Effects of whey protein on skeletal muscle microvascular and mitochondrial plasticity following 10 weeks of exercise training in men with type 2 diabetes

Skeletal muscle microvascular dysfunction and mitochondrial rarefaction feature in type 2 diabetes mellitus (T2DM) linked to low tissue glucose disposal rate (GDR). Exercise training and milk protein supplementation independently promote microvascular and metabolic plasticity in muscle associated with improved nutrient delivery, but combined effects are unknown. In a randomised-controlled trial, 24 men (55.6 y, SD 5.7) with T2DM ingested whey protein drinks (protein/carbohydrate/fat: 20/10/3 g; WHEY) or placebo (carbohydrate/fat: 30/3 g; CON) before/after 45 mixed-mode intense exercise sessions over 10 weeks, to study effects on insulin-stimulated (hyperinsulinemic clamp) skeletal-muscle microvascular blood flow (mBF) and perfusion (near-infrared spectroscopy), and histological, genetic, and biochemical markers (biopsy) of microvascular and mitochondrial plasticity. WHEY enhanced insulin-stimulated perfusion (WHEY-CON 5.6%; 90% CI -0.1, 11.3), while mBF was not altered (3.5%; -17.5, 24.5); perfusion, but not mBF, associated (regression) with increased GDR. Exercise training increased mitochondrial (range of means: 40%-90%) and lipid density (20%-30%), enzyme activity (20%-70%), capillary:fibre ratio (∼25%), and lowered systolic (∼4%) and diastolic (4%-5%) blood pressure, but without WHEY effects. WHEY dampened PGC1α -2.9% (90% compatibility interval: -5.7, -0.2) and NOS3 -6.4% (-1.4, -0.2) expression, but other messenger RNA (mRNA) were unclear. Skeletal muscle microvascular and mitochondrial exercise adaptations were not accentuated by whey protein ingestion in men with T2DM. ANZCTR Registration Number: ACTRN12614001197628. Novelty: Chronic whey ingestion in T2DM with exercise altered expression of several mitochondrial and angiogenic mRNA. Whey added no additional benefit to muscle microvascular or mitochondrial adaptations to exercise. Insulin-stimulated perfusion increased with whey but was without impact on glucose disposal.

MicroRNA Profiling in Adipose Before and After Weight Loss Highlights the Role of miR-223-3p and the NLRP3 Inflammasome

OBJECTIVE

Adipose tissue plays a key role in obesity-related metabolic dysfunction. MicroRNA (miRNA) are gene regulatory molecules involved in intercellular and inter-organ communication. It was hypothesized that miRNA levels in adipose tissue would change after gastric bypass surgery and that this would provide insights into their role in obesity-induced metabolic dysregulation.

METHODS

miRNA profiling (Affymetrix GeneChip miRNA 2.0 Array) of omental and subcutaneous adipose (n = 15 females) before and after gastric bypass surgery was performed.

RESULTS

One omental and thirteen subcutaneous adipose miRNAs were significantly differentially expressed after gastric bypass, including downregulation of miR-223-3p and its antisense relative miR-223-5p in both adipose tissues. mRNA levels of miR-223-3p targets NLRP3 and GLUT4 were decreased and increased, respectively, following gastric bypass in both adipose tissues. Significantly more NLRP3 protein was observed in omental adipose after gastric bypass (P = 0.02). Significant hypomethlyation of NLRP3 and hypermethylation of miR-223 were observed in both adipose tissues after gastric bypass. In subcutaneous adipose, significant correlations were observed between both miR-223-3p and miR-223-5p and glucose and between NLRP3 mRNA and protein levels and blood lipids.

CONCLUSIONS

This is the first report detailing genome-wide miRNA profiling of omental adipose before and after gastric bypass, and it further highlights the association of miR-223-3p and the NLRP3 inflammasome with obesity.

Thioperamide, the selective histamine H3 receptor antagonist, attenuates stimulant-induced locomotor activity in the mouse

The effects of the selective histamine H3 receptor agonist (R)-alpha-methylhistamine and antagonist thioperamide on stimulant-induced locomotor activity in the mouse were examined. Amphetamine (1 mg.kg-1 s.c.), apomorphine (2 mg.kg-1 s.c.) or cocaine (5 mg.kg-1 s.c.) increased locomotor activity. Neither thioperamide (10 mg.kg-1 i.p.) nor (R)-alpha-methylhistamine (20 mg.kg-1 i.p.) affected spontaneous locomotor activity in their own right. (R)-alpha-Methylhistamine (0.3, 3 or 20 mg.kg-1 i.p.) also had no effect on amphetamine (1 mg.kg-1 s.c.)-induced locomotor activity. In contrast, thioperamide (0.2-10 mg.kg-1 i.p. or 0.3-20 micrograms i.c.v.) inhibited, in a dose-dependent manner, the hyperactivity response induced by amphetamine (1 mg.kg-1 s.c.). (R)-alpha-Methylhistamine (20 mg.kg-1 i.p.) completely reversed the inhibitory response to thioperamide (2 mg.kg-1 i.p.). Thioperamide (2 or 10 mg.kg-1 i.p.) also inhibited apomorphine (2 mg.kg-1 s.c.)- and, to a lesser extent, cocaine (5 mg.kg-1 s.c.)-induced hyperactivity. We therefore conclude that antagonism of the central histamine H3 receptor inhibits, to a varying degree, the effects of locomotor stimulants.

