Acute ingestion of a ketone monoester, whey protein, or their co-ingestion in the overnight postabsorptive state elicit a similar stimulation of myofibrillar protein synthesis rates in young males: a double-blind randomized trial

BACKGROUND

Ketone bodies may have anabolic effects in skeletal muscle via their capacity to stimulate protein synthesis. Whether orally ingested exogenous ketones can stimulate postprandial myofibrillar protein synthesis (MyoPS) rates with and without dietary protein co-ingestion is unknown.

OBJECTIVES

This study aimed to evaluate the effects of ketone monoester intake and elevated blood β-hydroxybutyrate (β-OHB) concentration, with and without dietary protein co-ingestion, on postprandial MyoPS rates and mechanistic target of rapamycin complex 1 (mTORC1) pathway signaling.

METHODS

In a randomized, double-blind, parallel group design, 36 recreationally active healthy young males (age: 24.2 ± 4.1 y; body fat: 20.9% ± 5.8%; body mass index: 23.4 ± 2 kg/m2) received a primed continuous infusion of L-[ring-2H5]-phenylalanine and ingested one of the following: 1) the ketone monoester (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (KET), 2) 10 g whey protein (PRO), or 3) the combination of both (KET+PRO). Blood and muscle biopsy samples were collected during basal and postprandial (300 min) conditions to assess β-OHB, glucose, insulin, and amino acid concentrations, MyoPS rates, and mTORC1 pathway signaling.

RESULTS

Capillary blood β-OHB concentration increased similarly during postprandial conditions in KET and KET+PRO, with both being greater than PRO from 30 to 180 min (treatment × time interaction: P < 0.001). Postprandial plasma leucine and essential amino acid (EAA) incremental area under the curve (iAUC) over 300 min was greater (treatment: both P < 0.001) in KET+PRO compared with PRO and KET. KET, PRO, and KET+PRO stimulated postprandial MyoPS rates (0-300 min) higher than basal conditions [absolute change: 0.020%/h; (95% CI: 0.013, 0.027%/h), 0.014%/h (95% CI: 0.009, 0.019%/h), 0.019%/h (95% CI: 0.014, 0.024%/h), respectively (time: P < 0.001)], with no difference between treatments (treatment: P = 0.383) or treatment × time interaction (interaction: P = 0.245). mTORC1 pathway signaling responses did not differ between treatments (all P > 0.05).

CONCLUSIONS

Acute oral intake of a ketone monoester, 10 g whey protein, or their co-ingestion in the overnight postabsorptive state elicit a similar stimulation of postprandial MyoPS rates in healthy young males. This trial was registered at clinicaltrials.gov as NCT04565444 (https://clinicaltrials.gov/study/NCT04565444).

An LC-MS/MS method for simultaneous analysis of up to six monoamines from brain tissues

Monoamines are a class of neuromodulators that are crucial for a variety of brain functions, including control of mood, movement, sleep and cognition. From mammals to insects, the nervous system is enriched in monoamines such as dopamine, serotonin and melatonin, analytes which range from being highly polar to non-polar. Here we developed a method using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) to quantify in a single run the amounts of six distinct monoamines in extracts from dissected Drosophila and mouse brain tissues. The measured monoamines were dopamine (DA), serotonin (also known as 5-hydroxytryptamine (5-HT)), octopamine (OA, an insect equivalent of norepinephrine), tyramine (TA), melatonin (MT) and N-acetylserotonin (NAS). The analytical range of these monoamines was between 0.25 and 5.0 ng/mL. This quantitative LC-MS/MS methodology has important use for simultaneous measurement of distinct neuroactive monoamines from precious biological specimens.

The acute effects of insect vs. beef-derived protein on postprandial plasma aminoacidemia, appetite hormones, appetite sensations, and energy intake in healthy young men

BACKGROUND/OBJECTIVES

The purpose of this study was to evaluate the acute effects of ingesting beef- and insect-derived protein on postprandial plasma amino acid and appetite hormone concentrations, appetite sensations, and ad libitum energy intake.

SUBJECTS/METHODS

In a randomized, double-blind, crossover study, 20 young men (23 (SD: 4) y) completed two trials during which arterialized blood samples and VAS questionnaires were collected at baseline, and over 300-min after ingestion of beverages with similar energy and macronutrient content containing 25 g beef- or insect-derived (cricket) protein. Blood samples were analyzed for plasma amino acid and appetite hormone concentrations, while VAS questionnaires were applied to assess appetite sensations. After each trial, an ad libitum meal was immediately provided to assess energy intake.

