CA-treated Rats Research Articles

Effects of Centella asiatica Administration on NT-3 and CDKN2A Levels in Adult Rat Brains

Aims: This study aims to determine at the effect of Centella asiatica L. (CA) on Neurotrophin-3 (NT-3) brain level and Cyclin-dependent kinase inhibitor 2A (CDKN2A) brain level of rats aged 12, 24 and 36 weeks.
 Study Design: Experimental studies used rats aged 12, 24, and 36 months which were treated with CA extract 300 mg/BW was administered orally for 29 days in a row as described in previous study. In addition, untreated rats aged 12, 24, and 36 months were used as negative controls.
 Place and Duration of Study: Department of Biochemistry and Biology Molecular, Faculty of Medicine, Universitas Indonesia.
 Methodology: NT-3 and CDKN2A brain levels were measured using the ELISA method.
 Results: The results showed a significant decrease in NT-3 levels in rats aged 36 weeks that were given CA compared to control rats (Sidak multiple comparison test; P = .0493). In addition, the CDKN2A levels of CA-treated rats aged 36 weeks that were compared to control rats (Sidak multiple comparison test, P = .0041).
 Conclusion: This study proved that giving CA 300mg/kgBW for 29 days in adult rats aged 36 weeks has not been able to prevent aging in terms of NT-3 and CDKN2A proteins.

High Sensitivity to Cholic Acid-induced Colonic Tumorigenesis Makes Female PIRC Rats (F344/NTac-Apcam1137) a Suitable Model for Studying CRC-promoting Agents.

Rats of the adenomatous polyposis coli (Apc)-mutated female polyposis in rat (PIRC) (F344/NTac-Apcam1137) model exhibit a low level of intestinal tumorigenesis and are thus potentially exploitable as a model for identifying substances increasing colorectal cancer (CRC). To test this possibility, we treated such rats with the bile acid (BA) cholic acid (CA) (0.3% w/w in the diet), known to promote CRC, and assessed tumorigenesis. Precancerous colonic lesions (mucin-depleted foci) and intestinal tumors were dramatically increased in CA-treated rats compared to controls (p<0.01). Colon mucosa proliferation was higher and apoptosis lower than those in controls. Expression of nuclear receptor 1h4 (Nr1h4) gene [encoding for BA receptor farnesoid X receptor (FXR)], organic solute transporter beta (Ostb) and fatty acid-binding protein 6 (Fabp6), FXR-dependent BA transporters, were dramatically down-regulated in CA-treated rats. CA-increased tumorigenesis in female PIRC rats, with mechanisms involving increased proliferation, reduced apoptosis and marked down-regulation of genes controlling BA homeostasis. Since BAs have been implicated in CRC, we suggest that female PIRC rats can be used to identify CRC-promoting agents.

The effects of clavulanic acid and amoxicillin on cue-primed reinstatement of cocaine seeking.

Research using the cocaine self-administration and reinstatement animal model of relapse finds that the beta-lactam antibiotic, ceftriaxone, attenuates cocaine-primed reinstatement of cocaine seeking and upregulates two proteins that regulate glutamate release and reuptake (xCT and GLT-1, respectively) in the nucleus accumbens core (NAc). We tested three compounds with beta-lactam rings for their ability to attenuate cue-primed reinstatement and increase GLT-1 and xCT expression in the NAc and prefrontal cortex (PFC). Rats self-administered intravenous cocaine for 1 hr/day for 7 days then 6 hrs/day for 10 days. Cue-primed reinstatement tests began after 8-9 days of extinction training. Rats received oral vehicle, clavulanic acid (CA), amoxicillin (AMX), or CA + AMX (Augmentin; AUG) for 5 days prior to testing. Only AMX-treated rats demonstrated a reduction of cocaine-seeking that trended toward significance, warranting future investigation of a wider range of doses. In the NAc, GLT-1a expression was reduced in vehicle-treated rats relative to cocaine-naïve controls and was not restored by AMX or AUG. CA-treated rats reinstated more than vehicle-treated rats and exhibited GLT-1a and xCT expression intermediate between cocaine-naïve controls and vehicle-treated cocaine rats. In agreement with our previous work, cocaine did not decrease PFC GLT-1a expression. Cocaine reduced xCT expression in the PFC that was unchanged by any of the three compounds. These results indicate that AMX may be another beta-lactam that attenuates cocaine relapse. Furthermore, the upregulation of both GLT-1 and xCT in the NAc may be needed to attenuate cocaine seeking. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Effects of Centella asiatica on skeletal muscle structure and key enzymes of glucose and glycogen metabolism in type 2 diabetic rats

