Ichthyotoxic ARF after fish gallbladder ingestion: a large case series from Vietnam

Drug stewardship in chronic kidney disease to achieve effective and safe medication use

People living with chronic kidney disease (CKD) often experience multimorbidity and require polypharmacy. Kidney dysfunction can also alter the pharmacokinetics and pharmacodynamics of medications, which can modify their risks and benefits; the extent of these changes is not well understood for all situations or medications. The principle of drug stewardship is aimed at maximizing medication safety and effectiveness in a population of patients through a variety of processes including medication reconciliation, medication selection, dose adjustment, monitoring for effectiveness and safety, and discontinuation (deprescribing) when no longer necessary. This Review is aimed at serving as a resource for achieving optimal drug stewardship for patients with CKD. We describe special considerations for medication use during pregnancy and lactation, during acute illness and in patients with cancer, as well as guidance for the responsible use of over-the-counter drugs, herbal remedies, supplements and sick-day rules. We also highlight inequities in medication access worldwide and suggest policies to improve access to quality and essential medications for all persons with CKD. Further strategies to promote drug stewardship include patient education and engagement, the use of digital health tools, shared decision-making and collaboration within interdisciplinary teams. Throughout, we position the person with CKD at the centre of all drug stewardship efforts.

Acute Kidney Injury Following Ingestion of Raw Fish Gallbladder of Indian Crap (Labeo Rohita): Thirty Case Series During 1975-2018

Introduction

Ayurveda describes using desiccated and well-processed gallbladder of Indian carp (Labeorohita) as a traditional remedy for some diseases. People consume it irrationally following the hearsay advice for all types of chronic diseases.

Methods

Here we report 30 sporadic cases of acute kidney injury (AKI) following ingestion of raw gallbladder of Indian carp during 1975-2018 (44 years).

Results

Most of the victims were males (83.3%) with an average age of 37.7 years. The mean onset of symptoms was 2 to 12 hours after ingestion. All patients presented as acute gastroenteritis and AKI. Among them, 22 (73.33%) needed urgent dialysis, and 18 (81.81%) of them recovered with four (18.18%) deaths. Eight patients (26.6%) were managed conservatively, of which seven (87.5%) recovered with one (12.5%) death. Septicemia, myocarditis, and acute respiratory distress syndrome were the causes of death.

Conclusions

This longest four-decade case series highlights that indiscriminate ingestion of raw fish gallbladder by unqualified prescription results in toxic AKI with multiple organ dysfunction and death.

Suppressive effect of goat bile in Plasmodium berghei ANKA infection in mice

BACKGROUND AND AIM

Some individuals in Indonesia consume intact goat gallbladder to prevent and treat malaria. The acute and subacute toxicity tests of goat bile (GB) have shown mild diarrhea in mice. Therefore, this study aimed to evaluate the suppressive effect of GB on parasitemia, splenomegaly, hepatomegaly, and blood biochemistry to assess liver and kidney function in BALB/c mice infected with Plasmodium berghei ANKA.

MATERIALS AND METHODS

Fifty healthy mice were infected with P. berghei ANKA and divided into five groups. Mice in three groups were administered 0.5 mL of 25%, 50%, or 100% of GB by gavage. Animals in Group 4 were administered 187.2 mg/kg BW of dihydroartemisinin-piperaquine phosphate as a positive control (POS Group). Mice in fifth group were administered sterile water as negative (NEG) controls. Further, 30 uninfected mice were divided into groups 6-8 and administered GB as were mice in the first three groups. Group 9 included 10 uninfected and untreated animals as healthy controls. Treatments were administered in a 4-day suppressive test followed by daily observation of Giemsa-stained blood smears. On day 7, mice were sacrificed to measure the length and weight of spleens and livers, plasma levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN), and creatinine.

RESULTS

GB suppressed parasitemia but did not affect the size and weight of spleens or livers or plasma levels of AST and ALT compared to uninfected GB-treated and healthy control animals. Conversely, plasma levels of BUN and creatinine were suppressed and remained in the normal range in all groups of mice.

