Metformin mitigates the impaired development of skeletal muscle in the offspring of obese mice.

BACKGROUND: Maternal obesity is linked with offspring obesity and type 2 diabetes. Skeletal muscle (SM) insulin resistance is central to the development of diabetes. Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is inhibited in SM of fetuses born to obese mothers. OBJECTIVE: The aim of this study was to evaluate the effect of maternal metformin administration on AMPK activity and reversion of adverse changes in offspring SM of obese mice. DESIGN: Female weanling C57BL/6J mice received either control diet (CON, 6 mice) or high-fat diet (HFD; OB, 12 mice) for 8 weeks before mating. After mating, mice continued receiving their respective CON or OB diets. In addition, 6 of those 12 mice fed with fat diet also received metformin administration (2 mg per ml in drinking water) throughout gestation and lactation (MET). After weaning at postnatal 21 days, offspring were fed a HFD to mimic a postnatal obesogenic environment until necropsy. RESULTS: Mothers receiving the fat diet developed obesity. OB offspring showed higher adiposity than CON and MET offspring. AMPK phosphorylation was lower in SM of OB offspring. ß-Catenin and myogenic regulatory factors, MyoD and myogenin, were downregulated in OB muscle, whereas the adipogenic marker, peroxisome proliferator-activated receptor-γ, was upregulated compared with CON muscle. Metformin administration prevented these changes in OB offspring SM. OB but not MET offspring demonstrated glucose intolerance. Mitochondrial content decreased, and activities of citrate synthase and ß-hydroxyacyl-CoA dehydrogenase also decreased in OB offspring SM, whereas they were recovered in MET offspring SM. CONCLUSION: Maternal metformin administration improves SM development in OB offspring.

Nutrition during mid to late gestation affects growth, adipose tissue deposition, and tenderness in cross-bred beef steers.

The objective of this study was to examine whether the plane of nutrition of cows at a critical time for fetal skeletal muscle and adipose tissue development would affect meat quality and carcass composition of offspring. To alter maternal nutrition, beef cows were placed on improved pasture (IP) or native range (NR) pasture from 120 to 150 through 180 to 210days of gestation. Esophageal extrusa samples collected from cows grazing IP varied from 11.1% crude protein of organic matter early in the test period to 6.0% crude protein of organic matter at the end of the grazing period; whereas, extrusa samples of cows grazing NR ranged from 6.5% crude protein of organic matter during early grazing to 5.4% crude protein of organic matter at the end of the grazing period. Steers were slaughtered and carcass characteristics were collected. Warner-Bratzler shear force was performed on longissumus steaks, western blotting was used to measure proteolysis, and myosin isoform typing was performed. Improved pasture steers had heavier live and hot carcass weights. Tenderness was greater in IP compared to NR steers. No difference in calpastatin content and troponin-T degradation was observed between treatments. The 12th rib fat thickness was greater for IP than for NR steers. Subcutaneous adipose tissue of IP steers tended to have a greater number of cells per field of view than NR steers. Data show improving nutritional status of cows during mid to late gestation affects tenderness, adipose tissue deposition and growth in steers.

Mouse AMP-activated protein kinase gamma3 subunit R225Q mutation affecting mouse growth performance when fed a high-energy diet.

The Rendement Napole (RN) genotype widely exists in Hampshire pigs. Recently, RN gene was identified as a R200Q mutation in AMP-activated protein kinase (AMPK) gamma3 subunit. The effect of RN genotype on the growth performance of animals and the underlying mechanisms remain controversial. Using transgenic mice carrying an analogous R225Q mutation, the objective of this study was to study the role of RN gene in the growth performance of animals at different energy levels. Wild-type (WT) mice and those with the RN mutation were assigned to 4 groups: 1) WT plus normal diet, 2) RN plus normal diet, 3) WT plus high-energy diet, and 4) RN plus high-energy diet. Mice were weaned at 21 d old and fed the trial diets for 1 mo and then killed for carcass measurements. The pH of postmortem muscle from RN mice was less (P < 0.01) than that from WT mice. No difference in growth performance was observed when mice were fed a normal diet. When fed a high-energy diet, RN mice showed a greater fat accumulation (WT vs. RN, 1.11 vs. 1.63 g for gonadal fat and 1.40 vs. 1.84 g for subcutaneous fat; P < 0.05). Muscle weight was also increased (WT vs. RN, 0.27 vs. 0.30 g for gastrocnemius muscle; P < 0.05). The food consumption was greater in RN compared with WT mice (2.95 vs. 2.49 g; P < 0.05). The AMPK content and its downstream target, acetyl-CoA carboxylase (ACC), content were greater in RN mice (P < 0.05). The phosphorylation of ACC at Ser 79, a site exclusively phosphorylated by AMPK, was increased (P < 0.05), showing greater AMPK activity in RN mouse muscle. No difference in muscle fiber composition and mitochondrial content was observed between WT and RN mice. High fat diet downregulates protein kinase B but upregulates extracellular signal-regulated kinase signaling. In conclusion, the R225Q mutation has no major effect on the growth performance of animals fed a normal diet; a high-energy diet increased fatness in RN mice, likely due to their greater consumption of feed compared with WT mice.

Fibrinolytic characteristics and their significance in malignant, tuberculous and cirrhotic pleural and ascitic fluids.

