Activation of the mTOR dependent signaling pathway underlies ketamine-induced uropathy

Ketamine-Induced Cystitis: A Comprehensive Review of the Urologic Effects of This Psychoactive Drug

Ketamine is a common medical anesthetic and analgesic but is becoming more widely used as a recreational drug. Significant side effects on the urinary tract are associated with frequent recreational ketamine use most notably ketamine-induced cystitis (KIC). Regular ketamine consumption has been shown to increase the risk of cystitis symptoms by 3- to 4-fold, and cessation of ketamine use is usually associated with improvement of symptoms. Common KIC-related problems are urinary pain and discomfort, bladder epithelial barrier damage, reduced bladder storage and increased pressure, ureter stenosis, and kidney failure, all of which significantly impact patients' quality of life. Furthermore, it becomes a vicious cycle when KIC patients attempt to manage their urinary pain with increased ketamine use. The precise pathophysiology of KIC is still unknown but several theories exist, most of which highlight the inflammatory signaling pathways leading to bladder epithelium damage due to presence of ketamine in the urine. Empirical treatment options for KIC are available and consist of ketamine cessation, noninvasive therapies, and surgery, and should be decided upon based on the time course and severity of the disease. Of note, cessation of use is strongly recommended for all KIC patients, and should be supplemented with motivational interviews and psychological and social support. It is crucial for clinicians to be familiar with KIC diagnosis and treatment, and to be prepared to have informed discussions with ketamine-using patients about the potential health consequences of ketamine.

(2R,6R)-Hydroxynorketamine Alleviates Electroconvulsive Shock-Induced Learning Impairment by Inhibiting Autophagy

PURPOSE

Learning impairment after electroconvulsive therapy (ECT) is common. Ketamine, an anesthetic used for ECT, has been demonstrated to attenuate cognitive impairment after ECT. However, the mechanism by which ketamine occurs in this case is still unknown. We aimed to explore the role of ketamine metabolite (2R,6R)-hydroxynorketamine [(2R,6R)-HNK] in the protection against learning impairment and investigate whether autophagy is involved in the protective effect.

MATERIALS AND METHODS

A rat depression model received electroconvulsive shock (ECS; simulated ECT in animal models) daily for 3 days. The Morris water maze was used to assess the spatial learning function of the rats. Western blotting was used to detect the expression of Beclin-1, light chain (LC)3-II/LC3-I, p62, mammalian target of rapamycin (mTOR), and p-mTOR in the hippocampus.

RESULTS

The escape latency for the maze in the ECS group was significantly longer than that in the sham ECS group (P=0.042). Meanwhile, the escape latency in the (2R,6R)-HNK+ECS group was significantly shorter than that in the ECS group (P=0.005). The LC3-II/LC3-I ratio and Beclin-1 expression level significantly increased, and the p62 expression level significantly decreased in the ECS group, compared with those in the sham ECS group (all P<0.001). The (2R,6R)-HNK+ECS group showed lower LC3-II/LC3-I ratio (P<0.001) and Beclin-1 expression level (P<0.001) and higher p62 (P<0.001) and p-mTOR expression levels (P=0.048) than did the ECS group. After small-molecule enhancer of rapamycin 28 (SMER28) administration, the role of (2R,6R)-HNK in protecting against learning impairment and inhibiting autophagy was abrogated, showing no difference in the escape latency; the difference in the LC3-II/LC3-I ratio and p62 expression level between the SMER28+(2R,6R)-HNK+ECS and ECS groups was not as significant as that between the (2R,6R)-HNK+ECS and ECS groups (P<0.05-0.01 vs P<0.001).

CONCLUSION

(2R,6R)-HNK yields cognitive protection by suppressing autophagy through the mTOR signaling pathway in the ECS-treated rat hippocampus.

Mechanisms of Inhibition of Excessive Microglial Activation by Melatonin

As the innate immune cells that permanently reside in the central nervous system (CNS), microglia play an increasingly important role in maintaining brain function. Normally, microglia act as resting phenotype, which can be activated by various types of stimuli and release a variety of inflammatory mediators. Melatonin is an endogenous rhythmic hormone secreted principally by the pineal gland. Increasing evidence suggests that melatonin can detoxify reactive oxygen species (ROS) and prevent microglia from over-activation. This review summarizes the mechanisms of melatonin in inhibiting excessive activation of microglia and demonstrates the feasibility of melatonin in the treatment of diseases related to microglial over-activation.

Recent advances in imaging and understanding interstitial cystitis

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating condition associated with intense pelvic pain and bladder storage symptoms. Since diagnosis is difficult, prevalence estimates vary with the methodology used. There is also a lack of proven imaging tools and biomarkers to assist in differentiation of IC/BPS from other urinary disorders (overactive bladder, vulvodynia, endometriosis, and prostatitis). Current uncertainty regarding the etiology and pathology of IC/BPS ultimately impacts its timely and successful treatment, as well as hampers future drug development. This review will cover recent developments in imaging methods, such as magnetic resonance imaging, that advance the understanding of IC/BPS and guide drug development.