CONCLUSION

GB suppresses parasitemia with no significant impact on hepatic enzymes in GB-treated infected mice. Liver dysfunction in GB-treated infected mice was due to P. berghei rather than GB treatment.

Renal failure and hepatitis following ingestion of raw grass carp gallbladder: A case report

BACKGROUND

Fish gallbladder has long been used as a folk remedy in Asian countries. Multiple organ damage after ingestion of fish gallbladder resulting in near mortality has been known to us. Here, we describe a case of acute renal failure (ARF) and hepatitis due to grass carp gallbladder poisoning and review the literature.

CASE SUMMARY

A previously healthy, 50-year-old woman was admitted to our hospital with a 2-d history of generalized abdominal pain and repeated vomiting following ingestion of two raw grass carp gallbladders in an attempt to alleviate her cough. She developed anuria on day 4 with markedly elevated serum creatinine, urea, bilirubin, alanine aminotransferase, and aspartate aminotransferase. Based on thorough evaluation of her history and prompt biochemical investigations, we diagnosed her with ARF and hepatitis secondary to fish gallbladder poisoning. Her renal biopsy revealed acute tubular necrosis, following which she underwent six sessions of conventional hemodialysis due to renal failure. Supportive treatment with gastric mucosal protectant and liver protectant was administered for targeted organ protection. The patient’s liver function gradually recovered, and serum creatinine was 164 mmol/L at discharge on day 24. Over a follow-up period of 2 wk, her renal function completely recovered.

CONCLUSION

Physicians should be mindful of toxic complications of raw grass carp gallbladder ingestion and we should promote awareness to reduce incidences of food poisoning.

Analysis of factors related to prognosis and death of fish bile poisoning in China: A retrospective study

Fish bile has long been considered to have therapeutic benefits in folk medicine in some Asian countries. However, poisoning incidents and even death sporadically occurred when people consumed fish bile. Herein, we summarize the main characteristics of fish bile poisoning in China including clinical symptoms, treatment strategies and factors being associated with death and affecting prognosis, hoping to provide a reference for the diagnosis and treatment of fish bile poisoning, as well as forensic identification of death cases induced by fish bile poisoning. We suggest that the health authorities should make an effort to enhance people's awareness of the safety of traditional medicine like fish bile so as to reduce the incidence of adverse events.

Acute kidney injury with consumption of raw gall bladder of Indian carp fish (Labeo rohita): A single center study from India

AIM

This retrospective study examined the clinical presentation and outcome of all patients who presented with acute kidney injury (AKI) following consumption of uncooked fish gallbladder as folk medicine.

METHODS

We reviewed all cases admitted at our institute between 1 January 1997 and 31 December 2016 following ingestion of fish gallbladder (Indian carp/Labeo rohita).

RESULTS

A total 32 of patients were included, with a male: female ratio of 3:1 and mean age 44.34 ± 13.33 years. The mean number of gall bladder consumed was 4.59 ± 4.75. All 32 patients presented with hepatic and renal failure. The mean duration of onset of symptoms following ingestion was 6.47 ± 2.84 h. At the time of admission, urine output was 187.9 ± 141 mL/24 h, serum creatinine 11.66 ± 2.50 mg/dL, serum bilirubin 6.14 ± 3.91 mg/dL, serum glutamate-pyruvate transaminase (SGPT) 687 ± 458 IU/L and serum glutamic oxaloacetic transaminase (SGOT) 188 ± 181 IU/L. All but one patient required haemodialysis. Twenty-seven patients were discharged with recovering acute kidney injury while five patients died. Mean duration of hospital stay was 12.94 ± 8.31 days. Mean number of haemodialysis sessions received by patients was 4.59 ± 3.12. Interval between consumption and onset of symptoms, serum bilirubin and SGPT were found to be significantly different between those who survived and died.

CONCLUSION

Acute kidney injury associated with ingestion of raw fish gallbladder is associated with significant morbidity and mortality.

