Protective effect of metformin on lithium-induced nephrogenic diabetes insipidus: An experimental study in rats.

BACKGROUND: Lithium is widely used in the treatment of bipolar disorders and may lead to nephrogenic diabetes insipidus (NDI), following long-term treatment. Metformin is considered the preferred initial therapy for patients with type 2 diabetes mellitus (T2D). OBJECTIVES: To investigate the protective effect of metformin on the kidney damage caused by lithium administration. MATERIAL AND METHODS: Using an animal model of chronic lithium-induced NDI, rats were divided into 4 groups: sham, metformin, lithium, and lithium + metformin. The effects of these treatments were examined using serum electrolytes, blood and tissue total antioxidant status, total oxidant status, the oxidative stress index, urine and blood osmolality, and tissue aquaporin-2 (AQP2) levels. Additionally, histopathological changes, including congestion, hydropic swelling, tubular necrosis, tubular atrophy, and Bowman's capsule dilatation, were evaluated. The total histopathological score was obtained by summing the scores for each pathological finding. RESULTS: In the lithium group, biochemical variables indicating NDI, including sodium, chloride and blood osmolality, increased, and urine osmolality decreased, compared to the sham group. With metformin treatment, the blood osmolality decreased from 328.17 mOsm/kg to 306.33 mOsm/kg, and urine osmolality increased from 349.67 mOsm/kg to 754.50 mOsm/kg (p = 0.004 and p = 0.001, respectively). Tissue AQP2 levels decreased with lithium administration but stabilized with metformin treatment. Additionally, in comparison to the lithium group, the total histopathological score in the metformin group declined from 8.0 to 2.0 (p = 0.002). CONCLUSIONS: Metformin may help protect the kidneys from lithium-induced NDI through the AQP2 regulating effect and a reduction in oxidative stress.

Chloroquine attenuates lithium-induced NDI and proliferation of renal collecting duct cells.

Lithium is widely used in psychiatry as the golden standard for more than 60 yr due to its effectiveness. However, its adverse effect has been limiting its long-term use in clinic. About 40% of patients taking lithium develop nephrogenic diabetes insipidus (NDI). Lithium can also induce proliferation of collecting duct cells, leading to microcyst formation in the kidney. Lithium was considered an autophagy inducer that might contribute to the therapeutic benefit of neuropsychiatric disorders. Thus, we hypothesized that autophagy may play a role in lithium-induced kidney nephrotoxicity. To address our hypothesis, we fed mice with a lithium-containing diet with chloroquine (CQ), an autophagy inhibitor, concurrently. Lithium-treated mice presented enhanced autophagy activity in the kidney cortex and medulla. CQ treatment significantly ameliorated lithium-induced polyuria, polydipsia, natriuresis, and kaliuresis accompanied with attenuated downregulation of aquaporin-2 and Na+-K+-2Cl- cotransporter protein. The protective effect of CQ on aquaporin-2 protein abundance was confirmed in cultured cortical collecting duct cells. In addition, we found that lithium-induced proliferation of collecting duct cells was also suppressed by CQ as detected by proliferating cell nuclear antigen staining. Moreover, both phosphorylated mammalian target of rapamycin and ß-catenin expression, which have been reported to be increased by lithium and associated with cell proliferation, were reduced by CQ. Taken together, our study demonstrated that CQ protected against lithium-induced NDI and collecting duct cell proliferation possibly through inhibiting autophagy.

Systematic review and practical guideline for the prevention and management of the renal side effects of lithium therapy.

