Testosterone and dihydrotestosterone inhibit gallbladder motility through multiple signalling pathways

Non-genomic actions of steroid hormones on the contractility of non-vascular smooth muscles

Steroid hormones play an important role in physiological processes. The classical pathway of steroid actions is mediated by nuclear receptors, which regulate genes to modify biological processes. Non-genomic pathways of steroid actions are also known, mediated by cell membrane-located seven transmembrane domain receptors. Sex steroids and glucocorticoids have several membrane receptors already identified to mediate their rapid actions. However, mineralocorticoids have no identified membrane receptors, although their rapid actions are also measurable. In non-vascular smooth muscles (bronchial, uterine, gastrointestinal, and urinary), the rapid actions of steroids are mediated through the modification of the intracellular Ca2+ level by various Ca-channels and the cAMP and IP3 system. The non-genomic action can be converted into a genomic one, suggesting that these distinct pathways may interconnect, resulting in convergence between them. Sex steroids mostly relax all the non-vascular smooth muscles, except androgens and progesterone, which contract colonic and urinary bladder smooth muscles, respectively. Corticosteroids also induce relaxation in bronchial and uterine tissues, but their actions on gastrointestinal and urinary bladder smooth muscles have not been investigated yet. Bile acids also contribute to the smooth muscle contractility. Although the therapeutic application of the rapid effects of steroid hormones and their analogues for smooth muscle contractility disorders seems remote, the actions and mechanism discovered so far are promising. Further research is needed to expand our knowledge in this field by using existing experience. One of the greatest challenges is to separate genomic and non-genomic effects, but model molecules are available to start this line of research.

Serum Bile Acids Concentrations and Liver Enzyme Activities after Low-Dose Trilostane in Dogs with Hyperadrenocorticism

Hyperadrenocorticism (HAC) often leads to vacuolar hepatopathy. The impact of trilostane treatment on serum total bile acids (SBAs) concentrations in dogs with HAC remains unknown. This study investigated SBAs concentrations in healthy dogs and those with HAC following trilostane therapy. Ten healthy dogs and fifteen dogs with HAC were prospectively enrolled. A biochemistry profile and pre- and post-prandial SBAs concentrations were determined in each dog. Dogs with HAC were reassessed at 1 and 3 months after the initiation of trilostane treatment. Dogs with HAC had significantly higher serum ALT, ALP, and GGT activities, and cholesterol, triglyceride, and pre-prandial SBAs concentrations compared to healthy dogs. After 3 months of trilostane treatment, polyuria/polydipsia and polyphagia were completely resolved in 42.8% and 35.7%, respectively. Significant improvements in serum ALT and ALP activities and cholesterol concentrations were observed within 1-3 months of trilostane treatment. However, pre- and post-prandial SBAs concentrations did not significantly decrease. These findings suggest that treatment with low-dose trilostane for 3 months appears to reduce serum liver enzyme activities, but not SBAs concentrations. Further investigation is warranted to explore the effects of low-dose trilostane treatment on SBAs concentrations for a longer duration or after achieving appropriate post-ACTH cortisol levels.

Androgens and Non-Genomic vascular responses in hypertension

Arterial hypertension is a global public health concern. In the last few years, the interest in androgen deficiency has been growing, and the association between androgens and high blood pressure (BP) is still controversial. One purpose of this review was to summarize the available findings in order to clarify whether male sex steroid hormones have beneficial or harmful effect on BP. The second purpose was to enhance the recognition of the acute non-genomic sex-independent vasorelaxing effect of androgens. Remarkably, BP variation is expected to be a consequence of the androgen-induced vasorelaxation which reduces systemic BP; hence the in vivo vasodepressor, hypotensive, and antihypertensive responses of androgens were also analyzed. This article reviews the current understanding of the physiological regulation of vascular smooth muscle contractility by androgens. Additionally, it summarizes older and more recent data on androgens, and some of the possible underlying mechanisms of relaxation, structural-functional differences in the androgen molecules, and their designing ability to induce vasorelaxation. The clinical relevance of these findings in terms of designing future therapeutics mainly the 5-reduced metabolite of testosterone, 5β-dihydrotestosterone, is also highlighted. Literature collected through a PubMed database search, as well as our experimental work, was used for the present review.

