Age and sex dependence of the effects of an aqueous extract of Physalis alkekengi fruits on rat hepatic glucose 6-P dehydrogenase activity

Intraperitoneal injections of an aqueous extract of winter cherry fruits (Physalis alkekengi) to new-born, weanling and adult female rats and to weanling and adult male rats had no effect on body weight, liver weight and liver cytosol protein content. The specific activities of hepatic glucose 6-P dehydrogenase (an estrogen induced protein) in rats of different age and sex groups in terms of mU/mg protein were: treated new-born females, 15.9 ± 0.5; control, 29.1 ± 0.6; treated weanling females, 14.9 ± 0.3; control, 24.8 ± 0.7; treated adult females, 25.7 ± 0.5; control, 26.1 ± 0.5; treated weanling males, 7.9 ± 0.2; control, 7.9 ± 0.1; treated adult males, 9.6 ± 0.4; and control, 9.7 ± 0.3. Treatment of new-born and weanling female rats with the extract resulted in 40–45% reduction in hepatic G6PD activity. However, treatment of adult females, and weanling and adult males produced no significant change in the activity of this enzyme. The data are discussed both in terms of the increase in the capacity of rodent liver to metabolize steroidal compounds with age and the presence of low levels of circulating estradiol necessary for enzyme induction in male rats.     

Sex difference in subunit composition of hepatic glutathione S-transferase in rats

The activities of hepatic cytosolic glutathione S-transferases (GSTs) towards 1,2-dichloro-4-nitrobenzene in male rats were higher than those in females, however, the enzyme activities towards 1-chloro-2,4-dinitrobenzene were not significantly different between the two sexes. SDS-PAGE analysis of GSTs purified from male and female rat hepatic cytosols by affinity column chromatography showed that there was a significant difference in the subunit composition between the two sexes. With regard to the several isozymes of GSTs in male and female rats, isozymes with basic and neutral/acidic isoelectric points were separated into seven molecular species by chromatofocusing. These sex differences in the quantitative proportions of GST isozymes were also confirmed by immunotitration using anti-GST-BL and -AC antibodies. On the other hand, glutathione peroxidase (GSH-Px) activities in rat hepatic cytosol towards hydrogen peroxide and cumene hydroperoxide were markedly higher in females than in males. Of the two types of GSH-Px, selenoenzyme (Se-GSH-Px) and the Se-independent enzyme (non-Se-GSH-Px), the former was found to be mainly responsible for the sex difference in the enzyme activities. Moreover, the GSH-Px activity of GSTs, non-Se-GSH-Px, was also higher in females than that in males. Since GST isozymes of the BL type are known to possess GSH-Px activity towards cumene hydroperoxide, the increased activities of non-Se-GSH-Px in the female hepatic cytosol seemed to be mainly due to the increased transferase activities of the isozymes, GST-L2 and -BL.     

Electrophoretic and immunochemical characterization of 3 alpha-hydroxysteroid/dihydrodiol dehydrogenases of rat tissues.

The properties of 3 alpha-hydroxysteroid/dihydrodiol dehydrogenase from Sprague-Dawley rat liver cytosol have been re-examined in light of several reports which suggest that multiple forms of the enzyme may exist in this tissue. During enzyme purification, chromatography on DE-52 cellulose and chromatofocusing columns indicated the existence of only one form of the protein. Re-chromatography of the purified enzyme by either of these techniques failed to resolve the protein into additional forms. When the purified enzyme was subjected to SDS/polyacrylamide-gel electrophoresis a single band corresponding to Mr 34,000 was detected. Two-dimensional gels showed one predominant protein with a pI of 5.9. Using the homogeneous enzyme as antigen, high-titre polyclonal antibody was raised in rabbits. Western-blot analysis of cytosolic proteins prepared from male and female Sprague-Dawley rat liver indicated the presence of a single immunoreactive band with an Mr of 34,000 in both sexes. All of the 3 alpha-hydroxysteroid dehydrogenase activity present in rat liver cytosol could be immunotitrated with the antibody and the resulting titration curve was superimposable on the titration curve obtained with the purified enzyme. Western-blot analysis of cytosolic proteins prepared from livers of male Wistar and Fischer rats also revealed the presence of a single immunoreactive protein with an Mr of 34,000. These data indicate that, contrary to previous reports, only one form of the dehydrogenase may exist in liver cytosols prepared from a variety of rat strains. Although 3 alpha-hydroxysteroid dehydrogenase activity is known to be widely distributed in male Sprague-Dawley rat tissues, Western blots indicate that only the liver, lung, testis and small intestine contain immunoreactive protein with an Mr of 34,000. The levels of immunoreactive protein in these tissues follow the distribution of dihydrodiol dehydrogenase.     

