The effects of age on the dopamine (DA) turnover and 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (6R-BH4), a cofactor for monooxygenases, were investigated in the striatum and midbrain of the senescence accelerated mouse (SAM) at 6, 12 and 15 months old. 6R-BH4 and DA levels were decreased significantly in the striatum of 15-month-old SAM-P/1 (senescence accelerated prone) mice. At 12 months old, DA level was decreased significantly in the striatum of SAM-P/1 compared with SAM-R/1 (senescence accelerated resistant) mice. The reduction of striatal DA level was shown to be related to the depletion of 6R-BH4 in the striatum during the processes of aging. Age-related decreases in striatal dopamine function occurred in SAM-P/1 mice earlier than in the SAM-R/1 mice. The striatal [DOPAC]/[DA] ratio, as the index of DA turnover, was increased significantly in the 15-month-old SAM-P/1 mice. On the other hand, the DA, 6R-BH4 levels and the ratio of [DOPAC]/[DA] did not show any changes in the midbrain of SAM-P/1 and SAM-R/1 during the processes of aging. It was suggested that brain vulnerability with aging may be associated with the levels of 6R-BH4.
The literature described that neural damage caused by ischemia definitely occurs in brain areas. However, few studies have shown real-time changes of extracellular monoamine levels at the time of transient ischemia.We examined changes in the responses of dopamine (DA) and serotonin (5-HT) release in the nucleus accumbens (ACC) of rats treated with four-vessel occlusion (4VO) in experiment 1. In the second experiment, we investigated the selective neural vulnerabilities among the ACC, lateral hypothalamus (LH), and frontal cortex (FC) of rats treated with 4VO and four days of reperfusion.The extracellular levels of DA and 5-HT were remarkably increased 200- and 20-fold upon the 10-min clipping of both common carotid arteries in transient cerebral ischemia, respectively. Each increased monoamine release returned to the baseline levels immediately. The release of DA in the ACC and FC was significantly decreased in the rats treated with the coagulation of bilateral vertebral arteries (2VO), compared with that of sham-operated rats. K(+)-induced DA release in the ACC and FC of 4VO-treated rats was increased without alteration of DA content.Surviving dopaminergic neurons in the ACC and FC showed neural hyperfunction associated with the monoamine release, serotonergic neurons in particular these areas exhibiting functional resistance to the transient ischemic change.It is suggested that the remarkable extracellular release of DA and 5-HT was not the cause of the ischemic delayed neural degeneration in each brain area, and that the functions of neurotransmitter release involved remarkable resistance to the transient ischemia.
6R-L-erythro-5,6,7,8-tetrahydrobiopterin (6R-BH4) is a coenzyme for tyro-sine, tryptophan and phenylalanine hydroxylases. Male C57BL/6J and DBA/ 2J mice were given 6R-BH4 (0,12.5, 25.0 and 50.0 mg/kg of body weight, i.v.) or saline, and then 4 h later, all animals were injected with ethanol (EtOH) (4.0 g/kg, i.p.), which causes them to lose the righting reflex, to investigate the differences in EtOH-induced sleeping time. 6R-BH4 pretreatment reduced EtOH-induced sleep time in DBA/2J mice with lower alcohol preference (p < 0.05), which showed no changes in the pharmacokinetics of blood EtOH. No changes in EtOH-induced sleep time were observed in C57BL/6J mice with higher alcohol preference. These results indicate that the sensitivity to EtOH in mice with lower alcohol preference was associated with 6R-BH4 activity in the CNS.
1. In the present study, we conducted the first randomized, double-blind, placebo-controlled study of bofu-tsusho-san (BF), an oriental herbal medicine (24 mg/day ephedrine in Ephedrae Herba and an efficacy equivalent of 280 mg caffeine, judging from the phosphodiesterase-inhibitory effect of Glycyrrhizae Radix, Forsythiae Fructus and Schizonepetae Spica and another 14 crude drugs) in obese women with impaired glucose tolerance (IGT). 2. The aim of the present study was to determine whether BF was effective in decreasing visceral adiposity and insulin resistance. Eighty-one Japanese women (body mass index (BMI) 36.5 ± 4.8 kg/m2) with IGT and insulin resistance (IR), who had been treated with a low-calorie diet (5016 kj/day: 1200 kcal) and an exercise regimen (1254 kj/day: 300 kcal), were randomized to receive either placebo (n = 40) or BF treatment (n = 41) three times a day. 3. After 24 weeks treatment, the BF group lost significantly (P < 0.01) more bodyweight and abdominal visceral fat without a decrease in the adjusted resting metabolic rate (RMR), whereas the placebo group lost bodyweight (P < 0.05) and had no significant change in abdominal visceral fat. The BF group had a lower fasting serum insulin level (P < 0.05), a lower insulin area under the curve (P < 0.05) and a lower level of the homeostasis model assessment of insulin resistance (P < 0.01) compared with values before treatment. 4. We conclude that BF could be a useful herbal medicine in treating obesity with IGT.