The Flavone Luteolin, an Endocrine Disruptor, Relaxed Male Guinea Pig Gallbladder Strips

Background

Luteolin (3',4',5,7-tetrahydroxyflavone) is a flavone with a yellow crystalline appearance present in numerous plants such as broccoli, green chili, and carrot. Luteolin is considered to be an endocrine disruptor with potent estrogen agonist activity and potent progesterone antagonist activity. Luteolin has effects on smooth muscle. Luteolin relaxed guinea pig trachea smooth muscle as it inhibited both phosphodiesterase and reduced intracellular Ca²⁺. Luteolin also caused vasorelaxation in rat thoracic aorta smooth muscle by inhibiting intracellular Ca²⁺ release, inhibition of sarcolemmal Ca²⁺ channels, and activation of K⁺ channels. Luteolin or its glycosides from artichoke extracts may have an ameliorating effect on irritable bowel syndrome. The purpose of this study was to determine if luteolin had an effect on gallbladder motility.

Methods

An in vitro pharmacologic technique was utilized. Either cholecystokinin octapeptide (CCK) or KCl were used to induce tension in male guinea pig gallbladder strips maintained in Sawyer-Bartlestone chambers. Luteolin relaxed either the CCK- or KCl-induced tension in a concentration dependent manner. Various blockers were added to the chambers to determine which second messenger system(s) mediated the observed relaxation. Paired t-tests were used for statistical analysis. Differences between mean values of P < 0.05 were considered significant.

Results

Treatment of the gallbladder strips with luteolin prior to either KCl or CCK significantly (P < 0.001) decreased the amount of either KCl- or cholecystokinin-induced tension. The 2-aminoethoxydiphenylborane was used to ascertain if the release of intracellular Ca²⁺ mediated the luteolin-induced relaxation. It significantly (P < 0.001) decreased the amount of luteolin-induced relaxation. To ascertain if PKA mediated the luteolin-induced relaxation, PKA inhibitor 14-22 amide myristolated was used. It significantly (P < 0.01) reduced the amount of luteolin-induced relaxation. Neither KT5823, N^G-methyl-L-arginine acetate salt, genistein, tetraethylammonium, nor fulvestrant had a significant effect. To ascertain if PKC mediated the luteolin-induced relaxation, the PKC inhibitors bisindolymaleimide IV and chelerythrine Cl^- were used together. They had no significant effect.

Conclusions

Luteolin relaxed cholecystokinin- or KCl-induced tension by blocking extracellular Ca²⁺ entry as well as intracellular Ca²⁺ release. In addition, the actions of PKA are also involved in mediating the luteolin effect.

Association between cholesterol gallstones and testosterone replacement therapy in a patient with primary hypogonadism

A 16-year-old boy had a past medical history of primary hypogonadism, due to bilateral anorchia. He presented with gallstones located in the gallbladder and a mild dilatation of the intrahepatic biliary tree. The histology study reported cholesterol gallstones. The patient had been treated with testosterone replacement therapy since infancy. We suggest a possible correlation between testosterone replacement therapy and the presence of cholesterol gallstones.

Gallbladder motility and the sex of the guinea pig

Progesterone (P), 17β‐estradiol (E2), and dihydrotestosterone (DHT) affect gallbladder motility. When gallbladders were taken from women and men, women had more estrogen and P receptors than men. Both P and E2 had an inhibitory effect upon gallbladder contractility in men and premenopausal and postmenopausal women. Similar findings have been reported in gallbladder strips from male and female guinea pigs. In the present study, there was no significant difference in the amount of E2‐, P‐, or DHT‐induced relaxation of CCK‐induced tension when the responses in gallbladder strips from male and female guinea pigs were compared. Three metabolites of P were used: 17‐hydroxyprogesterone (17‐P), 20α‐hydroxyprogesterone (20‐P), and 21‐hydroxyprogesterone (21‐P). There was no significant difference in the responses from strips from male and female guinea pigs. In order to determine if the effects of E2 and P were additive, strips from male animals were exposed to either E2 or P and the amount of relaxation recorded. After recovery, the strips were exposed to E2 or P in reverse order to ensure the order of treatment had no effect. Then, the strips were treated with both E2 and P simultaneously and the relaxation recorded. This procedure was repeated with strips from female guinea pigs. The effect of E2 and P was found to be additive; however, the response of the strips from each sex were not significantly different. It is concluded that the sex of the guinea pig has no significant effect on the response to the sex hormones used.