BackgroundDysregulation of glucose and glycogen metabolism are crucial mechanisms implicated in type 2 diabetes mellitus (T2DM). Centella asiatica (L.) Urban (Apiaceae) has been utilized as a traditional medicine in Africa and Asia for centuries and is commercially available as a dietary supplement. AimWe explored for the first time, the possible efficacy of Centella asiatica (CA) extract in ameliorating T2DM-induced changes in key enzymes involved in glucose and glycogen metabolism in the rat skeletal muscle. MethodsDiabetic rats were orally treated with vehicle, CA (500 and 1000 mg/kg) or metformin (300 mg/kg) daily for 14 days. Skeletal muscle activities of hexokinase (HK), phosphofructokinase (PFK) and fructose 1,6-bisphosphatase (FBPase) were determined by spectrophotometric assays while those of glycogen synthase (GS) and glycogen phosphorylase (GP) were assayed radio-chemically. Histological examination of skeletal muscle was also performed. ResultsRats with induced T2DM had reduced activities of HK (25%), PFK (88%), and GS (38%) when compared to non-diabetic rats. Treatment of diabetic rats with CA500 increased the activities of PFK (7-fold), and FBPase (23%). Further, treatment of diabetic rats with CA1000 also increased the activities of GS (27%) and GP (50%) with little change in these parameters for diabetic rats treated with CA500. These effects probably led to the reduced blood glucose level and elevated skeletal muscle glycogen content observed in CA-treated rats relative to diabetic controls. Furthermore, CA treated rats had reduced the morphological damage of skeletal muscle fibres compared to the non-treated diabetic control rats. ConclusionOur findings strongly suggest that the anti-diabetic effects of CA in part target muscle glucose and glycogen metabolism and hence supporting its folkloric medical use as an anti-diabetic remedy.

Amelioration of inflammatory responses by Socheongryong-Tang, a traditional herbal medicine, in RAW 264.7cells and rats.

Socheongryong-Tang (SCRT) is a natural medicine prescription that has been mainly used in East Asia for the treatment of inflammatory disorders, including asthma and allergic rhinitis. The present study evaluated the anti-inflammatory effects of SCRT on lipopolysaccharide (LPS)-stimulated RAW 264.7 cells and in a rat model of carrageenan (CA)-induced paw edema. Levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6 and prostaglandin E2 (PGE2) in the culture supernatant were quantified and nitric oxide (NO) production was monitored. In addition, the effect of SCRT on the protein expression of nuclear factor-κB (NF-κB), mitogen-activated protein kinases (MAPKs), inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) was assessed by western blot analysis. Furthermore, the effects of SCRT on acute inflammation in vivo and changes in the histomorphometry and histopathology of paw skin were observed using CA-treated rats. SCRT (1 mg/ml) inhibited the LPS-induced changes in the protein expression of NF-κB, JNK, ERK1/2, iNOS and COX-2, as well as the production of NO, PGE2 and cytokines. In the rat paw edema assay, administration of 1 g/kg of lyophilized powder obtained from the aqueous extracts of SCRT for 3 consecutive days inhibited the CA-induced increases in skin thickness, mast cell degranulation, and infiltration of inflammatory cells in the ventral and dorsal pedis skin within 4 h. These results demonstrated that SCRT exerts its anti-inflammatory activities in LPS-stimulated RAW 264.7 cells through decreasing the production of inflammatory mediators, including PGE2, NO and cytokines, via suppression of the NF-κB and JNK and ERK1/2 signaling pathways. In addition, the data of the CA-induced paw edema indicated an anti-edema effect of SCRT. SCRT (1 g/kg) reduced acute edematous inflammation through inhibition of mast cell degranulation and infiltration of inflammatory cells. Therefore, the present study provided scientific evidence for the anti-inflammatory activities of SCRT as well as the underlying mechanisms.