6R-L-erythro-5, 6, 7, 8-tetrahydrobiopterin (6R-BH4) is a coenzyme for tyrosine, tryptophan and phenylalanine hydroxylases, the former two of which are the initial and the rate-limiting enzymes in the biosynthesis of the catecholamines and serotonin, respectively. The present study was designed to determine the changes in concentrations of 6R-BH4 in striatum and midbrain of the inbred strains of mice, DBA/2J, C3H/HeJ and C57BL/6J, with different genetically determined alcohol preferences, following the injection of ethanol (EtOH). The intraperitoneal administration of EtOH (0, 1, 2 and 4 g/kg) significantly and dose-dependently reduced the levels of striatal and midbrain 6R-BH4 in DBA/2J mice with the lowest alcohol preference, and EtOH (4 g/kg, i.p.) reduced the level of striatal 6R-BH4 in C3H/HeJ with medium alcohol preference. Following the administration of EtOH (4 g/kg, i.p.), brain 6R-BH4 levels in C57BL/6J mice with high alcohol preference were lowered compared with the control group, but the difference did not reach statistic significance. EtOH has a tendency to reduce the brain 6R-BH4 levels in mice with lower alcohol preference or higher sensitivity to EtOH. Based on these findings, it was proposed that differences in alcohol drinking behavior in the inbred strains of mice was influenced by brain 6R-BH4.
SUMMARY 1. The anti‐obesity and anti‐diabetic effects of mazindol were evaluated in obese diabetic yellow KK mice and C57B1 control mice. 2. The study compound was fed through a gastric tube at a rate of 1 or 2 mg/kg per day (0.01 mol/L HC1 as control) for 2 weeks. The following parameters were compared in treated and control animals: bodyweight, food intake, white adipose tissue (WAT) weight, brown adipose tissue (BAT) weight and its thermogenesis, noradrenaline (NA) turnover, blood glucose and serum insulin levels and glucose transporter 4 (GLUT4). 3. Furthermore, bodyweight loss of mice pair‐fed the same amount of food as the mazindol‐treated mice for 2 weeks was measured. 4. Mazindol significantly decreased food intake and significantly increased guanosine‐5′‐diphosphate‐binding in BAT mitochondria and NA turnover in BAT in both yellow KK and C57B1 groups. The amounts of WAT in subcutaneous, mesenteric and retroperitoneal regions and bodyweights were significantly decreased in both groups. Bodyweight loss in mice pair fed with the mazindol‐treated groups was approximately 70% compared with that in the mazindol‐treated groups. Furthermore, mazindol decreased the levels of blood glucose and serum insulin during the glucose overloading test in yellow KK mice, but it did not influence the GLUT4 protein concentration in WAT and muscle. 5. These observations suggest that mazindol possesses both an anti‐obesity action, due to the inhibition of appetite as well as the activation of BAT thermogenesis via increased NA turnover in BAT, and an anti‐diabetic action. Consequently, mazindol may be useful for the treatment of obesity as well as non‐insulin‐dependent diabetes mellitus in obese persons.
Accumulating evidence in humans demonstrates that visuo-spatial deficits are the most consistently reported cognitive abnormalities in Parkinson's disease (PD). Ezrin, radixin, and moesin are collectively known as ERM proteins. Although ERM proteins have important implications in cell-shape determination and relevant signaling pathway, they have not been studied in the hippocampus in association with visuo-spatial memory impairments. The purpose of the present study is to examine whether the expression level of ERM proteins in the hippocampus is changed by an intrastriatal injection of 6-hydroxydopamine (6-OHDA) in mice. The intrastriatal injection of 6-OHDA induced partial dopaminergic deficits and spatial memory impairments. We also found that ezrin was increased in the hippocampus by the microinjection of 6-OHDA. On the other hand, protein levels of radixin and moesin were not influenced by 6-OHDA lesions. These results suggest that excessive ezrin may be related to visuo-spatial memory impairments.