Androgen actions on endothelium functions and cardiovascular diseases

The roles of androgens on cardiovascular physiology and pathophysiology are controversial as both beneficial and detrimental effects have been reported. Although the reasons for this discrepancy are unclear, multiple factors such as genetic and epigenetic variation, sex-specificity, hormone interactions, drug preparation and route of administration may contribute. Recently, growing evidence suggests that androgens exhibit beneficial effects on cardiovascular function though the mechanism remains to be elucidated. Endothelial cells (ECs) which line the interior surface of blood vessels are distributed throughout the circulatory system, and play a crucial role in cardiovascular function. Endothelial progenitor cells (EPCs) are considered an indispensable element for the reconstitution and maintenance of an intact endothelial layer. Endothelial dysfunction is regarded as an initiating step in development of atherosclerosis and cardiovascular diseases. The modulation of endothelial functions by androgens through either genomic or nongenomic signal pathways is one possible mechanism by which androgens act on the cardiovascular system. Obtaining insight into the mechanisms by which androgens affect EC and EPC functions will allow us to determine whether androgens possess beneficial effects on the cardiovascular system. This in turn may be critical in the prevention and therapy of cardiovascular diseases. This article seeks to review recent progress in androgen regulation of endothelial function, the sex-specificity of androgen actions, and its clinical applications in the cardiovascular system.

Protective Effect of DHT on Apoptosis Induced by U18666A via PI3K/Akt Signaling Pathway in C6 Glial Cell Lines

Various useful animal models, such as Alzheimer's disease and Niemann-Pick disease, were provided by U18666A. However, the pathogenesis of U18666A-induced diseases, including U18666A-mediated apoptosis, remains incompletely elucidated, and therapeutic strategies are still limited. Dihydrotestosterone (DHT) has been reported to contribute to the prevention and treatment of neurodegenerative disorders. Our study investigated the neuroprotective activity of DHT in U18666A-related diseases. Apoptosis of C6 cells was detected by Hoechst 33258 fluorescent staining and flow cytometry with annexin V-FITC/PI dual staining. Cell viability was assessed using Cell Counting Kit-8. Expression of apoptosis-related proteins, such as Akt, seladin-1, Bcl-2 family proteins, and caspase-3, was determined using Western blot. Our results demonstrated that the apoptotic rate of C6 cells significantly increased after U18666A addition, but was remarkably reduced after DHT treatment. Pretreatment with DHT attenuated U18666A-induced cell viability loss. PI3K inhibitor LY294002 could suppress DHT anti-apoptotic effect. Furthermore, we discovered that U18666A could significantly downregulate seladin-1 expression in a dose-dependent manner, but no significant change was observed in Bcl-xL, Bax, and P-Akt protein expressions. Compared with U18666A-treated group, the expression of P-Akt, seladin-1, and Bcl-xL significantly increased, and the expression of Bax and caspase-3 remarkably reduced after DHT treatment. However, in the presence of LY294002, the effect of DHT was reversed. In conclusion, we found that seladin-1 may take part in U18666A-induced apoptosis. DHT may inhibit U18666A-induced apoptosis by regulating downstream apoptosis-related proteins including seladin-1, caspase-3, Bcl-xL, and Bax through activation of the PI3K/Akt signal pathway.

The Resveratrol-induced Relaxation of Cholecystokinin Octapeptide- or KCl-induced Tension in Male Guinea Pig Gallbladder Strips Is Mediated Through L-type Ca2+Channels

Background/Aims

Resveratrol (3,5,4′-trihydroxystilbene) is a polyphenolic compound (stilbene) and a phytoalexin. The purpose of this study was to determine the mechanism which mediated the resveratrol-induced relaxation of cholecystokinin octapeptide- or KCl-induced tension in male guinea pig gallbladder strips.

Methods

Gallbladder strips were prepared and suspended in in vitro chambers filled with Krebs-Henseleit solution. The strips were attached to force displacement transducers, and the changes in tension were recorded on a polygraph. All reagents were added directly into the chambers.