Kidney toxicity related to herbs and dietary supplements: Online table of case reports. Part 3 of 5 series

BACKGROUND

No tabular summary of potentially life-threatening, kidney-toxic dietary supplements (DS; includes herbs) based on PubMed case reports is currently available online and continually updated to forewarn United States consumers, clinicians, and companies manufacturing DS. The purpose of this review was to create an online research summary table of kidney toxicity case reports related to DS.

METHODS

Documented PubMed case reports (1966 to May 2016, and cross-referencing) of DS appearing to contribute to kidney toxicity were listed in "DS Toxic Tables." Keywords included "herb" or "dietary supplement" combined with "kidney" to generate an overview list, and possibly "toxicity" to narrow the selection. Case reports were excluded if they involved herb combinations (some exceptions), Chinese herb mixtures, teas of mixed herb contents, mushrooms, poisonous plants, self-harm, excessive doses (except vitamins/minerals), legal or illegal drugs, drug-herbal interactions, and confounders of drugs or diseases. Since commercial DS often include a combination of ingredients, they were treated separately; so were foods. A few foods with kidney-toxic effects were listed in a fourth table. The spectrum of herbal or DS-induced kidney injuries included kidney stones, nephritis, nephrotic syndrome, necrosis, acute kidney injury (AKI; previously known as acute renal failure [ARF]), chronic kidney disease, kidney transplant, and death.

RESULTS

Approximately 7 herbs (minus 4 no longer for sale) and 10 dietary supplements (minus 3 excluded due to excessive doses + germanium that is no longer sold) have been related to kidney injury case reports published in PubMed (+crosslisting) in the last 50 + years (1966 to May 2016). The implicated herbs include Chinese yew (Taxus celbica) extract, impila (Callilepis laureola), morning cypress (Cupressus funebris Endl), St. John's wort (Hypericum perforatum), thundergod vine (Tripterygium wilfordii hook F), tribulus (Tribulus terrestris) and wormwood (Artemisia herba-alba). No longer sold in the United States are chocolate vine or mu tong (Caulis aristolochiae), guang fang ji (Aristolochia fangchi), ma huang (Ephedra sinica), and Tenshin Tokishigyaku-ka-goshuyu-shokyo-to. The DS include bile (sheep), chlorella, chromium (Cr), CKLS, creatine, gallbladder (fish), glucosamine, hydrazine, N.O.-Xplode, Spanish fly, and excess intakes of vitamins A, C, and D. Germanium (Ge) is not available for sale. The top two DS with the largest number of reported publications, but not always case reports, in descending order, were the aristolochic acid-containing herbs guang fang ji (mistaken identity) and chocolate vine or mu tong. The remaining DS featured one to three publications over a 50+ year period. Numerous case reports were reported for kidney-toxic foods: djenkol bean, gallbladders (carp fish, pufferfish, & snake), and star fruit (only in chronic kidney disease patients), and uncooked yam powder or juice.

CONCLUSION

This online "DS Toxic Table" provides clinicians, consumers, and manufacturers with a list of herbs that could potentially contribute to kidney injuries.

Community Acquired Acute Kidney Injury from Edible Agents: Report from a Developing Country, Bangladesh

Toxin is a common cause of community acquired acute kidney injury (AKI) which includes environmental toxins like plant toxins as well as various drugs and chemicals which are usually ingested for medicinal as well as recreational purposes.

Averrhoa carambola(Star fruit/ Kamranga) andAvorrhoa bilimbiare two such commonly used traditional remedies. They belong to familyOxalidaecaeand contain high-levels of oxalic acid. AKI may occur after consuming concentrated juice due to deposition of oxalate crystals in the renal tubules.

Here we present two patients who developed AKI after ingestion of freshly made juice from A. bilimbi and star fruit. Both patients were diabetic and the juice was ingested on empty stomach with the belief of improving glycemic status. Initial presentation was GI upset in both scenarios. Patient with A. bilimbi toxicity had diabetic nephropathy and required hemodialysis. Renal biopsy revealed deposition of polarizable oxalate crystals in the patient who consumed A. bilimbi and acute tubular necrosis in the patient with star fruit toxicity. All cases regained normal renal function within three months.