Regulation of hepatic malic enzyme by perfluorodecanoic acid

Perfluorodecanoic acid (PFDA) administration to adult male rats increased both the activity of hepatic malic enzyme and liver weight in a dose-dependent manner. Hepatomegaly and augmented activity of malic enzyme in liver were apparent within one day following PFDA administration and reached a plateau by three days posttreatment. Malic enzyme quantity per liver in PFDA-treated rats was elevated within one day following dosing and increased continually throughout five days posttreatment. Administration of PFDA to rats in the fed state also led to an increase in the specific activity of hepatic malic enzyme that peaked at three days following dosing. When compared to the fed condition, rats fasted for 48 hours had a decrease in both relative liver weight and the quantity of supernatant protein per liver. The total activity (U/liver) and specific activity of malic enzyme in the liver were also reduced in the fasted state. During the 24 hours after treatment in rats fasted for 48 hours, the body weight as well as the absolute and relative liver weight of animals receiving vehicle declined continuously in the absence of feed. Following the administration of PFDA to fasted rats, body weight was maintained until eight hours posttreatment but then declined at a rate similar to that found with the vehicle-treated group. Absolute and relative liver weight in PFDA-treated rats were increased significantly at eight hours posttreatment when compared to those receiving vehicle, and this increment was maintained throughout the rest of the 24 hours following dosing. While the activity and enzyme content of hepatic malic enzyme decreased in the vehicle-treated group, administration of PFDA to rats fasted for 48 hours prevented their decline. The specific activity of hepatic malic enzyme in 48 hours fasted rats receiving PFDA was also elevated significantly at 16 hours posttreatment. Thus, the administration of PFDA to the adult male rat in both the fed and fasted nutritional states was found to regulate hepatic malic enzyme by not only increasing enzyme quantity but also by augmenting the specific activity, (ie, catalytic state) of the enzyme.     

Purification of a fluoroacetate-specific defluorinase from mouse liver cytosol

Fluoraocetate-specific defluorinase, an enzyme which catalyzes the release of fluoride ion from the rodenticide fluoroacetate, has been purified 347-fold from mouse liver cytosol and shown to be distinct from multiple cationic and anionic glutathione S-transferase isozymes. Fluoroacetate-specific defluorinase was obtained at a final specific activity of 659 nmol of F-/min/mg of protein and was prepared in an overall yield of 12%. The isoelectric point of this hepatic enzyme was acidic, at pH 6.4, as determined by column chromatofocusing. The molecular weight of the active species was estimated at 41,000, and sodium dodecyl sulfate-polyacrylamide gels of the purified defluorinase demonstrated a predominant subunit, Mr = 27,000. Chromatofocusing completely partitioned the fluoroacetate-specific defluorinase from two separate peaks of murine anionic glutathione S-transferase activity. Rabbit antibodies prepared against the purified hepatic defluorinase quantitatively precipitated native defluorinase from mouse and rat liver, but were unable to immunoprecipitate cationic or anionic glutathione S-transferase enzymes from the same preparation. The evidence presented suggests that fluoroacetate-specific defluorinase and glutathione S-transferase activities are catalyzed by separate proteins present in the cytosol of mouse liver.     

Role of endogenous regucalcin in transgenic rats: suppression of kidney cortex cytosolic protein phosphatase activity and enhancement of heart muscle microsomal Ca2+-ATPase activity

Rats were generated by pronuclear injection of the transgene with a cDNA construct encoding rat regucalcin that is a regulatory protein of Ca2+ signaling. Transgenic (TG) founders were fertile, transmitted the transgene at the expected frequency, and bred to homozygote. Western analysis of the cytosol prepared from the tissue of TG female rats (5-week-old) showed a remarkable expression of regucalcin (3.3 kDa) protein in the liver, kidney cortex, heart, lung, stomach, brain, spleen, muscle, colon, and duodenum. Regucalcin expression of TG male rats was seen in the liver, kidney cortex, heart, and lung. In wild-type (wt) male and female rats, regucalcin was mainly present in the liver and kidney cortex. Regucalcin inhibited protein phosphatase activity in rat kidney cortex cytosol and activated Ca2+-ATPase activity in rat heart muscle microsomes. The suppressive effect of regucalcin on protein phosphatase activity was significantly enhanced in the cytosol of kidney cortex of TG male and female rats as compared with those of wt rats. Likewise, heart muscle microsomal Ca2+-ATPase activity was significantly enhanced in TG rats. The changes in their enzyme's activities in TG rats were completely abolished in the presence of anti-regucalcin monoclonal antibody (100 ng/ml) in the enzyme reaction mixture. Moreover, the body weight of TG female rats was significantly lowered as compared with that of wt rats. Serum inorganic phosphorus concentration was significantly increased in TG male and female rats, while serum calcium, glucose, triglyceride, free cholesterol, albumin, and urea nitrogen concentrations were not significantly altered in TG rats. Regucalcin TG rats should be a useful model to define a regulatory role of endogenous regucalcin in the tissues in vivo.     