Results

To determine if intracellular Ca²⁺ release mediated the resveratrol-induced relaxation of cholecystokinin octapeptide-induced tension, 2-aminoethoxydiphenylborane (2-APB) was used. 2-APB significantly (P < 0.01) decreased the amount of RSVL-induced relaxation. To determine if protein kinase A (PKA) mediated the resveratrol-induced relaxation, PKA inhibitor 14-22 amide myristolated (PKA-IM) was used. PKA-IM had no effect on resveratrol-induced relaxation. Neither KT5823, N^G-methyl-L-arginine acetate salt, a nitric oxide synthase inhibitor, nor fulvestrant had a significant effect on the amount of resveratrol-induced relaxation. Genistein, a protein tyrosine kinase inhibitor, significantly (P < 0.01) increased the RSVL-induced relaxation. To determine if protein kinase C mediated the RSVL-induced relaxation, the protein kinase C inhibitors bisindolymaleimide IV and chelerythrine Cl- were used together, and a significant (P < 0.05) increase in resveratrol-induced relaxation was observed. The pretreatment of the strips with resveratrol significantly (P < 0.001) decreased the amount of KCl- and cholecystokinin octapep-tide-induced tension.

Conclusions

Resveratrol-induced relaxation is mediated by its effects on L-type Ca²⁺ channels and intracellular Ca²⁺ release.

The flavonoid chrysin, an endocrine disrupter, relaxes cholecystokinin- and KCl-induced tension in male guinea pig gallbladder strips through multiple signaling pathways

The bioflavonoids have effects on vascular smooth muscle and gastrointestinal smooth muscle. The flavone and phytoestrogen, chrysin, has been shown to have a vasorelaxant effect on resistance blood vessels. This effect was mediated by nitric oxide (NO). Chrysin inhibited aromatase/estrogen biosynthesis in postmenopausal women. The purpose of this study was to determine if chrysin had an effect on cholecystokinin- or KCl-induced tension in male guinea pig gallbladder strips. In addition, the second messenger(s) system(s) that mediated the effect were to be determined. A pharmacologic approach was used. Male guinea pig gallbladder strips were placed in in vitro chambers filled with Krebs solution, maintained at 37 °C, and gassed with 95% O2-5% CO2. Changes in tension were recorded using a polygraph. It was shown that the PKA/cAMP second messenger system mediated part of the observed chrysin-induced relaxation of cholecystokinin-induced tension, the PKC system also mediated part of the relaxation, and the inhibition of both extracellular Ca(2+) entry and intracellular Ca(2+) release also mediated the chrysin-induced relaxation. This is the first report of chrysin having an effect on gallbladder smooth muscle contraction.

The association between gall bladder mucoceles and hyperlipidaemia in dogs: a retrospective case control study

The diagnosis of gall bladder mucoceles (GM) in dogs has become increasingly frequent in veterinary medicine. Primary breed-specific hyperlipidaemia is reported in Shetland Sheepdogs and Miniature Schnauzers, breeds in which GM are known to occur more frequently than in other breeds. The objective of this study was to evaluate the association between GM and hyperlipidaemia in dogs. The study design was a retrospective case control study. Medical records of dogs diagnosed with GM at the Veterinary Medical Centre of The University of Tokyo between 1 April 2007 and 31 March 2012, were reviewed. Fifty-eight dogs with GM and a record of either serum cholesterol, triglyceride, or glucose concentrations were included in the study. Hypercholesterolaemia (15/37 cases; odds ratio [OR]: 2.92; 95% confidence interval [CI]: 1.02-8.36) and hypertriglyceridaemia (13/24 cases; OR: 3.55; 95% CI:1.12-15.91) showed significant association with GM. Pomeranians (OR: 10.69), American Cocker Spaniels (OR: 8.94), Shetland Sheepdogs (OR: 6.21), Miniature Schnauzers (OR: 5.23), and Chihuahuas (OR: 3.06) were significantly predisposed to GM. Thirty-nine out of 58 cases had at least one concurrent disease, including pancreatitis (five cases), hyperadrenocorticism (two cases), and hypothyroidism (two cases). A significant association between GM and hyperlipidaemia was confirmed, suggesting that hyperlipidaemia may play a role in the pathogenesis of GM.