We also present a patient who ingested raw fish gallbladder as a remedy for asthma. The patient presented with AKI within five days of ingestion and required hemodialysis. His highest serum creatinine was 10.4mg/dl and fell to 1.7 mg/dl after four weeks. Cyprinol and related compounds in fish gallbladder are thought to be the cause of acute tubular necrosis in such cases.

The fourth patient developed AKI with rhabdomyolysis after consuming a locally made energy drink. He also required dialysis and serum creatinine gradually improved from 7.2mg/dl to 1.4mg/dl at discharge. The possibility of toxicity of caffeine, adulteration with other chemicals or ascorbic acid toxicity causing oxalate nephropathy could not be excluded.

All four patients developed AKI caused after ingesting easily available products and are presented here for public awareness. We believe proper knowledge and education can reduce toxin induced AKI in our society.

Acute kidney injury from different poisonous substances

AIM

To report our experience of acute kidney injury (AKI) developed after exposure to poisonous substance.

METHODS

Retrospective study where data was collected from case records of patients coming to this institute during January 1990 to May 2016. This institution is a tertiary care center for renal care in the metropolitan city of Karachi, Pakistan. History of ingested substance, symptoms on presentation, basic laboratory tests on arrival, mode of treatment and outcome were recorded from all patients and are presented here. Patients developing AKI after snake envenomation or scorpion stings are not included in this study.

RESULTS

During studied period 184 cases of AKI developing after poisoning were seen at our institution. The largest group was from paraphenyline diamine poisoning comprising 135 patients, followed by methanol in 8, organophosphorus compounds in 5, paraquat in 5, copper sulphate in 5, tartaric acid in 4, phenobarbitone in 3 and benzodiazipines, datura, rat killer, fish gall bladder, arsenic, boiler water, ammonium dichromate, acetic acid and herbs with lesser frequency. In 8 patients multiple substances were ingested in combination. Renal replacement therapy was required in 96% of patients. Complete recovery was seen in 72.28% patients, 20% died during acute phase of illness.

CONCLUSION

It is important to report poisonous substances causing vital organ failure to increase awareness among general population as well as health care providers.

Fish gall bladder consumption presenting as acute renal failure

A forty two year old male was admitted with history of anuria and breathlessness following consumption of raw rohu fish gall bladder. He had azotemia and required hemodialysis. His renal failure improved over a period of about four weeks. Incidences have been reported from South East Asian countries associating consumption of raw rohu fish gall bladder with acute renal failure.

Clinical analysis of 156 cases of multiple organ failure caused by fish bile

OBJECTIVE

To analyze the clinical features and prognosis of patients suffering from fish bile poisoning.

METHODS

A total of 156 multiple organ failure (MOF) patients caused by fish bile poisoning were hospitalized in our department over the past 28 years. The patients' symptoms, examination results, treatment and outcomes were collected and analyzed.

RESULTS

All patients' first symptom was gastrointestinal discomfort, including unbearable nausea and intractable vomiting. The symptoms that followed were oliguria or anuria, edema, headache, fatigue, jaundice, palpitation, alimentary tract hemorrhage, gross hematuria, dyspnea, shock, tachycardia, bradycardia, arrhythmia, coma, and cardiac arrest. The symptom severity and cohort were different among different patients. Twenty-one cases received gastroscopy, which exhibited diffuse gastric mucosal bleeding. Twelve patients received renal biopsy, which exhibited focal necrosis of tubular epithelial cells. One patient received a liver biopsy, which exhibited extensive hepatocyte necrosis. All patients received blood purification therapy. Of the four patients who died, 4 out of 5 organs had failed. The general mortality rate was 2.6%.

CONCLUSIONS

Compared with the MOF caused by trauma and sepsis, the fish bile poisoning MOF has a much lower morality rate. However, patients with higher age, more underlying diseases, and more organ failure tended to have a worse prognosis.