Local and Systemic Profiles of Inflammatory Cytokines in Carrageenan-induced Paw Inflammation in Rats

ABSTRACTObjective: Carrageenan (CA)-induced edema has been described as highly reproducible model of acute inflammation. However, little is known about the cytokines attributed to the CA-induced inflammation. In this study, we aimed to investigate the local and systemic expression profiles of various inflammatory cytokines following the subplantar injection of CA in rats.Methodology: Acute inflammation was induced in male Wistar rats by subplantar injection of CA. Serum and paw tissue were examined for the level of 19 specific inflammatory cytokines using antibody array. Further, the CA-elicited level of key inflammatory cytokines, cytokine-induced neutrophil chemoattractant (CINC)-2, CINC-3, interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, were quantified by enzyme-linked immunosorbent assay (ELISA).Results: Edema was peaked 3 h postinjection of CA in hind paw. Among 19 specific cytokines profiled using antibody array, CA significantly (p < 0.05) elicited the levels of CINC-2, CINC-3, IL-1β, IL-6, β-NGF, TNF-α, and VEGF in paw tissue and that of CINC-2 and CINC-3 in serum. Consistently, levels of CINC-2, CINC-3, IL-1β, IL-6, and TNF-α in tissue and CINC-2 and CINC-3 in serum were upregulated in CA-treated rats when compared to control, quantified by ELISA.Conclusions: This study corroborates the distinct pattern of inflammatory cytokines involved during CA-induced acute inflammation. Furthermore, data provide new evidence on elevated expression of rat CXC chemokines: CINC-2 and CINC-3 at the site of inflammation as well as their significant reflection in the circulation, thereby suggesting their frontline role in CA-induced acute inflammation.

Comparison of the hemostatic effects of oxidized cellulose and calcium alginate in an experimental animal model of hepatic parenchymal bleeding.

Background:Despite all recent developments, bleeding is still one of the main causes of increasing morbidity and mortality following both trauma and elective hepatic surgery. The main goal of treatment is stop the bleeding immediately. In this study, the hemostatic and histopathological effects of Ankaferd blood stopper (ABS), oxidized cellulose (OC), and calcium alginate (CA) were compared in an experimental liver injury.Materials and Methods:Forty Wistar albino rats were randomly divided into four groups of ten animals each, receiving 0.9% NaCl, CA, OC, or ABS following liver resection. After 5 days, the samples from the resection site were acquired for histopathological evaluation. The efficacy of the agents was assessed using the hematocrit level and histopathological examination. Statistical analyses were applied.Results:The amount of bleeding was lowest in ABS–treated rats, followed by those treated with OC, CA, and NaCl, respectively. The difference among the groups was statistically significant (P < 0.001). ABS–treated rats also had significantly less necrosis than those receiving OC; other differences in this regard were not significant. Inflammatory status was significantly different between OC- and CA–treated rats (P < 0.05) but not among the other groups (P > 0.05). No significant difference was determined between the groups regarding granulation (P > 0.05).Conclusion:ABS reduced the volume of bleeding in liver surgery and partial liver resection. The hemostatic effect of CA was limited.

Biomolecular evidence of anti-inflammatory effects by Clematis mandshurica Ruprecht root extract in rodent cells

Ethnopharmacological relevanceClematis mandshurica Ruprecht root is widely used in Asia as an analgesic and anti-inflammatory agent. This research investigated the anti-inflammatory effects of Clematis mandshurica Ruprecht root extract (CRE) using RAW 264.7 macrophage cells and carrageenan- (CA-) induced rat paw edema. Materials and methodsProduction of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, nitric oxide (NO) and prostaglandin E2 (PGE2) in the culture supernatant, mRNA expression of TNF-α, IL-1β, IL-6, iNOS and COX-2, protein expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) in the extract were assayed. In addition, the effect of CRE on acute inflammation in vivo was observed using CA-induced rat hind paw edema assay. The changes on the histopathology and histomorphometry of hind paw skins—dorsum and ventrum pedis were observed using CA-treated rats. ResultsTreatment with CRE (0.25, 0.5, and 1mg/mL) resulted in inhibited levels of protein expression of lipopolysaccharide- (LPS-) induced iNOS, COX-2, NF-κB, and MAPKs (ERK, JNK, and p38) as well as production of TNF-α, IL-1β, IL-6, NO, and PGE2 induced by LPS. Consistent with these results, CRE reduced the LPS-induced expressions of these cytokines, iNOS and COX-2 at the mRNA levels in a dose-dependent manner. In particular, results of the CA-induced rat hind paw edema assay showed an anti-edema effect of CRE. In addition, treatment with CRE resulted in dose-dependent inhibition of CA-induced increases of skin thickness, mast cell degranulation, and infiltrated inflammatory, TNF-α, IL-1β, iNOS, and COX-2-positive cells in both dorsum and ventrum pedis skin, respectively. ConclusionsThese results demonstrate that CRE exhibits anti-inflammatory activities via decreasing production of pro-inflammatory mediators through suppression of the pathways of NF-κB and MAPKs in LPS-induced macrophage cells. In addition, results of the CA-induced rat hind paw edema assay show an anti-edema effect of CRE. Our findings also support the traditional use of CRE in the inflammatory symptoms of rheumatic arthritis and acute icteric hepatitis. Thus, CRE may have therapeutic potential for a variety of inflammation-mediated diseases and may be developed into potent anti-inflammatory drugs.