Targeting membrane androgen receptors in tumors

INTRODUCTION

In the last decade androgen actions that are originated from non-genomic, rapid signaling have been described in a large number of cell models and tissues. These effects are initiated through the stimulation of membrane androgen-binding sites or receptors (mAR). Although the molecular identity of mARs remains elusive, their activation is known to trigger multiple non-genomic signaling cascades and to regulate numerous cell responses. In recent years specific interest is being paid to the role of mARs in tumors. Specifically, it was demonstrated that mAR activation by non-permeable testosterone conjugates induced potent anti-tumorigenic responses in prostate, breast, colon and glial tumors. In addition, in vivo animal studies further emphasized the potential clinical importance of these receptors.

AREAS COVERED

This review will summarize the current knowledge on the mAR-induced non-genomic, rapid androgen actions. It will focus on the molecular signaling pathways governed by mAR activation, discuss latest attempts to elucidate the molecular identity of mAR, address the plethora of cell responses initiated by mAR and evaluate the potential role of mAR and mAR-specific signaling as possible therapeutic targets in tumors.

EXPERT OPINION

mAR and mAR-induced specific signaling may represent novel therapeutic targets in tumors through the development of specific testosterone analogs.

A comparison of the effects of various sex steroids on cholecystokinin- and KCl-induced tension in female guinea pig gallbladder strips

Estrogen (E) has been shown to have an inhibitory effect on the contractility of gastrointestinal smooth muscle, including the gallbladder. During pregnancy E and progesterone (P) levels are elevated. A biliary stasis may develop during pregnancy that is characterized by an increase in the fasting and residual volumes and by a decrease in emptying capacity. This study investigates the effect of 17β-estradiol (E2), dihydrotestosterone (DHT), P, 17-hydroxyprogesterone (17-P), and a P metabolite, 20α-hydroxyprogesterone (20-P) on contraction in female guinea pig gallbladder strips. DHT, P, 17-P, 20-P, and E2 each induced a concentration-dependent relaxation of cholecystokinin octapeptide (CCK) induced tension. DHT, E2, and P also induced a concentration-dependent relaxation of KCl-induced tension. When the response to E2 was compared to strips from young female guinea pigs with those taken from guinea pigs in late pregnancy, there was no significant difference in the response to either 50 or 100 μM E2; however, 10 μM E2 caused a significant increase (p<0.05) in the amount of relaxation in strips from pregnant guinea pigs. Treatment of the strips from young guinea pigs with PKA inhibitor 14-22 amide myristolated had no significant effect on the E2-induced relaxation. Treatment of the strips with 2-APB, an inhibitor of IP3 induced Ca(2+) release, produced a significant (p<0.001) increase in the amount of E2-induced relaxation when either CCK or KCl were used. Neither KT5823, a PKG inhibitor, nor L-NMMA, a nitric oxide (NO) synthase inhibitor, had a significant effect on the E2-induced relaxation. Bisindolymaleimide IV and chelerythrine Cl(-), PKC blockers, were used in combination with no significant effect on the amount of CCK-induced tension, but significantly (p<0.01) increased the amount of E2-induced relaxation. When either E2 or P were added to the chambers 3 min prior to either CCK or KCl, a significant decrease (p<0.001) in the amount of tension generated was observed. The inhibition of extracellular Ca(2+) entry mediates both P-induced and E2-induced relaxation of CCK- and KCl-induced tension in female guinea pig gallbladder strips.

Impaired gallbladder motility and the effect of metformin therapy in patients with polycystic ovary syndrome

OBJECTIVE

  Impaired gallbladder (GB) emptying is a well-documented contributor to gallstone formation. The aim of this study was to evaluate GB motility in patients with polycystic ovary syndrome (PCOS).

METHODS

  The study population consisted of 36 PCOS patients and 20 healthy controls. GB volume was calculated using the ellipsoid formula (π/6 × L × D × W) after three-dimensional measurements were made by ultrasound [length (L), width (W) and depth (D)]. Following the determination of fasting GB volume (V0), patients were given a standard liquid meal. GB volume measurement was then repeated after 10, 20, 30, 40, 50, 60, 75 and 90 min. Gallbladder ejection fraction (GBEF) was calculated after each measurement. PCOS patients were re-evaluated after a 12-week course of metformin therapy at a dose of 1000 mg/day.