Lithium is the first line therapy of bipolar mood disorder. Lithium-induced nephrogenic diabetes insipidus (Li-NDI) and lithium nephropathy (Li-NP, i.e., renal insufficiency) are prevalent side effects of lithium therapy, with significant morbidity. The objective of this systematic review is to provide an overview of preventive and management strategies for Li-NDI and Li-NP. For this, the PRISMA guideline for systematic reviews was used. Papers on the prevention and/or treatment of Li-NDI or Li-NP, and (influenceable) risk factors for development of Li-NDI or Li-NP were included. We found that the amount of evidence on prevention and treatment of Li-NDI and Li-NP is scarce. To prevent Li-NDI and Li-NP we advise to use a once-daily dosing schedule, target the lowest serum lithium level that is effective and prevent lithium intoxication. We emphasize the importance of monitoring for Li-NDI and Li-NP, as early diagnosis and treatment can prevent further progression and permanent damage. Collaboration between psychiatrist, nephrologist and patients themselves is essential. In patients with Li-NDI and/or Li-NP cessation of lithium therapy and/or switch to another mood stabilizer should be considered. In patients with Li-NDI, off label therapy with amiloride can be useful.

Genetic deletion of ADP-activated P2Y12 receptor ameliorates lithium-induced nephrogenic diabetes insipidus in mice.

AIM: Therapeutic use of lithium in bipolar disorder is limited by the development of nephrogenic diabetes insipidus (NDI). We reported that pharmacological blockade of P2Y12 receptor (R) with clopidogrel or prasugrel significantly ameliorated lithium-induced NDI in rodents. Using mice genetically lacking P2Y12 -R we evaluated whether the observed amelioration is mediated through P2Y12 -R METHODS: P2ry12-/- mouse line (C57/BL6) was rederived from cryopreserved embryos of the knockout (KO) mice generated by Deltagen Inc. Syngeneic wild type (WT) mice obtained by heterozygous crossing were inbred. Groups of adult WT and KO mice were fed lithium-added (40 mmol LiCl/kg food) or regular diet, and euthanized after 2 or 4 weeks. Twenty-four hour urine samples and terminal blood and kidney samples were analyzed. RESULTS: At both time points, lithium-induced polyuria and decrease in aquaporin-2 (AQP2) protein abundance in the kidney medulla were less marked in KO vs WT mice. Immunofluorescence microscopy revealed that lithium-induced alterations in the cellular disposition of AQP2 protein in the medullary collecting ducts of WT mice were blunted in KO mice. Serum lithium, sodium and osmolality were similar in both genotypes after lithium treatment. After 2 weeks, lithium induced marked increases in urinary excretion of Na, K, and arginine vasopressin in WT mice but not in KO mice. CONCLUSION: Taken together, our data show that similar to pharmacological blockade, deletion of P2Y12 -R significantly ameliorates lithium-induced NDI, without reducing serum lithium levels. Hence, targeting P2Y12 -R with currently available drugs in the market offers a novel and safer method for treating NDI.

Tamoxifen attenuates development of lithium-induced nephrogenic diabetes insipidus in rats.

Lithium is widely used in treatment of bipolar affective disorders but often causes nephrogenic diabetes insipidus (NDI), a disorder characterized by severe urinary-concentrating defects. Lithium-induced NDI is caused by lithium uptake by collecting duct principal cells and altered expression of aquaporin-2 (AQP2), which are essential for water reabsorption of tubular fluid in the collecting duct. Sex hormones have previously been shown to affect the regulation of AQP2, so we tested whether tamoxifen (TAM), a selective estrogen receptor modulator, would attenuate lithium-induced alterations on renal water homeostasis. Rats were treated for 14 days with lithium, and TAM treatment was initiated 1 wk after onset of lithium administration. Lithium treatment resulted in severe polyuria and reduced AQP2 expression, which were ameliorated by TAM. Consistent with this, TAM attenuated downregulation of AQP2 and increased phosphorylation of the cAMP-responsive element-binding protein, which induced AQP2 expression in freshly isolated inner-medullary collecting duct suspension prepared from lithium-treated rats. In conclusion, TAM attenuated polyuria dose dependently and impaired urine concentration and downregulation of AQP2 protein expression in rats with lithium-induced NDI. These findings suggest that TAM is likely to be a novel therapeutic option for lithium-induced NDI.

Amiloride modifies the progression of lithium-induced renal interstitial fibrosis.

