Ketamine abusers develop severe lower urinary tract symptoms. The major aims of the present study were to elucidate ketamine-induced ulcerative cystitis and bladder apoptosis in association with oxidative stress mediated by mitochondria and the endoplasmic reticulum (ER). Sprague-Dawley rats were distributed into three different groups, which received normal saline or ketamine for a period of 14 or 28 days, respectively. Double-labeled immunofluorescence experiments were performed to investigate tight junction proteins for urothelial barrier functions. A TUNEL assay was performed to evaluate the distribution of apoptotic cells. Western blot analysis was carried out to examine the expressions of urothelial tight junction proteins, ER stress markers, and apoptosis-associated proteins. Antioxidant enzymes, including SOD and catalase, were investigated by real-time PCR and immunofluorescence experiments. Ketamine-treated rats were found to display bladder hyperactivity. This bladder dysfunction was accompanied by disruptions of epithelial cadherin- and tight junction-associated proteins as well as increases in the expressions of apoptosis-associated proteins, which displayed features of mitochondria-dependent apoptotic signals and ER stress markers. Meanwhile, expressions of mitochondria respiratory subunit enzymes were significantly increased in ketamine-treated bladders. Conversely, mRNA expressions of the antioxidant enzymes Mn-SOD (SOD2), Cu/Zn-SOD (SOD1), and catalase were decreased after 28 days of ketamine treatment. These results demonstrate that ketamine enhanced the generation of oxidative stress mediated by mitochondria- and ER-dependent pathways and consequently contributed to bladder apoptosis and urothelial lining defects. Such oxidative stress-enhanced bladder cell apoptosis and urothelial barrier defects are potential factors that may play a crucial role in bladder overactivity and ulceration.

Ketamine-induced ulcerative cystitis (KIC) initially damaged the bladder mucosa and induced contracted bladder thereafter. Hyaluronan (hyaluronic acid; HA) instillation to the bladder has been used to treat KIC. The present study investigated bladder injury by urothelial defect and HA degeneration and bladder repair by urothelium proliferation and differentiation. This work was based on the hypothesis that HA treatment altered the bladder urothelial layer and the expression of hyaluronan-metabolizing enzymes and/or HA receptors in KIC. Cystometrogram study and tracing analysis of voiding behavior revealed that the ketamine-treated rats exhibited significant bladder hyperactivity with an increase in micturition frequency and a decrease in bladder capacity. The expression of inflammatory and fibrosis markers was also increased in the ketamine-treated group. Moreover, ketamine administration decreased the expression of urothelial barrier-associated protein, altered HA production, and induced abnormal urothelial differentiation, which might attribute to urothelial lining defects. However, HA instillation ameliorated bladder hyperactivity, lessened bladder mucosa damage, and decreased interstitial fibrosis. HA instillation also improved the level of HA receptors (CD44, Toll-like receptor-4, and receptor for HA-mediated motility) and HA synthases 1 to 3 and decreased the expression of hyaluronidases in the urothelial layer of bladder, resulting in enhanced mucosal regeneration. These findings suggested that HA could modulate inflammatory responses, enhance mucosal regeneration, and improve urothelial lining defects in KIC.

Background Cluster headache is a highly debilitating neurological disorder with considerable inter-ethnic differences. Genome-wide association studies (GWAS) recently identified replicable genomic loci for cluster headache in Europeans, but the genetic underpinnings for cluster headache in Asians remain unclear. The objective of this study is to investigate the genetic architecture and susceptibility loci of cluster headache in Han Chinese resided in Taiwan. Methods We conducted a two-stage genome-wide association study in a Taiwanese cohort enrolled from 2007 through 2022 to identify the genetic variants associated with cluster headache. Diagnosis of cluster headache was retrospectively ascertained with the criteria of International Classification of Headache Disorders, third edition. Control subjects were enrolled from the Taiwan Biobank. Genotyping was conducted with the Axiom Genome-Wide Array TWB chip, followed by whole genome imputation. A polygenic risk score was developed to differentiate patients from controls. Downstream analyses including gene-set and tissue enrichment, linkage disequilibrium score regression, and pathway analyses were performed. Results We enrolled 734 patients with cluster headache and 9,846 population-based controls. We identified three replicable loci, with the lead SNPs being rs1556780 in CAPN2 (odds ratio = 1.59, 95% CI 1.42‒1.78, p = 7.61 × 10–16), rs10188640 in MERTK (odds ratio = 1.52, 95% CI 1.33‒1.73, p = 8.58 × 10–13), and rs13028839 in STAB2 (odds ratio = 0.63, 95% CI 0.52‒0.78, p = 2.81 × 10–8), with the latter two replicating the findings in European populations. Several previously reported genes also showed significant associations with cluster headache in our samples. Polygenic risk score differentiated patients from controls with an area under the receiver operating characteristic curve of 0.77. Downstream analyses implicated circadian regulation and immunological processes in the pathogenesis of cluster headache. Conclusions This study revealed the genetic architecture and novel susceptible loci of cluster headache in Han Chinese residing in Taiwan. Our findings support the common genetic contributions of cluster headache across ethnicities and provide novel mechanistic insights into the pathogenesis of cluster headache.