RESULTS

  Mean baseline GB volume (V0) was significantly higher in the patient group compared to the control group (27·2 ± 12·5 cm(3) vs 13·3 ± 7·0 cm(3) , P < 0·001). While baseline GBEF values were similar between groups, increases in GBEF were significantly lower in the PCOS group starting from 20 min after consumption of a standard test meal. A 12-week course of metformin therapy resulted in significant improvements in GB volume and GBEF values with a reversal of metabolic and hormonal abnormalities.

CONCLUSION

  For the first time in the literature, we managed to demonstrate impaired GB motility in patients with PCOS. Metformin therapy not only improves the metabolic and hormonal imbalances associated with PCOS but also has a positive influence on GB motility.

Testosterone and coronary artery disease

Cardiovascular disease remains the leading cause of death in most of the developed world despite advances in both prevention and treatment. At the same time, the incidence rates of cardiovascular disease differ greatly between the genders, with men more likely than women to manifest ischemic heart disease. This observation has prompted new research initiatives to explain the discrepancy in heart disease prevalence and incidence between the sexes. Whether androgens affect cardiovascular disease adversely remains a contentious issue, with some data pointing to a deleterious effect of androgens on lipid profiles, and other studies revealing androgens' possible benefits on cardiovascular function. This review will examine the relationship between the endogenous production of androgen as well as the exogenous replacement of testosterone in men and the possible links to cardiovascular disease. The role of testosterone in male cardiovascular health is not completely understood, and additional studies are needed to explain its effect on atherosclerosis and its complications.

17β-Estradiol relaxes cholecystokinin- and KCl-induced tension in male guinea pig gallbladder strips

Estrogen has been shown to have an inhibitory effect on the contractility of gastrointestinal smooth muscle, including the gallbladder. Since estrogen and progesterone levels are elevated during pregnancy, a biliary stasis may develop during pregnancy that is characterized by an increase in the fasting and residual volumes and by a decrease in emptying capacity. This study investigates the effect of 17β-estradiol (E2) on contraction in male guinea pig gallbladder strips. E2 induced a concentration-dependent relaxation of either CCK-induced tension or KCl-induced tension. Pretreatment of the strips with PKA inhibitor 14-22 amide myristolated had no significant effect on the E2-induced relaxation. Pretreatment of strips with 2-APB, and inhibitor of IP(3) induced Ca(2+) release, produced a significant (p<0.001) increase in the amount of E2-induced relaxation when either CCK or KCl were used to induce tension. KT5823, an inhibitor of PKG, also significantly (p<0.001) increased the amount of E2-induced relaxation. Genistein, an inhibitor of protein tyrosine kinase, had no significant effect on the E2-induced relaxation. Bisindolymaleimide IV and chelerythrine Cl- when used in combination had no significant effect on the amount of CCK-induced tension, but significantly (p<0.001) increased the amount of E2-induced relaxation. When E2 was added to the chambers prior to either CCK or KCl, a significant decrease (p<0.001) in the amount of tension generated was observed. The inhibition of extracellular Ca(2+) entry mediates the E2-induced relaxation of CCK- and KCl-induced tension in male guinea pig gallbladder strips.

Gall bladder mucoceles and their association with endocrinopathies in dogs: a retrospective case-control study

OBJECTIVE

To investigate the relationship between endocrinopathies and diagnosis of gall bladder mucocele in dogs via a retrospective case-control study.

METHODS

Records of 78 dogs with a surgical or ultrasonographic diagnosis of gall bladder mucocele were examined for the presence or absence of hyperadrenocorticism, hypothyroidism and diabetes mellitus. Two age- and breed-matched controls for each gall bladder mucocele dog (156 total control dogs) were examined for the same concurrent diseases. A matched case-control analysis was performed using conditional logistic regression.

RESULTS

The odds of mucocele in dogs with hyperadrenocorticism were 29 times that of dogs without hyperadrenocorticism (P=0.001; 95 per cent CI 3.8, 219.9). No difference was found between dogs with and without diabetes mellitus. Although a significant association was found between gall bladder mucocele and hypothyroidism, potential observation bias was also identifi ed.

CLINICAL SIGNIFICANCE

Hyperadrenocorticoid dogs that were presented for acute illness with laboratory evidence of hepatobiliary disease should undergo evaluation for the presence of a biliary mucocele. Dogs diagnosed with a gall bladder mucocele should be screened for concurrent hyperadrenocorticism if clinical suspicion exists.