Effect of chronic forced running on gene expression of catecholamine biosynthetic enzymes in stellate ganglia of rats.

The sympathoneural system has a profound influence on the heart function. Sympathetic neurons are the major contributors to the huge rise of circulating noradrenaline (NA) level in response to stressful stimuli. Treadmill training in rats is forced exercise which has the propensity to induce both psychological and physical stress. The aim of this study is to examine how chronic forced running (CFR) affects the expression of catecholamine biosynthetic enzymes (tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT)) and cAMP response element-binding (CREB) in stellate ganglia, as well as the concentrations of catecholamines, adrenocorticotropic hormone (ACTH) and corticosterone (CORT) in the plasma of rats. Also, we investigated how the additional acute immobilization stress changes the mentioned parameters. The rat training program consisted of 12 weeks running on a treadmill (20 m/min, 20 min/day). We found that CFR increases TH and DBH mRNA and protein levels in stellate ganglia, which is followed by increased NA concentration in the plasma. CFR reduces the level of PNMT mRNA, while the level of PNMT protein remains unchanged in stellate ganglia. The increased expression of TH and DBH genes positively correlates with the expression of CREB in stellate ganglia and with plasma ACTH level, while reduced level of PNMT mRNA in stellate ganglia correlates with reduced plasma CORT level. The additional acute immobilization stress increased gene expression of catecholamine biosynthetic enzymes in stellate ganglia, as well as catecholamines, ACTH and CORT levels in the plasma. The results presented here suggest that the continuous increase of the noradrenaline biosynthetic enzyme expression in stellate ganglia due to CFR may play a role in growing risk of cardiovascular diseases.

Systolic right ventricular adaptive changes in athletes as predictors of the maximal functional capacity: a pulsed tissue Doppler study.

AIM: The aim of this study was to extend the analysis of the systolic right ventricular (RV) adaptation to combined endurance and strength training, to assess the utility of tissue Doppler imaging in detecting the degree of these changes and to find independent RV predictors of the maximal functional capacity. METHODS: Standard Doppler and TDI were used to assess cardiac parameters at rest in 37 elite male athletes (16 wrestlers, 21 water polo players) and 20 sedentary subjects of similar age. Progressive maximal test on treadmill was used to assess VO2max. The obtained parameters were adjusted for HR, FFM, and BSA. RESULTS: Wrestlers showed higher VO2max than controls, but lesser than water polo players. RV diameter was larger in athletes. Right atrial pressure (RVE/e) was higher in water polo players than in other groups. Systolic function assessed by tricuspid annular plane systolic excursion (TAPSE) and RVs' was the highest in wrestlers. Global RV systolic parameters myocardial performance index (MPI) and preejection time/ejection time index (PET/ET) were similar. On multivariate analysis systolic parameters were independent predictors of VO2max only in wrestlers: RVs' (beta=3.18, P=0.001) and RV ET (beta=2.32, P=0.001). RVE/e` correlated with RVs' (r=-0.57, P=0.000). TAPSE correlated with RV ET (r=0.32, P=0.015) and RVs` (beta=0.28, P=0.033). CONCLUSION: Systolic function assessed by TAPSE and RVs` has more improved in less endurance athletes. RVs`and TDI ejection time predict VO2max in wrestlers, and possibly in other athletes with lesser right atrial pressure. TDI enables quantifying RV adaptation degree in athletes, but complementary to M-mode technique.

Sex differences in the sensitivity of CBA mice to convulsions induced by GABA antagonists are age-dependent.

The administration of the GABA-blocking agents picrotoxin and bicuculline to adult (2.5-3 months old) CBA/HZgr mice resulted in the appearance of convulsions, the occurrence and/or lethality of which was greater in males than in females. The latency of picrotoxin-induced convulsions was also shorter in male mice. Strychnine, a drug which induces convulsions by blocking glycine receptors was equally effective in producing convulsions in both male and female adult mice. Unlike adult mice, young (20 days old) or old (2 years old) mice fail to display sex differences following the picrotoxin administration. Accordingly, the observed sex differences in the sensitivity of CBA mice to administration of convulsive agents are specific for the GABA system and present only in sexually mature, but not in immature or old animals.

Urinary PC-1 and N-acetyl-beta-D-glucosaminidase activity in patients with type 2 diabetes treated with metformin, gliclazide or glibenclamide.

BACKGROUND: Insulin resistance is a key feature of type 2 diabetes mellitus. Plasma cell differentiation antigen (PC-1) is an inhibitor of insulin receptor tyrosine kinase, and has been implicated in the pathogenesis of insulin resistance. METHODS: Urinary excretion of PC-1 was determined in 45 newly detected, obese diabetic patients treated with metformin (16 patients), gliclazide (14 patients) or glibenclamide (15 patients). Urinary N-acetyl-beta-D-glucosaminidase (NAGA), a lysosomal enzyme, was determined as a marker of tubular damage in diabetes. RESULTS: Basal urinary PC-1 excretion in all three groups of diabetic patients was at the level of healthy controls. Treatment with oral hypoglycaemic drugs did not change significantly the group level or the number of patients in each group with increased PC-1 activity. Urinary excretion of NAGA in patients with type 2 diabetes was not statistically different from the control level. Metformin and gliclazide treatment did not change significantly the group levels of NAGA excretion. However, glibenclamide treatment produced an increased urinary NAGA excretion in the whole group, and in about twice as many patients as in the pre-treatment period.

Urinary PC-1 activity in patients with type 1 diabetes mellitus.

BACKGROUND: Insulin resistance characterizes type 1 diabetes mellitus with nephropathy. The molecular mechanisms of insulin resistance are not completely understood. Recently some advances have been made in identification of transmembrane glycoprotein PC-1 as a potential factor of insulin resistance. METHODS: We measured urinary excretion of PC-1 (alkaline phosphodiesterase I), a potential factor of insulin resistance, and N-acetyl-beta-D-glucosaminidase (NAGA) in 62 type 1 diabetic patients with different damage to the kidney. RESULTS: In newly detected type 1 diabetes patients, before insulin therapy, urine PC-1 excretion was significantly increased (P<0.05) over the control level. However, in patients after 12.4 years of therapy, urinary PC-1 was significantly decreased (P<0.05). Decreased urine PC-1 activity (P<0.05) was found also in type 1 diabetes patients with microalbuminuria and manifest nephropathy, including those with renal failure. Urinary NAGA excretion was found to be significantly increased (P=0.001) in all but the group of type 1 diabetes patients without nephropathy. CONCLUSION: This study of urinary PC-1 in patients with type 1 diabetes shows increased excretion in newly detected patients with poor glycaemic control, but decreased excretion in patients with micro-/macroalbuminuria as well as in those without apparent kidney damage. In patients with primary glomerulonephritis, urinary excretion of PC-1 was significantly decreased and that of NAGA significantly increased compared with the excretion in healthy controls.