Androgen dependence of testicular and epididymal angiotensin converting enzyme.

Treatment with cadmium chloride (CdCl2) and cyproterone acetate (CA) depressed angiotensin converting enzyme (ACE) activity significantly in testes and epididymal regions of the adult rats compared to the corresponding untreated controls. Exogenous testosterone to CA-treated rats significantly increased the enzyme activity both in the testes and epididymis, the effect in the latter being very significant comparable to CA-treated and untreated controls. Testosterone failed to induce ACE activity in the testes and caput epididymis of 30 day-old immature rats, but the enzyme activity was detected in corpus and cauda epididymis. Our findings indicate that ACE activity in the testicular complex is possibly linked with androgen and is concerned with spermatogenesis and sperm maturation.

Increase in Nitric Oxide and Reductions in Blood Pressure, Protein Kinase C β II and Oxidative Stress by L-Carnitine: A Study in the Fructose-Fed Hypertensive Rat

Recently we showed that the administration of intraperitoneal L-carnitine (CA) has insulin-sensitizing effects in the high fructose-fed Wistar rat, a widely used model of metabolic syndrome. The present study was conducted to examine the regulatory effects of CA on blood pressure (BP) and related pressor mechanisms. Fructose-fed rats (FFR) showed elevated BP, cardiac hypertrophy, glucose intolerance, and increases in plasma glucose, insulin, free fatty acids (FFA), and angiotensin-converting enzyme (ACE) activity. They also showed increased protein kinase C βII (PKC βII) expression and oxidative stress in cardiac tissue. In plasma, decreased kallikrein enzyme activity and nitric oxide metabolites were observed, compared to control. Simultaneous treatment with CA (300 mg/Kg) mitigated these alterations. PKC βII expression was similar to that of control; the rats displayed normal BP and ACE activity, enhanced antioxidant protection, and close to normal values of metabolic parameters. The BP-lowering effect of CA was abolished when CA-treated rats were administered L-nitroarginyl methyl ester (L-NAME 6g/Kg). These observations suggest that the BP-lowering action of CA in this model could be attributed to multiple and interrelated mechanisms, such as an increase in NO and kinin availability, reduction in PKC action, and antioxidant protection.

Adjuvant-induced macrophage-dominant nephrotoxic serum nephritis in rats

To investigate cellular mechanisms responsible for the development of crescentic glomerular lesions, we have studied the effects of complete adjuvant (CA) on subnephritogenic nephrotoxic serum (NTS) nephritis (NTS-N) in Brown Norway rats. A subnephritogenic dose of NTS, 0.02 ml per rat, was intravenously injected into rats that were previously (14 days earlier) treated intradermally with CA, incomplete adjuvant, or PBS. Proteinuria developed by day 2 only in CA-treated rats. Also, severe glomerular lesions associated with cellular crescent formation developed by day 2 only in the CA-treated rats. The glomerular extent of infiltration of IL-1beta-positive cells, MCP-1 expression level, and the number of ED1 and PCNA double-positive activated macrophages peaked on day 4 and decreased thereafter. The numbers of T lymphocytes and polymorphonuclear neutrophils did not significantly increase throughout the experiments. These results indicate that CA can potently induce crescentic NTS-N characterized by the infiltration of activated macrophages, which presumably bind to rabbit IgG on the glomerular basement membrane and may play a critical role in the development of severe NTS-N associated with crescent formation.