Traditional Chinese Medicine Induced Liver Injury

Traditional Chinese Medicine (TCM) is popular around the world and encompasses many different practices with particular emphasis on herbal TCM. Using the PubMed database, a literature search was undertaken to assess the extent herbal TCM products exert rare hepatotoxicity. Analysis of reported cases revealed numerous specified herbal TCM products with potential hepatotoxicity. Among these were An Shu Ling, Bai Fang, Bai Xian Pi, Ban Tu Wan, Bo He, Bo Ye Qing Niu Dan, Bofu Tsu Sho San, Boh Gol Zhee, Cang Er Zi, Chai Hu, Chaso, Chi R Yun, Chuan Lian Zi, Ci Wu Jia, Da Chai Hu Tang, Da Huang, Du Huo, Gan Cao, Ge Gen, Ho Shou Wu, Hu Bohe You, Hu Zhang, Huang Qin, Huang Yao Zi, Hwang Geun Cho, Ji Gu Cao, Ji Ji, Ji Xue Cao, Jiguja, Jin Bu Huan, Jue Ming Zi, Kamishoyosan, Kudzu, Lei Gong Teng, Long Dan Xie Gan Tang, Lu Cha, Ma Huang, Mao Guo Tian Jie Cai, Onshido, Polygonum multiflorum, Qian Li Guang, Ren Shen, Sairei To, Shan Chi, Shen Min, Shi Can, Shi Liu Pi, Shou Wu Pian, Tian Hua Fen, White flood, Wu Bei Zi, Xi Shu, Xiao Chai Hu Tang, Yin Chen Hao, Zexie, Zhen Chu Cao, and various unclassified Chinese herbal mixtures. Causality was firmly established for a number of herbal TCM products by a positive reexposure test result, the liver specific scale of CIOMS (Council for International Organizations of Medical Sciences), or both. Otherwise, the quality of case data was mixed, especially regarding analysis of the herb ingredients because of adulteration with synthetic drugs, contamination with heavy metals, and misidentification. In addition, non-herbal TCM elements derived from Agaricus blazei, Agkistrodon, Antelope, Bombyx, Carp, Fish gallbladder, Phellinus, Scolopendra, Scorpio, and Zaocys are also known or potential hepatotoxins. For some patients, the clinical course was severe, with risks for acute liver failure, liver transplantation requirement, and lethality. In conclusion, the use of few herbal TCM products may rarely be associated with hepatotoxicity in some susceptible individuals, necessitating a stringent pretreatment evaluation of the risk/benefit ratio, based on results of multicenter, randomized, double-blind, placebo-controlled clinical trials.

Food poisonings by ingestion of cyprinid fish

Raw or dried gallbladders of cyprinid fish have long been ingested as a traditional medicine in the Asian countries, particularly in China, for ameliorating visual acuity, rheumatism, and general health; however, sporadic poisoning incidences have occurred after their ingestion. The poisoning causes complex symptoms in patients, including acute renal failure, liver dysfunction, paralysis, and convulsions of limbs. The causative substance for the poisoning was isolated, and its basic properties were examined. The purified toxin revealed a minimum lethal dose of 2.6 mg/20 g in mouse, when injected intraperitoneally. The main symptoms were paralysis and convulsions of the hind legs, along with other neurological signs. Liver biopsy of the euthanized mice clearly exhibited hepatocytes necrosis and infiltration of neutrophils and lymphocytes, suggesting the acute dysfunction of the liver. Blood tests disclosed the characteristics of acute renal failure and liver injury. Infrared (IR) spectrometry, fast atom bombardment (FAB) mass spectrometry, and 1H- and 13C-nuclear magnetic resonance (NMR) analysis indicated, a molecular formula of C27H48O8S, containing a sulfate ester group for the toxin. Thus, we concluded that the structure of carp toxin to be 5α-cyprinol sulfate (5α-cholestane-3α, 7α, 12α, 26, 27-pentol 26-sulfate). This indicated that carp toxin is a nephro- and hepato- toxin, which could be the responsible toxin for carp bile poisoning in humans.