Studies on tissue distribution of unusual estrogen-binding protein in rats with the help of immunoblotting

Tissue distribution in male and female rats of unusual immunoreactive material specific for the hepatic estrogen-binding protein (UEBP) was studied by means of immunoblotting analysis. From 28 organs and tissues studied only the liver of animals of both sexes was found to contain polypeptide with Mr, close to Mr of purified UEBP (approximately 31,000), which reacts with anti-UEBP specific antiserum. Detection of the immunoreactive material in female liver, which does not contain any hormone-binding activity of UEBP, suggests pre- or posttranslational modifications of the protein. It is concluded that the regulatory action of UEBP on steroid biodynamics bears a narrow-directed, organ-specific character.     

Identification of glutathione S-transferase as a substrate and glutathione as an inhibitor of in vitro calmodulin-stimulated protein methylation in rat liver cytosol

This report describes the isolation of the major calmodulin-stimulated methyl acceptor protein of adult rat liver cytosol. This Mr 29,000 methyl acceptor protein (MeAP29) has been purified to apparent homogeneity using ammonium sulfate precipitation and chromatography on DEAE-cellulose, phosphocellulose, hydroxylapatite and Sephadex G-75. Affinity chromatography on glutathione-Sepharose and assays of enzyme activity indicate that MeAP29 is a member of the glutathione S-transferase family. We further show that glutathione can act as an inhibitor of calmodulin-stimulated in vitro methylation of MeAP29 and that MeAP29 methylation is enhanced in non-dialyzed liver cytosol from rats with lowered glutathione levels.     

Glycerol-3-phosphate dehydrogenase expression and oxygen consumption in liver mitochondria of female and male rats with chronic alteration of thyroid status

In our chronic experiments (over several months), the activity and protein amount of glycerol-3-phosphate dehydrogenase (GPDH) in mitochondria isolated from the liver of adult male and female inbred Lewis strain euthyroid (EU), hyperthyroid (TH), and hypothyroid (HY) rats were analyzed by biochemical and Western blot methods. The TH status was induced by intraperitoneal injections of 3,3',5-triiodo- L-thyronine and the HY status with 0.05% solution of methimazole in drinking water. The TH status led to a significant increase and the HY status to a significant decrease of enzyme activity and protein amount in both male and female animals. These changes were, however, more pronounced in females. The EU and TH female rats also showed a significantly higher activity and the TH female rats showed also a significantly higher enzyme amount in comparison with males, while the HY rats showed low levels in both sexes. The glycerol-3-phosphate-dependent oxygen consumption of freshly isolated rat liver mitochondria from the TH animals was higher in comparison with the EU animals and it was activated by idebenone, a synthetic analogue of coenzyme Q, in both the EU and TH rats. Measurements of serum thyroid hormone levels and analysis of anatomical parameters (relative heart and thyroid gland weights) confirmed that our procedures inducing the TH and HY states are efficient and reliable and that determination of GPDH can serve as an additional criterion for the evaluation of the thyroid hormone status.     

