The present study investigated the cellular mechanism underlying the degradation of heme oxygenase-1 (HO-1), an endoplasmic reticulum (ER)-anchored protein. The turnover of HO-1 induced in vascular smooth muscle cells (VSMCs) was significantly attenuated by proteasome inhibitors, suggesting the involvement of a proteasome-mediated pathway. High molecular weight ubiquitin conjugates were co-immunoprecipitated with HO-1 from VSMCs after proteasome inhibition, and HO-1 ubiquitination was confirmed in HEK293 cells overexpressing His-tagged HO-1 and HA-tagged ubiquitin. Endogenous p97, an ATPase, and Ufd1, both implicated as essential components in the ER-associated degradation pathway (ERAD), were co-eluted with His-tagged HO-1 from metal affinity resin. Knockdown of either p97 or Ufd1 in HEK293 cells using specific siRNA significantly prolonged the half-life of endogenously induced HO-1 and slowed the degradation of ubiquitinated HO-1. HO-1 ubiquitination in HEK293 cells was enhanced by zinc chloride, but suppressed with a zinc chelator (N,N,N',N'-tetrakis(2-pyridylmethyl)ethyl-enediamine), suggesting the involvement of a RING-E3 ligase in this process. Collectively, these data indicate that HO-1 protein turnover is regulated by the ubiquitin-proteasome system through the ERAD pathway.

Chronic amphetamine intake leads to neurogenic bladder and chronic urinary retention. The mechanism underlying persistent urinary retention is unclear. The pelvic-urethral reflex (PUR) is essential for the urethra to develop sufficient resistance to maintain urine continence, an important function of the urinary system. Recent studies on PUR activities have indicated that repetitive/tetanic stimulation of the pelvic afferent fibers induces spinal reflex potentiation (SRP) in PUR activities, which further increases urinary retention. In this study, results showed that test stimulation (TS, 1/30 Hz) evoked a baseline reflex activity, while repetitive stimulation (RS, 1 Hz) induced reflex potentiation in the external urethral sphincter. Intrathecal d-amphetamine (AMPH, 30 μM) did not but higher AMPH concentration (100 μM) induced SRP in TS-induced reflex activity. H89 (10 μM, a protein kinase A inhibitor), but not chelerythrine chloride (CTC, 10 μM, a protein kinase C inhibitor), prevented the 100 μM AMPH-elicited SRP. At 30 μM, forskolin, an activator of adenylyl cyclase, elicited SRP. The co-administration of 10 μM forskolin and 30 μM AMPH induced SRP in TS-induced reflex activity. These results implied that the repetitive/tetanic stimulation of the pelvic afferent fibers could induce SRP in PUR activities, so that the urethra can produce sufficient resistance and played a significant role in urinary retention. Findings in this study demonstrated that amphetamine could induce bladder dysfunction by triggering protein kinase A activation, and provide a practical basis for the development of treatment for amphetamine-associated urinary retention.

Aging is accompanied by changes in organ degeneration, and susceptibility to multiple diseases, leading to the frequent occurrence of adverse drug reactions resulting from polypharmacy (PP) and potentially inappropriate medications (PIM) in older patients. This study employs a retrospective cohort design and investigates the association of PP with PIM among older patients with high rates of medical utilization. Using records from a national pharmaceutical care database, an experimental group is formed from patients meeting these criteria, who are then offered home pharmaceutical care. Correspondingly, a control group is formed by identifying older patients with regular levels of use of medical services who had been dispensed medications at community pharmacies. Multivariate logistic regression is performed to assess the association between the rate of PIM and variables, including age, gender, and PP. The study finds that experimental PP participants had a higher rate of PIM prescription (odds ratio (OR) = 5.4) than non-PP control participants (all p < 0.001). In clinical practice, additional caution is required to avoid PIMs. Patients engaged in continuously using long-term medication should take precautions in daily life to alleviate related discomforts. Pharmacists should serve as a bridge between patients and physicians to enhance their health and improve their quality of life.