Nephrotoxicity of alternative medicine practice

The use of alternative medicine is highly prevalent around the world; in many areas, this is so because of lack of access to, or trust in, Western medicine, and also because they are considered "natural" and therefore safe. The kidney is an organ vulnerable to toxic insults by virtue of its anatomy and function. Reports of nephrotoxicity associated with alternative medicine use encompass all forms of renal dysfunction, ranging from electrolyte abnormalities and proteinuria to acute and CKD, renal failure, and death. In countries where intensive care and dialysis support are not available, mortality is high. Mechanisms of alternative medicine-associated kidney injury include direct nephrotoxicity, which may be augmented by underlying predisposing conditions such as dehydration; contamination, or adulteration of remedies; inappropriate use or preparation of a remedy; or interactions with other medications. The use of alternative medicines is underreported to clinicians. Because many patients strongly believe in the powers of alternative medicines, it is important that alternative medicines not be demonized as a whole, but that their use and consequences be closely observed and reported to build a more comprehensive understanding of their impact in our clinical practice and to foster research on the potential harm or, in some cases, possible benefits.

Acute renal failure following consumption of fish gall bladder

A case of acute renal failure developing after consumption of fish gall bladder as a food item is reported. The patient recovered fully with conservative treatment and dialysis. The risk of acute kidney injury following ingestion of fish gall bladder, apparently for medical reasons is highlighted.

Non-drug-induced nephrotoxicity

Several drugs and other compounds can induce acute and/or chronic nephrotoxicity. The goal of this study was to review clinical features of nephrotoxicity induced by 'atypical' or 'unconventional' agents, such as environmental agents (metals, minerals, animals), food agents (mushrooms, aristolochic acid, medicinal traditional herbals, dietary supplements, melamine), drugs, and other products (ethylene glycol). Nephrotoxicity varies according to local background, dependent on different food and cultural customs, as well as to differences in local fauna and flora. The incidence of such a phenomenon is not well known. Many different pathophysiological pathways are involved, and the spectrum of renal lesions is rather wide. 'Epidemic nephrotoxicity' may occur, as recently illustrated by the melamine epidemics in Chinese infants receiving powdered milk formulas; a rapid reaction to unusual increased frequency of acute kidney injury and nephrolithiasis in young children has led to a rapid analysis from international experts, with subsequent recommendations for diagnosis and care. Nephrotoxicity should be considered when there is any unexplained renal impairment, especially in children.

Acute renal failure and hepatitis following ingestion of carp gallbladder

INTRODUCTION

Fish gallbladder has long been used as folk remedy in China. Poisoning due to carp gallbladder ingestion has been reported in many countries but the majority of cases are in Chinese journals. We report a case of grass carp gallbladder poisoning and review the literature, including the Chinese reports.

CASE REPORT

A 67 year old woman ingested a grass carp gallbladder and complained of nausea and epigastric pain in two hours, and had elevated alanine aminotransferase by 8 hours. She developed oliguria on day three and hemodialysis was performed on day five, following which she gradually recovered and was discharged on day 26.

DISCUSSION

Carp gallbladder contains 5 alpha-cyprinol sulphate, which is hepatotoxic and nephrotoxic. The exact mechanism of toxicity is unknown. Mild poisoning causes only gastroenteritis, liver and kidneys are affected in moderate poisoning, and multi-organ failure occurs in severe poisoning. The initial symptoms are nausea, vomiting, diarrhea and abdominal pain, which usually occur 5 to 12 hours after ingestion. Raised liver enzymes or jaundice occurs in 75% to 87% of patients. Acute renal impairment occurs in 72% to 87% of patients, usually on day 3 to 6. Treatment is supportive and often included hemodialysis.

CONCLUSION

The ingestion of grass carp gallbladder may result in transient hepatitis with subsequent acute renal failure. This case also illustrated the importance of understanding the use and potential serious complications of alternative medicines. Fish gallbladder poisoning should be considered in unexplained acute renal failure in Chinese and Asian patients.