Isoelectric focusing of glutathione S-transferases from rat liver and kidney

The glutathione S-transferases that were purified to homogeneity from liver cytosol have overlapping but distinct substrate specificities and different isoelectric points. This report explores the possibility of using preparative electrofocusing to compare the composition of the transferases in liver and kidney cytosol. Hepatic cytosol from adult male Sprague–Dawley rats was resolved by isoelectric focusing on Sephadex columns into five peaks of transferase activity, each with characteristic substrate specificity. The first four peaks of transferase activity (in order of decreasing basicity) are identified as transferases AA, B, A and C respectively, on the basis of substrate specificity, but the fifth peak (pI6.6) does not correspond to a previously described transferase. Isoelectric focusing of renal cytosol resolves only three major peaks of transferase activity, each with narrow substrate specificity. In the kidney, peak 1 (pI9.0) has most of the activity toward 1-chloro-2,4-dinitrobenzene, peak 2 (pI8.5) toward p-nitrobenzyl chloride, and peak 3 (pI7.0) toward trans-4-phenylbut-3-en-2-one. Renal transferase peak 1 (pI9.0) appears to correspond to transferase B on the basis of pI, substrate specificity and antigenicity. Kidney transferase peaks 2 (pI8.5) and 3 (pI7.0) do not correspond to previously described glutathione S-transferases, although kidney transferase peak 3 is similar to the transferase peak 5 from focused hepatic cytosol. Transferases A and C were not found in kidney cytosol, and transferase AA was detected in only one out of six replicates. Thus it is important to recognize the contribution of individual transferases to total transferase activity in that each transferase may be regulated independently.     

The estrogen receptor in the rat kidney. Ontogeny, properties and effects of gonadectomy on its concentration

Estrogens have been suggested as modulators of the conversion of 25-hydroxyvitamin D3 to dihydroxylated compounds in the kidney. In order to further explore this hypothesis the estrogen-binding components in the kidney were studied in adult and immature rats. The basal receptor levels in adult animals were 9.6 fmol/mg protein (female) and 21.9 (male). The receptor-ligand complex had a Kd of 0.7 nM. Furthermore, the kidney receptor displayed similar characteristics as those of the cytosol liver estrogen receptor in terms of sedimentation properties on sucrose gradients, isoelectric focusing and ligand binding specificity. The ontogeny of cytosol high affinity estrogen binding sites was elucidated in female and male animals. Detectable levels of receptors (5 fmol/mg protein) were found during the first postnatal week in both sexes. During days 22-25 receptors reached maximum concentrations at about 30 fmol/mg protein. In the male this level then remained relatively constant throughout the time of study (60 days), whereas in the female the concentration decreased gradually over a period of 12-15 days to a basal level of 10 fmol/mg protein. A temporal study on the short- and longterm effects of ovariectomy on the concentration of estrogen binding sites in the kidney cytosol was also carried out. Shortly after gonadectomy (2-12 h) no effect was detected. During 20-48 h after the operation a 75% increase in the receptor level was seen. The results indicate a multihormonal control of the estrogen binding protein in the kidney similar to that seen in the liver. Furthermore, the data suggest that estradiol down-regulate its own receptor. The results are discussed in relation to present concepts on the actions of estrogens and the metabolism of vitamin D3.     

The initial synthesis of proteins during development. Phosphoenolpyruvate carboxylase in rat liver at birth

1. A specific antibody, prepared by immunizing rabbits with phosphoenolpyruvate carboxylase (EC 4.1.1.32) purified from adult rat liver, was used to study the appearance of this enzyme in livers from developing rats. 2. Although some inactive precursor of the enzyme may be present in foetal liver, the amount is not sufficient to account for the enzyme appearance at birth. 3. The rate of phosphoenolpyruvate carboxylase synthesis relative to other cytosol proteins increases 20-fold from the foetus to the 1-day-old rat. The high rate of synthesis was maintained at least until 3 days after birth. 4. There was no measurable degradation of phosphoenolpyruvate carboxylase during the first day after birth. During this period the hepatic enzyme content increased 12-fold. 5. When phosphoenolpyruvate carboxylase attained a constant activity in the liver of rats 2 days after birth the half-time of degradation was approx. 13h. 6. We suggest that the pattern of changes occurring during appearance of phosphoenolpyruvate carboxylase is similar to substrate-induced enzyme induction in bacteria.     

Tissue kallikrein-binding protein is a serpin. I. Purification, characterization, and distribution in normotensive and spontaneously hypertensive rats