AIM: Long-term administration of lithium has been associated with the development of a chronic interstitial fibrosis in addition to nephrogenic diabetes insipidus (NDI). Earlier studies have demonstrated that amiloride, by blocking the epithelial sodium channel ENaC and thus preventing lithium uptake into the principal cells of the collecting ducts, can partially reverse lithium-induced NDI. However, there are no long-term studies examining whether or not amiloride also modifies the progressive chronic interstitial fibrosis and tubular atrophy often evident with long-term lithium exposure. METHODS: Using an established animal model of lithium-induced chronic interstitial fibrosis, rats were treated with amiloride and lithium for 5 months following 1 month of exposure to lithium alone and compared with control animals and those given only lithium. RESULTS AND CONCLUSIONS: In this study, the 5 months of amiloride therapy partially mitigated the lithium-induced NDI and limited the further progression of lithium-induced kidney fibrosis. This improvement was associated with decreased expression of the pro-fibrotic connective tissue growth factor (CTGF), along with reduced myofibroblast infiltration and decreased collagen deposition around the distended cortical collecting ducts. This may, in part, be mediated by modifying lithium-induced alterations in ß-catenin activity through its effects on GSK-3ß.

The soluble (Pro) renin receptor does not influence lithium-induced diabetes insipidus but does provoke beiging of white adipose tissue in mice.

Earlier we reported that the recombinant soluble (pro) renin receptor sPRR-His upregulates renal aquoporin-2 (AQP2) expression, and attenuates polyuria associated with nephrogenic diabetes insipidus (NDI) induced by vasopressin type 2 receptor (V2R) antagonism. Patients that receive lithium therapy develop polyuria associated NDI that might be secondary to downregulation of renal AQP2. We hypothesized that sPRR-His attenuates indices of NDI associated with lithium treatment. Eight-week-old male C57/BL6 mice consumed chow supplemented with LiCl (40 mmol/kg diets) for 14 days. For the last 7 days mice received either sPRR-His [30 µg/(kg day), i.v.; sPRR] or vehicle (Veh) via minipump. Control (Con) mice consumed standard chow for 14 days. Compared to Con mice, 14-d LiCl treatment elevated water intake and urine volume, and decreased urine osmolality, regardless of sPRR-His or Veh administration. These data indicate that sPRR-His treatment does not attenuate indices of NDI evoked by lithium. Unexpectedly, epididymal fat mass was lower, adipocyte UCP1 mRNA and protein expression were higher, and multilocular lipid morphology was enhanced, in LiCl-fed mice treated with sPRR-His versus vehicle. The beiging of white adipose tissue is a novel metabolic benefit of manipulating the sPRR in the context of lithium-induced NDI.

Rapamycin inhibition of mTORC1 reverses lithium-induced proliferation of renal collecting duct cells.

Nephrogenic diabetes insipidus (NDI) is the most common renal side effect in patients undergoing lithium therapy for bipolar affective disorders. Approximately 2 million US patients take lithium of whom ∼50% will have altered renal function and develop NDI (2, 37). Lithium-induced NDI is a defect in the urinary concentrating mechanism. Lithium therapy also leads to proliferation and abundant renal cysts (microcysts), commonly in the collecting ducts of the cortico-medullary region. The mTOR pathway integrates nutrient and mitogen signals to control cell proliferation and cell growth (size) via the mTOR Complex 1 (mTORC1). To address our hypothesis that mTOR activation may be responsible for lithium-induced proliferation of collecting ducts, we fed mice lithium chronically and assessed mTORC1 signaling in the renal medulla. We demonstrate that mTOR signaling is activated in the renal collecting ducts of lithium-treated mice; lithium increased the phosphorylation of rS6 (Ser240/Ser244), p-TSC2 (Thr1462), and p-mTOR (Ser2448). Consistent with our hypothesis, treatment with rapamycin, an allosteric inhibitor of mTOR, reversed lithium-induced proliferation of medullary collecting duct cells and reduced levels of p-rS6 and p-mTOR. Medullary levels of p-GSK3ß were increased in the renal medullas of lithium-treated mice and remained elevated following rapamycin treatment. However, mTOR inhibition did not improve lithium-induced NDI and did not restore the expression of collecting duct proteins aquaporin-2 or UT-A1.