Pharmacological activity of VUF 9153, an isothiourea histamine H3 receptor antagonist

The pharmacological activity of the histamine H3 receptor antagonist VUF 9153 (S-[3-(4(5)-imidazolyl)]propyl-N-(4-chlorobenzyl)isothiourea) has been investigated in vitro and in vivo. VUF 9153 displaced [3H]N alpha-methylhistamine binding to rat cortex/hippocampal membranes (pKi = 9.77 +/- 0.03) and antagonised the inhibitory responses to (R)-alpha-methylhistamine against electrical field stimulation in the isolated longitudinal smooth muscle preparation of guinea-pig ileum (pKB = 9.95 +/- 0.07). In these assays, VUF 9153 was 10-50-fold more potent than the prototype H3 receptor antagonist thioperamide. VUF 9153 showed no or very weak activity in in vitro functional assays for histamine H1 or H2 receptors. Systemic administration of VUF 9153 (s.c. or p.o.) dose-dependently inhibited the ex vivo binding of [3H]N alpha-methylhistamine to rat cortex/hippocampal membranes and dipsogenic responses induced by (R)-alpha-methylhistamine. Calculation of ED50 values, at the 1 h pretreatment time used, revealed that VUF 9153 administered s.c. or p.o., was approximately 2-fold weaker than thioperamide. These data indicate that, like thioperamide, VUF 9153 is a potent and selective antagonist for histamine H3 receptors in vitro, possesses the ability to penetrate the blood-brain barrier to access central H3 receptors and can inhibit H3 receptor-mediated functional responses in vivo.

Histamine H3 receptor-mediated modulation of water consumption in the rat

The effect of the selective H3 receptor agonist (R)-alpha-methylhistamine and antagonist thioperamide on water consumption in the rat were examined. (R)-alpha-Methylhistamine (0.1-20 mg.kg-1 i.p.) evoked a dose-dependent increase in water consumption the maximum effect being 310 +/- 23% (n = 67) above the vehicle control response. Thioperamide (0.2,2 and 10 mg.kg-1 i.p.) alone had no effect on water consumption. However, the stimulatory effect of (R)-alpha-methylhistamine on water consumption was antagonised by thioperamide in a dose-dependent manner, whereas the H1 receptor antagonist mepyramine and the H2 receptor antagonist loxtidine were without effect. It is therefore concluded that the H3 receptor may play a role in the regulation of water consumption in the rat.

Histamine H3 receptors modulate the release of [3H]-acetylcholine from slices of rat entorhinal cortex: evidence for the possible existence of H3 receptor subtypes

1. The effect of agents which interact with the histamine H3 receptor on potassium-stimulated tritium release from slices of rat entorhinal cortex preloaded with [3H]-choline is described. We have examined the effects of the selective H3 receptor agonist, (R)-alpha-methylhistamine (RAMH), and a number of H3 receptor antagonists, including the selective compound thioperamide, on the potassium-stimulated release of tritium. 2. In the presence of mepyramine and ranitidine, RAMH (0.01-10 microM) inhibited potassium-stimulated tritium release in a concentration-dependent manner, EC50 = 0.11 microM. The maximum inhibition was approximately 50%. 3. Thioperamide displaced the RAMH concentration-response curve to the right yielding a pKB value of 8.4. There was no change in the maximum response to RAMH. 4. Other H3 receptor antagonists, including impromidine and burimamide, also caused rightwards displacement of the linear portion of the RAMH concentration-response curve. However, phenylbutanoylhistamine and betahistine, which are reported to be relatively potent H3 receptor antagonists, showed very low affinity. 5. Thioperamide (0.001-1 microM) alone enhanced the potassium-stimulated release of tritium in a concentration-dependent manner. Maximum effects were observed at 0.1-1 microM thioperamide, enhancing release by approximately 20%. 6. Results are discussed in terms of the regulatory role of H3 receptors on acetylcholine release and the possible existence of H3 receptor subtypes.

Abscisic acid binding to subcellular fractions from leaves of Vicia faba

A centrifugation binding assay has been used to demonstrate the binding of [(3)H] (±) abscisic acid to membrane-rich fractions prepared from leaves of Vicia faba L. Kinetic analysis of this binding shows evidence of saturation of binding sites with increasing concentration of ligand. Scatchard analysis of these data yields a biphasic plot possibly indicating the presence of two types of binding sites. The dissocation constant for the high affinity site has been calculated to be 3.5×10(-8) mol 1(-1).