Kallikrein-binding protein was purified to apparent homogeneity from rat serum by Affi-Gel Blue, DEAE-Sepharose CL-6B, Sephacryl S-200 chromatography, and preparative gel electrophoresis or high performance liquid chromatography. The purified protein migrates as a single band of 60 kDa in a sodium dodecyl sulfate-polyacrylamide gel under reducing conditions. It is an acidic protein with isoelectric points ranging from 4.2 to 4.6. The amino terminus of the binding protein is an Asp residue as determined by sequence analysis. It forms a 92-kDa sodium dodecyl sulfatestable complex with kallikrein with a t1/2 of 18 min. Western blot and radioimmunoassay showed a distribution of the kallikrein-binding protein in serum, urine, and various tissues with a 5-10-fold lower amount in spontaneously hypertensive rats (SHR) than in Wistar-Kyoto rats (WKY). A full length cDNA clone encoding the kallikrein-binding protein was isolated from a rat liver cDNA library by immunoscreening and the translated amino acid sequence matches the amino-terminal 29-amino acid sequence of the binding protein. The cDNA sequence shares 68.8% identity with human alpha 1-antichymotrypsin and is identical to that of a rat hepatic protein. Dot blot analysis shows that kallikrein-binding protein is expressed at high levels in the liver and at low levels in the lung, salivary gland, and kidney. Its mRNA level in the liver decreases by 2-fold after acute phase inflammation and is higher in male than in female rats. Genomic Southern blot analyses reveal restriction fragment length polymorphisms between SHR and WKY rats in the binding protein locus. The results indicate that rat kallikrein-binding protein belongs to the serpin superfamily and its level is significantly reduced in the spontaneously hypertensive rats.     

Androgen receptor in rat liver: Hormonal and developmental regulation of the cytoplasmic receptor and its correlation with the androgen-dependent synthesis of α2u-globulin

The cytoplasmic receptor for 5α-dihydrotestosterone has been identified in the rat liver and partially characterized. The receptor is a protein with a sedimentation coefficient of 3.5 S and binds both androgens (5α-dihydrotestosterone and testosterone) and estradiol-17β with high affinity. At saturating concentration, for every mole of estradiol there seem to be three moles of 5α-dihydrotestosterone bound to the receptor. Whereas estradiol stronly inhibits the uptake of 5α-dihydrotestosterone by the receptor, the presence of 5α-dihydrotestosterone only weakly interferes with estradiol binding.The level of the androgen receptor activity in the hepatic cytosol was found to follow closely the level of the urinary output of α-_2u-globulin, an androgen-dependent protein of hepatic origin. Immature and senile male as well as female rats, which do not normally produce α_2u-globulin, also lacked androgen receptor activity in their hepatic cytosol. Castration of the adult male rats results in a gradual drop of the urinary output of α_2u-globulin as well as of the hepatic androgen receptor activity. Androgen treatment of immature and senile male rats does not induce α_2u-globulin or any receptor activity. Administration of estradiol to adult male rates results in complete inhibition of both α_2u-synthesis as well as complete loss of the cytosol androgen receptor activity in these animals. These results strongly indicate that the hepatic the hepatic androgen receptor activity. Androgen treatment of immature and senile male rats does not induce α_2u-globulin or any receptor activity. Administration of estradiol to adult male rats results in complete inhibition of boty α_2u-synthesis as well as complete loss of the cytosol androgen receptor activity in these animals. These results strongly indicate that the hepatic androgen receptor is an inducible protein whose synthesis is regulated by its own ligands, the androgens acting as the positive and the estradiol as the negative signals.     

Purification and immunochemical characterization of the cytoplasmic androgen-binding protein of rat liver

The cytoplasmic androgen-binding (CAB) protein of the male rat liver has been implicated to play a role in the androgen-dependent regulation of alpha 2u-globulin synthesis. The liver of the adult male rat contains about 50 fmol of specific high-affinity androgen-binding activity per milligram of total cytosolic protein. Photoaffinity labeling with [3H]R-1881 followed by SDS-polyacrylamide gel electrophoresis and autoradiography shows that the CAB is a 31-kilodalton protein. By means of DEAE-cellulose chromatography and preparative SDS-polyacrylamide gel electrophoresis, we have purified the CAB protein to electrophoretic homogeneity and have raised polyclonal rabbit antiserum that is monospecific to this protein. In the sucrose density gradient, the antiserum reacted with the androgen-binding component of the male liver cytosol prelabeled with tritiated dihydrotestosterone. Western blot analysis of the liver cytosol showed that the antiserum recognizes only the 31-kDa androgen-binding component. Such immunoblotting also showed that unlike the young adult, the androgen-insensitive states during prepuberty and senescence are associated with a marked reduction in the hepatic concentration of the immunoreactive CAB protein. No immuno-chemical cross-reactivity between CAB and another androgen-binding component of Mr 29K (which is associated with androgen insensitivity during prepuberty and senescence) was observed. The latter finding favors the possibility that 31- and 29-kDa androgen-binding components may have distinct sequence structure.     