Nephrogenic diabetes insipidus secondary to syphilis infection.

CONTEXT: Nephrogenic diabetes insipidus (NDI) is caused by partial or complete renal resistance to the effects of antidiuretic hormone. Acquired NDI can be caused by electrolyte imbalances (eg, hypercalcemia), renal/extrarenal diseases (eg, chronic pyelonephritis), and drugs (eg, lithium toxicity). Syphilis has never been reported to cause NDI. OBJECTIVE: The aim of this study was to report the case of a 56-year-old man with NDI secondary to syphilis. CASE: The 56-year-old patient presented with polyuria and polydipsia lasting more than 40 days. His urine specific gravity was 1.002. He had no history of chronic kidney disease or contact with toxicants. He had normal blood glucose levels. A water-deprivation test and vasopressin administration indicated NDI. His rapid plasma reagin titer was 1:128. The serum Treponema pallidum-particle agglutination test was positive. He reported engaging in unprotected, extramarital sex 6 months before polydipsia onset and thereafter developing a skin lesion on the external genitalia and arthralgia, both of which resolved spontaneously. Examination of renal biopsy specimens showed abundant plasmacytic and lymphocytic infiltration of the interstitium and low and flat tubular epithelial cells, indicating renal tubular injury. Silver staining revealed T. pallidum-like organisms. Immunohistochemical analysis with T. pallidum-specific antibody confirmed the presence of treponemes. INTERVENTION: The patient received 2.4 million U of benzathine penicillin im once a week for 3 weeks. RESULTS: His urine output gradually reduced; he recovered 1 month later. His urine specific gravity was 1.026, and his syphilis rapid plasma reagin titer was 1:8. CONCLUSION: Syphilis can cause NDI. The manifestations of syphilis and causes of acquired NDI are diverse.

Vasopressin-independent targeting of aquaporin-2 by selective E-prostanoid receptor agonists alleviates nephrogenic diabetes insipidus.

In the kidney, the actions of vasopressin on its type-2 receptor (V2R) induce increased water reabsorption alongside polyphosphorylation and membrane targeting of the water channel aquaporin-2 (AQP2). Loss-of-function mutations in the V2R cause X-linked nephrogenic diabetes insipidus. Treatment of this condition would require bypassing the V2R to increase AQP2 membrane targeting, but currently no specific pharmacological therapy is available. The present study examined specific E-prostanoid receptors for this purpose. In vitro, prostaglandin E2 (PGE2) and selective agonists for the E-prostanoid receptors EP2 (butaprost) or EP4 (CAY10580) all increased trafficking and ser-264 phosphorylation of AQP2 in Madin-Darby canine kidney cells. Only PGE2 and butaprost increased cAMP and ser-269 phosphorylation of AQP2. Ex vivo, PGE2, butaprost, or CAY10580 increased AQP2 phosphorylation in isolated cortical tubules, whereas PGE2 and butaprost selectively increased AQP2 membrane accumulation in kidney slices. In vivo, a V2R antagonist caused a severe urinary concentrating defect in rats, which was greatly alleviated by treatment with butaprost. In conclusion, EP2 and EP4 agonists increase AQP2 phosphorylation and trafficking, likely through different signaling pathways. Furthermore, EP2 selective agonists can partially compensate for a nonfunctional V2R, providing a rationale for new treatment strategies for hereditary nephrogenic diabetes insipidus.

The perioperative challenge of nephrogenic diabetes insipidus: a multidisciplinary approach.

Nephrogenic Diabetes Insipidus (NDI) is characterised by the inability of the kidneys to concentrate urine in response to arginine vasopressin (AVP). Such patients typically experience polyuria and polydipsia because of this inability to autoregulate their water balance. This provides a perioperative challenge that could lead to a life-threatening situation. This article documents a patient with NDI who underwent an elective bowel re-anastomosis. Two peak serum sodium values were attained. The first when the patient was retaining sodium due to an inappropriate fluid regimen and the second due to hypovolaemia. The literature is reviewed and principles for NDI perioperative management are proposed.