Uric acid (UA) is well known as the end product of purine metabolism in human. Hyperuricemia is defined as a serum UA level of ≥ 7.0 mg/dl (416 µM) in Japanese guideline for the management of ...hyperuricemia and gout (second edition), which is known as a risk factor for cardiovascular disease. Recently, it has been reported that low UA levels as well as high UA levels are predictive markers of increased mortality in epidemiologic studies. Hence, the aim of this study is to assess the role of UA at physiological concentration (conc) in normal cells. Normal human dermal fibroblasts were treated with UA conc at 62.5 - 500 µM (1.1 - 8.4 mg/dl). Cell viability of UA treated groups within the normal range was higher than that of control group. There was no change in cell number among groups, but total protein levels in UA treated groups increased at 72 hours. On the other hand, UA is known to have the potential antioxidant effects. Physiological conc of UA treatment decreased reactive oxygen species in the present study. Additionally, the expression of an oxidative stress-related protein was increased by UA treatment. Taken together, these findings suggest that physiological conc of UA in normal cells is probably implicated in cell viability.
Mammalian sperm, including human, must undergo several physiological and biochemical changes, collectively called capacitation, to be fertilization-competent. Capacitated sperm actively generate ...reactive oxygen species (ROS). A low level of ROS facilitates capacitation whereas an excessive ROS impairs capacitation. Hypotaurine (HT) is a precursor of taurine, and is abundant in the oviduct. HT is known to mitigate oxidative stress in hamster sperm, and is transported by taurine transporter (TauT) in a Na+- and Cl-- dependent manner. However, how HT protect sperm from oxidative stress remains unknown. This study aimed to elucidate the antioxidant mechanisms by HT in hamster sperm, focusing on the involvement of TauT. We first examined the effects of HT on sperm motility, intra- and extra- cellular ROS levels. HT was shown to be necessary to maintain motility. HT lowered intracellular ROS levels, but had no effect on extracellular ROS levels at the concentration tested, although HT itself has an antioxidative capacity at higher concentrations. Incorporation and enrichment of HT in sperm were confirmed by LC-MS/MS analysis. Next, the involvement of TauT was investigated. TauT was present in hamster sperm. β-alanine, a blocker of TauT, inhibited HT transport, increased intracellular ROS levels and impaired sperm motility. Moreover, the elimination of Na+ and Cl- inhibited HT transport, and increased intracellular ROS levels. In conclusions, the results indicate that hamster sperm incorporate and concentrate HT via TauT to protect themselves from ROS.
In order to investigate molecules related to insulin secretion, we conducted a practical method to imitate human insulin secretion through rats via organ baths of pancreatic preparations. Our ...previous study showed that insulin secretion from rat pancreas tissue was stimulated by glucagon-like peptide-1 and glimepiride. 1,5-anhydro-D-glucitol (1,5-AG) is a glucose analog and exists in humans. This study aims to assess the effects of short-term 1,5-AG stimulation of insulin secretion in rat pancreases to better understand the effects in humans. Rat pancreases were assigned to eight groups: two glucose concentrations (100 and 400 mg/dl) and pairs of varying 1,5-AG concentrations (0, 0.1, 1, and 10 mM). There was a significant increase in insulin outflow from low to high glucose concentrations. However, there was no significant enhancement of insulin secretion between the four groups with low and high 1,5-AG concentrations. This suggests that short-term exposure to 1,5-AG has no effect on insulin secretion in rat pancreas tissues. To justify whether the methods and techniques were useful as an experimental system, we isolated pancreases from another rodent species, the mouse, and similarly measured insulin outflow. In mouse pancreas preparations, stimulating with 400 mg/dl glucose significantly increased insulin outflow. Therefore, organ baths of isolated mouse pancreases are also considerably effective for assessing effects of novel molecules and/or therapeutics on insulin secretion.
Due to the coronavirus pandemic situation, the pharmacological role-playing was conducted by online in 2020 and 2021. We reported consideration of pros and cons of the online pharmacology ...role-playing from results of a two-year student questionnaire survey. Two hundred twenty five 3rd-grade medical students joined the role-playing at Dokkyo Medical University. Twenty-four students were assigned as physicians or patients and played the informed consent in two cases; hypertension accompanying diabetes and dementia with polypharmacy. The remaining students were observers. All students answered the questionnaire with a score of one to five, regarding the usefulness of study on disease and pharmacotherapy, understanding the patients' feeling, improvement of motivation to become a doctor, and change of attitude to studying. The percentage of students who scored five or four was 63 to 83% for the players and 71 to 80% for the observers. The frequent answers regarding necessary points of the study were "quality of the study" and "communication ability" and "perspective from the patients" for the players, and "communication ability", "quality of the study" and "perspective from the patients" for the observers in order of frequency. Most students described positive impression in the free entry field that was considered as pons. A description of the difficulty of adjusting the online settings was considered as cons. Online pharmacological role-playing may be a useful approach for the medical students to learn the pharmacotherapy and doctor-patient relationship.
It is well known that glucagon-like peptide 1 (GLP-1) can bind to the GLP-1 receptor of pancreatic islet to enhance insulin secretion through a cAMP-dependent pathway. However, little is known about ...the effects of GLP-1 on the pancreatic exocrine gland. In the gland, a signal transduction of amylase release is evoked mainly by an increase in intracellular Ca2+ levels and activation of PKC. Myristoylated alanine-rich C kinase substrate (MARCKS) is known as a major substrate for PKC. We previously demonstrated that MARCKS is involved in pancreatic amylase release through the Ca2+-dependent pathway. Here, we studied the effects of GLP-1 on MARCKS phosphorylation and amylase release through the cAMP-dependent pathway in rat pancreatic acini. By the organ bath technique, GLP-1 did not induce amylase release in the intact pancreas. In contrast, it induced amylase release and MARCKS phosphorylation in isolated pancreatic acini. An inhibitor of PKA suppressed those effects. Furthermore, a MARCKS-related peptide inhibited the GLP-1-induced amylase release. These findings suggest that GLP-1 induces amylase release through MARCKS phosphorylation via activation of PKA in the isolated acini, but not in the intact pancreas.
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