Estradiol and calcium affect the growth hormone producing cells in female middle-aged rats

The effects of multiple doses of estradiol dipropionate (EDP) or calcium glucoheptonate (Ca) on the growth and function of pituitary somatotropes (GH cells) were studied. Female middle-aged rats were receiving i.p. EDP (0.625 mg i.p./kg b.w), or Ca (11.4 mg/kg b.w) every day for two weeks. Blood samples were collected for hormone analyses and pituitaries dissected for histological and morphometric evaluation 24 h after the last injection. GH-producing cells were examined using the peroxidase-antiperoxidase (PAP) immuno-histochemical procedure. Both EDP- and Ca-treatment significantly decreased all morphometric parameters of GH cells (p<0.05) in comparison with the corresponding controls. Serum concentration of growth hormone (GH) in EDP- or Ca-treated groups was lower by 65% and 13% (p<0.05) respectively comparing to the controls. The difference between all morphometric parameters of EDP- and Ca-treated rats was statistically significant (p<0.05) in relation to the controls. These findings suggest that multiple EDP, or Ca application affects (directly or indirectly) the control of growth and secretory activity of GH cells in middle-aged female rats.

Protective effect of glutamine from glucocorticoid-induced muscle atrophy occurs without alterations in circulating insulin-like growth factor (IGF)-I and IGF-binding protein levels.

We investigated whether the prevention of glucocorticoid-induced muscle atrophy by glutamine infusion is associated with alterations in serum levels of insulin-like growth factor (IGF)-I and its binding proteins (IGFBPs). Hormone (cortisol acetate [CA], 100 mg/kg body wt/day) and vehicle (carboxymethyl cellulose [CMC])-treated female rats were infused with either saline or glutamine (240 mM, 0.75 ml/hr) for a 7-day period. Glutamine infusion prevented over 70% of the skeletal muscle mass loss due to the glucocorticoid injections. Serum IGF-I concentrations, which were measured by radioimmunoassay (RIA) after acid solid-phase extraction of IGFBPs, were not significantly different among groups (range of means: 373-395 ng/ml). Saline/CA treatment resulted in a 2-fold increase in circulating levels of IGFBP-3 (38- to 50-kDa bands from ligand blotting measurements) versus the saline/CMC group. Levels of 30- to 32-kDa bands were increased by approximately 3-fold in the CA-treated rats. Immunoprecipitation studies suggested that the increase in the 30- to 32-kDa binding proteins were not due to elevated levels of IGFBP-1, -2, or -5. None of the treatments significantly modified circulating levels of IGFBP-4 (24 kDa). Glutamine infusion did not reverse the effects of glucocorticoids on circulating levels of 38- to 50- and 30- to 32-kDa IGFBPs. We conclude that the attenuation of glucocorticoid-induced muscle atrophy by glutamine infusion is not associated with changes in circulating levels of IGF-I or IGFBPs.

LEUCINE AS AN ANTAGONIST OF GLUCOCORTICOID-INDUCED MUSCLE ATROPHY 1300

This study was undertaken to examine whether leucine infusion is capable of preventing skeletal muscle atrophy associated with glucocorticoid treatment. Rats were administered hydrocortisone 21-acetate (CA) or the dosing vehicle(carboxymethyl cellulose (CMC) and were infused with saline (SAL) or leucine(LEU, 168 mM, 2.15 ml/hr) for 7 consecutive days. Quadriceps and gastrocnemius muscle masses following treatments showed the following pattern: LEU-CMC>SAL-CMC>LEU-CA>SAL-CA. When normalized to body mass, all groups were significantly different from each other with atrophy prevention≈50%. Leucine infusion resulted in higher serum leucine levels in CMC (52%) and in CA-treated (128%) rats as compared to their saline-infused counterparts. Serum glutamine or alanine levels were not altered by any treatment, but serum glutamate concentrations were reduced in CA-treated animals. Glutamine levels were similar (≈3.8 μmol/g) in fast-twitch red(deep quadriceps FTR) muscles among all groups. In fast-twitch white(superficial quadriceps FTW) muscles of saline-infused animals, glutamine concentrations were reduced by hormone treatment from 1.8±0.2 to 1.2±0.6 μmol/g. Leucine supplementation did not completely reverse this effect. Leucine infusion resulted in higher leucine levels in FTR(223±17 vs 97±9 nmol/g) and FTW (312±52 vs 104±17 nmol/g) muscles of glucocorticoid-treated rats. These data show the potential effects of leucine in counteracting muscle atrophy from glucocorticoids. The elevated skeletal muscle levels of leucine without concomitant changes in muscle glutamine may provide a sufficient stimulus to maintain a cellular environment, which is sufficient to attenuate the glucocorticoid-related catabolic effects on muscle mass.