The fibrinolytic characteristics and clinical pathological significance of pleural and ascitic fluid were studied in patients with malignant tumour, tuberculosis or liver cirrhosis. Urokinase plasminogen activator (uPA) and urokinase plaminogen activator receptor (uPAR) levels were measured by enzyme-linked immunoadsorbent assay and tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), plasminogen (Plg), plasmin (Pl) and alpha(2) plasmin inhibitor (alpha(2)PI) by colorimetric assay. uPA and uPAR levels were higher in malignant tumour and tuberculosis compared with liver cirrhosis, whereas tPA levels were significantly higher in liver cirrhosis and malignant tumour than in tuberculosis patients. Tuberculosis patients showed statistically higher PAI-1, Plg and Pl concentrations than malignant tumour patients, which, in turn, were higher than those in liver cirrhosis patients. alpha(2)PI levels were markedly higher in malignant tumour and liver cirrhosis than in tuberculosis. In the malignant tumour group, only uPA level was significantly different between the samples that contained cancer cells and those that did not. We found significant differences between the fibrinolytic characteristics in pleural and ascitic fluid in patients with malignant tumour, tuberculosis and liver cirrhosis. The analysis of several fibrinolytic parameters could help to determine the quality of pleural and ascitic fluid, and also to further understand the pathological processes of these diseases.

Nerve fibers containing dynorphin A in cerebral arteries.

Nerve fibers containing dynorphin (Dyn) A(1-17)-like immunoreactivity were identified around cerebral arteries of guinea pig. The immunoreactive nerve fibers were richly distributed in anterior and middle cerebral arteries, but sparsely in posterior cerebral and basilar arteries. Histofluorescent study showed that large and small cerebral arteries were abundantly innervated by monoamine nerve fibers. Pretreatment with 6-hydroxydopamine or reserpine reduced the concentration of Dyn A in the wall of arteries by about 60% and 30%, respectively. These results demonstrated that there exist Dyn A immunoreactive nerve fibers in cerebral arteries and Dyn A may coexist with monoamine in perivascular nerve fibers.

[Effects of phencyclidine on rabbit basilar artery in vitro and rabbit cerebral blood flow in vivo].

The effect of phencyclidine [1-(1-phenylcyclohexyl)piperidine, PCP] on rabbit basilar arteries was studied with an in vitro model of ring segment arteries. PCP 0.05-500 mumol.L-1 caused vasoconstriction of basilar arteries in a concentration-dependent manner. Its maximal effect (Emax) was 94 +/- 21 mg and the concentration causing half maximal effect (EC50) was 25 +/- 18 mumol.L-1. PCP 0.01-10 mumol.L-1 also concentration-dependently augmented the vasoconstriction induced by electric stimulation in rabbit basilar arteries. Its Emax was 91 +/- 18 mg and EC50 was 0.27 +/- 0.17 mumol.L-1. The effects of PCP on mean arterial blood pressure (MABP) and heart rate (HR) of rabbits were observed. PCP iv 4 mg.kg-1 reduced MABP from 14.3 +/- 0.8 to 12.2 +/- 1.0 kPa and HR from 300 +/- 0 to 278 +/- 5 bpm in 5 min. Using the technique of radionuclide imaging in rabbit brain in vivo, we studied the effect of PCP on cerebral blood flow. After iv PCP 4 mg.kg-1, the tp of radiocerebrogram was increased from 4.5 +/- 1.1 to 6.1 +/- 1.0 s, the tg of radiocerebrogram was increased from 11.7 +/- 0.6 to 18.2 +/- 3.3 s and the rate of clearance was decreased. After iv PCP 2 mg.kg-1, only tg increased from 12.6 +/- 2.1 to 15.9 +/- 0.6 s. Hence PCP increased the transit time of nondiffusible indicators (99mTc) through the cerebral circulation. These results suggest that PCP causes constriction of basilar artery and slows down the cerebral blood flow.

[Antagonistic effect of phencyclidine on cerebral ischemic damage of rats].

Dynorphin and catecholamine were measured in ischemic rat produced by four-vessel (2 vertebral arteries and 2 common carotid arteries) occlusion for 10 min. The results showed that: (1) The contents of dynorphine (pg/mg tissue) in cerebral cortex were 5.5 +/- 0.6 (n = 7) in normal rats and decreased to 4.9 +/- 0.5 (n = 9, P less than 0.05) in cerebral ischemic rats; with immediate ip phencyclidine (1-(1-phenylcyclophexyl)piperidine, PCP, 1 mg.kg-1), the contents of dynorphin were increased to 5.3 +/- 0.4 (n = 5, P less than 0.05 vs the ischemic rats). (2) The contents of DOPAC (pg/mg tissue) in cerebral cortex were 38 +/- 6 (n = 7) and increased to 120 +/- 60 (n = 5, P less than 0.05) in 10 min cerebral ischemic rats; with immediately ip PCP (1 mg.kg-1), the contents of DOPAC were decreased to 26 +/- 13 (n = 7, P less than 0.05 vs the ischemic rats). (3) The release of DA (pg/mg tissue) in cortical slices in vitro, in high K+ solution were 24 +/- 3 (n = 5) and significantly increased to 57 +/- 15 (n = 5, P less than 0.05) in ischemic rat brain slices; with immediate ip PCP (1 mg.kg-1), the contents of DA were decreased to 38 +/- 10 (n = 5, P less than 0.05 vs the ischemic rats). These results suggest PCP play an antagonistic role in cerebral ischemic damage of rats.