Sex-linked changes in immunoreactive glucose-6-phosphate dehydrogenase in rat liver

The level of hepatic immunoreactive glucose-6-phosphate dehydrogenase protein was found to correlate well with the enzyme activity in adult rats fed the stock laboratory diet in a variety of hormonal conditions. The amount of immunoreactive protein and enzyme activity was 2-fold greater in sexually mature female rats compared with aged matched male animals. However, this difference was absent in diabetic animals, and furthermore although triiodothyronine administration to the diabetic male rat could restore the level of enzyme activity to that of the normoglycaemic animal, it was much less effective in the female animal. In contrast, administration of insulin to the normoglycaemic animal increased the level of glucose-6-phosphate dehydrogenase in the female, but was without effect in the male. These results are discussed in relation to the possible role of thyroid status and steroid sex hormones in the regulation of hepatic glucose-6-phosphate dehydrogenase.     

Intracellular enzymes of collagen biosynthesis in rat liver as a function of age and in hepatic injury induced by dimethylnitrosamine. Purification of rat prolyl hydroxylase and comparison of changes in prolyl hydroxylase activity with changes in immunoreactive prolyl hydroxylase.

Prolyl hydroxylase was purified from newborn rats by affinity chromatography using poly(L-proline), and antiserum to the enzyme was prepared in rabbits. The rat prolyl hydroxylase was similar to the chick and human enzymes with respect to specific activity, molecular weight and molecular weights of the polypeptide chains. The activity of prolyl hydroxylase and the content of immunoreactive enzyme were measured in rat liver as a function of age in experimental hepatic injury. Active prolyl hydroxylase comprised about 13.2% of the total immunoreactive protein in the liver of newborn rats and the value decreased to about 3.6% at the age of 420 days. This decrease was due to a decrease in the enzyme activity, whereas only minor changes were found in the content of the immunoreactive protein. In hepatic injury, a significant increase was found in the ratio of active enzyme to total immunoreactive protein, owing to an increase in the enzyme activity. The data indicate that prolyl hydroxylase activity in rat liver is controlled in part by a mechanism which does not involve changes in the content of the total immunoreactive protein.     

Bile salt sulfotransferase: alterations during maturation and non-inducibility during substrate ingestion

Development of the capacity for hepatic biotransformation of potentially toxic, endogenous compounds such as lithocholate may be dependent on induction by substrate or hormonal modulation. Our aim was to observe the ontogeny of hepatic sulfotransferase (ST) activity, a presumed detoxification pathway, and to determine the effect of substrate ingestion and cortisone administration on ST activity. Pregnant rats were fed a standard chow diet containing lithocholate; the maternal diet was continued during the suckling and weaning phase of the pups. Liver cytosol and serum were obtained from dams and from pups at weekly intervals from fetal life through 4 weeks of age. In controls, there was a progressive increase in hepatic ST activity from 6.2 +/- 2.9 pmol/mg protein per min, (mean +/- SEM) in fetal liver, 18.1 +/- 3.9 at 1 week, an 33.6 +/- 7.2 at 2 weeks to a peak of 56.4 +/- 11.8 at 3 weeks of age. In female rats older than 4 weeks of age, ST activity in hepatic cytosol was threefold higher than in males. There was a decline to adult levels (9.2 +/- 2.4 in males and 39.4 +/- 4.3 in females) at 56 days of life. Cortisone acetate administration had no effect on enzyme activity in pups except those 3 weeks old or older in which there was a precocious decrease in enzyme activity to adult levels. The administration of lithocholate caused a dose-related postnatal alteration of intrahepatic bile ducts manifest as cholangitis with ductular proliferation; hepatocytes were spared.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sex differences in spironolactone induction of rat intestinal and hepatic p-nitrophenol UDP-glucuronyltransferase

In the present study we analyzed the effect of spironolactone administration on hepatic and intestinal p-nitrophenol-UDP-glucuronyltransferase activity. We used microsomal preparations from male and female Wistar rats to establish whether or not this effect was sex dependent. Enzyme activity was measured in the presence of UDP-N-acetylglucosamine, a presumed physiological activator of the enzyme. Female but not male microsomes showed an increase in enzyme activity of both hepatic and intestinal tissue preparations in response to the inducer pretreatment. In addition, the inducer effect observed in female rats showed a tissue-related difference, since percent increase in the intestinal enzyme activity was greater than that in the liver (127 and 52%, respectively). These results suggest that factors regulating enzyme activity or mechanisms involved in the inducer effect of spironolactone could be different in the intestinal mucosa in comparison to the liver. A possible explanation of sex-related response to spironolactone administration was discussed.