Acute glucocorticoid effects on glycogen utilization, O2 uptake, and endurance.

This study was undertaken to determine the effects of increased substrate availability (glycogen + plasma fatty acids) by glucocorticoids on energy metabolism during exercise to exhaustion. Female rats received a single subcutaneous injection of cortisol acetate (CA) (100 mg.kg body wt-1) 21 h before treadmill running (30.8 m/min). At the start of exercise in the CA-treated rats, plasma fatty acids and liver glycogen were increased by 40%. Glycogen levels were also increased by CA treatment in slow-twitch soleus (61%), fast-twitch white vastus (38%), and fast-twitch red vastus lateralis (85%) muscles. Exercise time to exhaustion was increased by CA treatment (114 +/- 5 vs. 95 +/- 6 min, P less than 0.05). During the exercise, total glycogen depletion was greater in the CA-treated than in the control animals, whereas estimated relative rates of carbohydrate utilization (R = 0.90) were similar. However, while running the CA-treated group consumed 11% more O2 than the controls (P less than 0.05). These results show that a single injection of glucocorticoids is capable of improving endurance. Yet the increased O2 uptake during exercise may have minimized the impact of the initial increased availability of carbohydrates and fatty acids in prolonging exercise capacity. This decreased running economy by the CA-treated runners may be secondary to alterations in energy production or utilization.

Unaltered aerobic power and endurance following glucocorticoid-induced muscle atrophy

The present study was undertaken to evaluate whether the muscle atrophy associated with glucocorticoid excess results in a reduction in maximal oxygen uptake (VO2max) and endurance during exercise. Female rats were administered single subcutaneous injections of cortisone acetate (CA) (100 mg X kg-1 b.w.) or the vehicle (1% carboxymethyl cellulose) for 14 consecutive days. The weights of plantaris muscles (which were used as a marker of the atrophy) of CA-treated rats were 27% less than those of plantaris muscles in the vehicle-treated rats. This condition also produced a 12-fold increase in free serum glucocorticoid concentrations (cortisol) but did not alter serum androgen (testosterone) levels. Peak VO2 (ml X kg-1 X min-1) and endurance were greater in CA-treated vs vehicle-treated animals; however, these effects were shown to be a function of body weight loss. Homogenate oxygen uptakes in the presence of pyruvate or palmitate were also similar in slow-twitch soleus, fast-twitch red vastus, and fast-twitch white vastus lateralis muscles between CA- and vehicle-treated groups. These data provide no evidence to demonstrate that the catabolic actions of glucocorticoids in skeletal muscle result in a decrement in work capacity through at least 14 d of treatment.

Depletion of [3H]methyltrienolone cytosol binding in glucocorticoid-induced muscle atrophy.

The present study was undertaken to determine cytosol binding properties of [3H]methyltrienolone, a synthetic androgen, in comparison with [3H]dexamethasone, a synthetic glucocorticoid, under conditions of glucocorticoid excess in skeletal muscle. Male hypophysectomized rats received either seven daily subcutaneous injections of cortisone acetate (CA) (100 mg X kg-1 body wt) or the vehicle, 1% carboxymethyl cellulose. Following treatment, both [3H]dexamethasone and [3H]methyltrienolone-receptor concentrations were decreased from those in vehicle-treated rats by more than 90 and 80%, respectively, in CA-treated animals. Scatchard analysis of [3H]methyltrienolone binding in muscles of vehicle-treated animals became nonlinear at high concentrations of labeled ligand and were reanalyzed by a two-component binding model. The lower affinity, higher capacity component, which was attributed to binding of methyltrienolone to a "dexamethasone" component, disappeared in muscles of CA-treated rats and Scatchard plots were linear. Receptor concentrations of the higher affinity lower capacity "methyltrienolone" component were similar in muscles of vehicle-treated and CA-treated groups. From competition studies, the high relative specificities of glucocorticoids for [3H]methyltrienolone binding in muscles of vehicle-treated animals were markedly reduced by CA treatment. In addition, the binding specificity data also showed strong competition by progesterone and methyltrienolone for [3H]dexamethasone binding and estradiol-17 beta for [3H]methyltrienolone binding. These results demonstrate that most of the [3H]methyltrienolone binding is eliminated under in vivo conditions of glucocorticoid excess. Furthermore, the competitiveness of various steroids for receptor binding suggests that rat muscle may not contain classic (ligand-specific) glucocorticoid and androgen receptors.