RESULTS

Adjusted mean postprandial incremental area under the curve (iAUC) was greater for cricket vs. beef-derived protein for plasma leucine, branched-chain amino acid, and essential amino acid concentrations (all P < 0.0001). Adjusted mean postprandial iAUC for hunger was lower following beef (-3030 (SE: 860)) vs. cricket-derived (-1197 (SE: 525)) protein (Difference: -1833 (95% CI: -3358, -308); P = 0.02), but was not different for other appetite sensations or appetite hormones (all P > 0.05). Adjusted mean ad libitum energy intake was 4072 (SE: 292) and 4408 (SE: 316) kJ following beef- and cricket-derived protein (Difference: -336 (95% CI: -992, 320); P = 0.30).

CONCLUSION

Acute ingestion of cricket and beef-derived protein leads to differences in postprandial plasma amino acid concentrations, but elicits similar effects on appetite hormones, appetite sensations, and ad libitum energy intake in young men.

Enhancing the uptake of dextromethorphan in the CNS of rats by concomitant administration of the P-gp inhibitor verapamil

Clinical trials evaluating high doses of dextromethorphan hydrobromide (DM) for the treatment of neurological disorders have resulted in numerous adverse events due to the presence of its active metabolite dextrorphan (DX). Since the uptake of drugs in the CNS can be modulated by P-glycoprotein (P-gp) inhibition at the blood-brain barrier (BBB), we propose to determine whether the P-gp inhibitor verapamil can enhance the uptake of DM in the CNS. Rats (n=42) received an oral dose of DM (20 mg/kg) alone or 15 min after an intravenous dose of verapamil (1 mg/kg). Rats were euthanized at different time points over 12 h, and concentrations of DM and DX (conjugated and unconjugated) were assessed in plasma, brain and spinal cord using a LC-ESI/MS/MS method. Pharmacokinetic parameters were calculated using noncompartmental methods. Verapamil treatments did not affect the biodisposition of DM in plasma. On the other hand, verapamil treatments increased the area under curve of DM in the brain (from 1221 to 2393 ng h/g) and spinal cord (from 1753 to 3221 ng h/g) by approximately 2-fold. The uptake of DX in brain and spinal cord were markedly lower than those of DM and increased by only 15% and 22% following verapamil treatments, respectively. These results suggest that the P-gp inhibitor verapamil can enhance the uptake of DM in the CNS without affecting that of DX. This change is most likely related to an inhibition of P-gp or other transporters located in the BBB since the biodisposition of DM in plasma remained unaffected by verapamil treatments.

Metabolism and disposition of resveratrol in rats: extent of absorption, glucuronidation, and enterohepatic recirculation evidenced by a linked-rat model

Pharmacokinetics of trans-resveratrol in its aglycone (RES(AGL)) and glucuronide (RES(GLU)) forms were studied following intravenous (15 mg/kg i.v.) and oral (50 mg/kg p.o.) administration of trans-resveratrol in a solution of beta-cyclodextrin to intact rats. In addition, the enterohepatic recirculation of RES(AGL) and RES(GLU) was assessed in a linked-rat model. Multiple plasma and urine samples were collected and concentrations of RES(AGL) and RES(GLU) were determined using an electrospray ionization-liquid chromatography/tandem mass spectrometry method. After i.v. administration, plasma concentrations of RES(AGL) declined with a rapid elimination half-life (T(1/2), 0.13 h), followed by sudden increases in plasma concentrations 4 to 8 h after drug administration. These plasma concentrations resulted in a significant prolongation of the terminal elimination half-life of RES(AGL) (T(1/2TER), 1.31 h). RES(AGL) and RES(GLU) also displayed sudden increases in plasma concentrations 4 to 8 h after oral administration, with T(1/2TER) of 1.48 and 1.58 h, respectively. RES(AGL) bioavailability was 38% and its exposure was approximately 46-fold lower than that of RES(GLU) (AUC(inf), 7.1 versus 324.7 micromol.h/l). Enterohepatic recirculation was confirmed in the linked-rat model since significant plasma concentrations of RES(AGL) and RES(GLU) were observed in bile-recipient rats at 4 to 8 h. The percentages of the exposures of RES(AGL) and RES(GLU) that were due to enterohepatic recirculation were 24.7 and 24.0%, respectively. The fraction of drug excreted in the urine over a period of 12 h was negligible. These results confirm that RES(AGL) is bioavailable and undergoes extensive first-pass glucuronidation, and that enterohepatic recirculation contributes significantly to the exposure of RES(AGL) and RES(GLU) in rats.