PSXIII-10 Effects of short-term dexamethasone administration on glucose and insulin dynamics and muscle protein signaling in horses after the consumption of a high protein meal.

Loos, C.M.M.; Dorsch, Simone; Gerritsen, Arnout F.; Barnes, Tyler; Urschel, Kristine L.

doi:10.1093/jas/sky404.548

Cited by 2 publications

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“…There were no differences in the degree of phosphorylation of mTOR and rpS6 between the ID and non-ID groups for either protein source, indicating that AA uptake by the muscle and subsequent mTOR pathway activation in response to a protein meal was not impaired in ID horses. These data are in accordance with previous work in horses using a glucocorticoid-induced model of IR where mTOR pathway activation in response to a protein meal was not different from healthy control horses despite clear evidence of IR ( 55 ). This study extends these findings in horses with naturally occurring ID.…”

Section: Discussionsupporting

confidence: 92%

“…Regardless of treatment, ID horses had overall higher levels of phosphorylated rpS6. A similar response was observed post feeding a protein meal in glucocorticoid-induced IR horses ( 55 ). Considering ID horses tended to have slightly higher peak plasma leucine concentrations, this may have provided stronger stimulation of S6K1 and subsequently rpS6 as it has been shown that leucine can also directly increase S6K phosphorylation downstream of mTOR ( 44 ).…”

Section: Discussionsupporting

confidence: 75%

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Differential effect of two dietary protein sources on time course response of muscle anabolic signaling pathways in normal and insulin dysregulated horses

et al. 2022

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The objective of the study was to characterize the temporal changes of phosphorylation patterns of mTOR signaling proteins in response to two dietary protein sources in insulin dysregulated (ID, n = 8) and non-ID (n = 8) horses. Horses were individually housed and fed timothy grass hay and 2 daily concentrate meals so that protein was the first limiting nutrient and the total diet provided 120% of daily DE requirements for maintenance. On sample days, horses randomly received 0.25 g CP/kg BW of a pelleted alfalfa (AP) or commercial protein supplement (PS). Blood samples were collected before and 30, 60, 90, 120, 150, 180, 210, 240, 300, 360, 420, and 480 min post feeding and analyzed for plasma glucose, insulin and amino acid (AA) concentrations. Gluteus Medius muscle samples were obtained before and 90, 180, and 300 min after feeding and analyzed for relative abundance of phosphorylated mTOR pathway components using western immunoblot analysis. There was no effect of protein source on postprandial glucose and insulin responses (P ≥ 0.14) but consumption of PS elicited a 2 times larger AUC for essential AA (EAA), greater peak concentrations of EAA and a shorter time to reach peak EAA concentrations compared to AP. Abundance of phosphorylated mTOR (P = 0.08) and rpS6 (P = 0.10) tended to be ~1.5-fold greater after consumption of PS at 90 min compared to AP. Dephosphorylation patterns differed between protein sources and was slower for AP compared to PS. ID horses had a 2 times greater (P = 0.009) AUC and 3 times higher postprandial peak concentrations (P < 0.0001) for insulin compared to non-ID horses after consumption of both treatment pellets, but EAA responses were similar between groups (P = 0.53). Insulin status did not affect rpS6 or mTOR phosphorylation after consumption of either protein source (P ≥ 0.35), but phosphorylated rpS6 abundance was twice as high in ID compared to non-ID horses (P = 0.007). These results suggest that the consumption of higher quality protein sources may result in greater postprandial activation of the mTOR pathway compared to equal amounts of a forage-based protein source. Moreover, ID does not impair postprandial activation of mTOR and rpS6 proteins in horses following a protein-rich meal.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 75%

Differential effect of two dietary protein sources on time course response of muscle anabolic signaling pathways in normal and insulin dysregulated horses

et al. 2022

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Complete abdominal wall rupture in a late‐term pregnant mare with pre‐existing prepubic tendon rupture

Timmins,

Ruby,

Wong

et al. 2024

Equine Veterinary Education

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SummaryA 15‐year‐old multiparous Quarter Horse mare with a pre‐existing (>1 year) prepubic tendon rupture was presented pregnant (approximately 310 days gestation) with mild signs of generalised discomfort and an advanced degree of cervical relaxation. The foal was declared to be the priority in an emergency situation; therefore, intravenous dexamethasone (0.1 mg/kg bwt i.v. q24h) was administered in an attempt to mature the fetus in case urgent induction of parturition was required. Within 36 h of admission, the mare developed a complete rupture of the caudoventral body wall and skin, from the anus to the cranial aspect of the mammary gland. Because eventration had occurred, the mare underwent immediate euthanasia and terminal caesarean section via a modified approach. The colt foal was euthanised on humane grounds, due to an inability to breathe without a ventilator, following 72 h of intensive care. Rebreeding mares with prepubic tendon rupture is not recommended, this case report presents important evidence that rebreeding mares with this condition can have fatal consequences.

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PSXIII-10 Effects of short-term dexamethasone administration on glucose and insulin dynamics and muscle protein signaling in horses after the consumption of a high protein meal.

Cited by 2 publications

References 0 publications

Differential effect of two dietary protein sources on time course response of muscle anabolic signaling pathways in normal and insulin dysregulated horses

Differential effect of two dietary protein sources on time course response of muscle anabolic signaling pathways in normal and insulin dysregulated horses

Complete abdominal wall rupture in a late‐term pregnant mare with pre‐existing prepubic tendon rupture

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