5α-Bile alcohols function as farnesoid X receptor antagonists

The farnesoid X receptor (FXR) is a bile acid/alcohol-activated nuclear receptor that regulates lipid homeostasis. Unlike other steroid receptors, FXR binds bile acids in an orientation that allows the steroid nucleus A ring to face helix 12 in the receptor, a crucial domain for coactivator-recruitment. Because most naturally occurring bile acids and alcohols contain a cis-oriented A ring, which is distinct from that of other steroids and cholesterol metabolites, we investigated the role of this 5beta-configuration in FXR activation. The results showed that the 5beta-(A/B cis) bile alcohols 5beta-cyprinol and bufol are potent FXR agonists, whereas their 5alpha-(A/B trans) counterparts antagonize FXR transactivation and target gene expression. Both isomers bound to FXR, but their ability to induce coactivator-recruitment and thereby induce transactivation differed. These findings suggest a critical role for the A-ring orientation of bile salts in agonist/antagonist function.

Evolution of the pregnane x receptor: adaptation to cross-species differences in biliary bile salts

The pregnane X receptor (PXR) regulates the metabolism and elimination of bile salts, steroids, and xenobiotics. The sequence of the PXR ligand-binding domain diverges extensively between different animals, suggesting interspecies differences in ligands. Of the endogenous ligands known to activate PXR, biliary bile salts vary the most across vertebrate species, ranging from 27-carbon (C27) bile alcohol sulfates (early fish, amphibians) to C24 bile acids (birds, mammals). Using a luciferase-based reporter assay, human PXR was activated by a wide variety of bile salts. In contrast, zebrafish PXR was activated efficiently only by cyprinol sulfate, the major zebrafish bile salt, but not by recent bile acids. Chicken, mouse, rat, and rabbit PXRs were all activated by species-specific bile acids and by early fish bile alcohol sulfates. In addition, phylogenetic analysis using maximum likelihood demonstrated evidence for nonneutral evolution of the PXR ligand-binding domain. PXR activation by bile salts has expanded from narrow specificity for C27 bile alcohol sulfates (early fish) to a broader specificity for recent bile acids (birds, mammals). PXR specificity for bile salts has thus paralleled the increasing complexity of the bile salt synthetic pathway during vertebrate evolution, an unusual example of ligand-receptor coevolution in the nuclear hormone receptor superfamily.

Physicochemical and physiological properties of 5alpha-cyprinol sulfate, the toxic bile salt of cyprinid fish

5alpha-Cyprinol sulfate was isolated from bile of the Asiatic carp, Cyprinus carpio. 5alpha-Cyprinol sulfate was surface active and formed micelles; its critical micellization concentration (CMC) in 0.15 M Na+ using the maximum bubble pressure device was 1.5 mM; by dye solubilization, its CMC was approximately 4 mM. At concentrations >1 mM, 5alpha-cyprinol sulfate solubilized monooleylglycerol efficiently (2.1 molecules per mol micellar bile salt). When infused intravenously into the anesthetized rat, 5alpha-cyprinol sulfate was hemolytic, cholestatic, and toxic. In the isolated rat liver, it underwent little biotransformation and was poorly transported (Tmax congruent with 0.5 micromol/min/kg) as compared with taurocholate. 5alpha-Cyprinol, its bile alcohol moiety, was oxidized to its corresponding C27 bile acid and to allocholic acid (the latter was then conjugated with taurine); these metabolites were efficiently transported. 5alpha-Cyprinol sulfate inhibited taurocholate uptake in COS-7 cells transfected with rat asbt, the apical bile salt transporter of the ileal enterocyte. 5alpha-Cyprinol had limited aqueous solubility (0.3 mM) and was poorly absorbed from the perfused rat jejunum or ileum. Sampling of carp intestinal content indicated that 5alpha-cyprinol sulfate was present at micellar concentrations, and that it did not undergo hydrolysis during intestinal transit. These studies indicate that 5alpha-cyprinol sulfate is an excellent digestive detergent and suggest that a micellar phase is present during digestion in cyprinid fish.