serum was studied in the progeny of the (LEW X BN)F1 X (LEW X BN)F1 rats. The results of the statistical analysis showed that the Hbb and c loci were linked. However, the autosomal Ces gene was not linked to the Hbb or c loci. The Ces gene was expressed in normal Mendelian pattern and had two alleles that manifested a low (Cesl) or high (Cesh) level of the enzyme in serum. The Cesl gene was expressed as a dominant in the F1 generation. Two phenotypes CES-H and CES-L were found in the F2 rats; the females in the parental strain and hybrid had higher ceruloplasmin concentration than the male rats.     

Evidence that triiodothyronine decreases rat serum leptin concentration by down-regulation of leptin gene expression in white adipose tissue

Conflicting results have been reported regarding the effect of triiodothyronine (T(3)) on serum leptin and adipose tissue leptin gene expression in human and animals. The aim of the present study was to evaluate the effect of administration of increasing doses of T(3) on serum leptin concentration and on leptin mRNA abundance in white adipose tissue of rats. The results presented in this paper indicate that administration of single different doses of T(3) to euthyroid rats resulted dose dependent increases of serum total T(3) concentrations which are associated with a decrease in white adipose tissue leptin mRNA level. The leptin mRNA level in white adipose tissue was negatively correlated with serum total T(3) concentration (r=-0.8, p<0.001). Like white adipose tissue leptin mRNA level, serum leptin concentration decreased after T(3) administration, and was also negatively correlated with the serum T(3) concentration (r=-0.8, p<0.001). In contrast, administration of T(3) to the same rats led to a significant increase in white adipose tissue expression of the malic enzyme gene (malic enzyme activity and malic enzyme mRNA level), a known target gene for T(3). The results indicate that T(3) exerts a selective inhibitory effect on white adipose tissue leptin gene expression in vivo. A conclusion is that T(3) decreases rat serum leptin concentration by down-regulation of leptin gene expression in white adipose tissue.