Motor responses of cyproterone acetate-treated rat vas deferens to electrical field stimulation, noradrenaline and barium chloride.

The effect of cyproterone acetate (CA) was studied on the autonomic transmission and smooth muscle function of the rat vas deferens. In the CA-treated vas deferens, the endogenously released noradrenaline (NA) in response to electrical field stimulation or exogenously administered NA produced rhythmic contractions (lacking a tonic component) which were abolished by prazosin - a preferential postjunctional alpha-adrenoceptor blocker. The biphasic nature of the nonadrenergic response elicited on electrical field stimulation in CA-treated rats remained unaltered. Like in controls, yohimbine potentiated this response thereby demonstrating the presence of functional presynaptic alpha-adrenoceptors (inhibitory in nature). The postjunctional alteration on the membrane function appears to be specific to adrenergic stimulation alone, since both tonic and phasic components were demonstrated in the responses resulting from nonadrenergic stimulation or those produced by barium chloride.

Cyproterone acetate prevents translocation of the androgen receptor in the rat prostate

The translocation of the androgen receptor in prostatic tissue has been studied under the influence of different ligands (testosterone, methyltrienolone and cyproterone acetate) in vivo and in vitro. Nuclear and cytoplasmic androgen receptors were estimated using an exchange assay with [ 3 H]methyltrienolone ([ 3 H]R1881) l h and 16 h after injection in castrated rats of either 100 μg testosterone (T), 10 mg cyproterone acetate (CA) or the combination of T and CA. Within 1 h after T administration, nuclear receptor levels increased with a concomitant depletion of cytosol receptors. In the CA-treated rats nuclear receptor levels were not different from those of control castrated animals and there was no depletion of cytosol receptors. The combined treatment of T and CA resulted in a partial depletion of cytosol receptors and a simultaneous increase of nuclear receptors. The absence of an increase in nuclear androgen receptors in CA-treated animals cannot be explained by a delay in translocation, because even 16 h after CA injection, only a very small number of nuclear receptors were detectable. Incubation of minced prostatic tissue with [ 3H]CA or [ 3H]Rl881 resulted in receptor translocation only in the R1881 incubations and confirmed the in vivo results. Competition studies with different steroids and cytosol receptor (non-activated, 8S form in low salt gradient) or nuclear receptor (activated 3.6S form in high salt gradient) of prostatic tissue show that CA can compete with R1881 for specific androgen-binding sites with a similar relative binding affinity for both receptor preparations. The present results provide evidence that CA prevents translocation of the androgen receptor to the nucleus, although CA can be bound with similar affinities to the nuclear receptor and the cytoplasmic receptor. We propose that the anti-androgenic action of CA involves an inhibition of receptor translocation.

Effects of glucocorticoid on body growth and serum levels of somatomedin A in the rat.

Serum levels of somatomedin A, as measured by radioreceptor assay, and body weight gain were 86.5 +/- 9.2% and 166.9 +/- 7.8% (N = 5) of the initial values, respectively, after 18 days administration of 2.5 mg cortisone acetate (CA). These values were significantly lower than those for saline treated rats (P less than 0.005). Reduced serum somatomedin A and body growth rate were partially restored after halting the injection of CA. Combined administration of daily doses of 100 micrograms hGH with CA did not prevent the decrease in somatomedin activity in treated rats. This observation suggests that GH plays a minor (or no) role in the fall of serum somatomedin A in CA-treated rats. From these data we conclude that glucocorticoids reduce serum somatomedin by inhibiting the effect of GH on the generation of somatomedin.