Sex- and tissue-dependent creatine uptake in response to different creatine monohydrate doses in male and female Sprague-Dawley rats.

Tyler C Dunham,Jensen E Murphy,Wendy E Ward,Val Andrew Fajardo,Rebecca E K Macpherson,Brian D Roy

doi:10.1139/apnm-2021-0301

Tyler C Dunham, Jensen E Murphy + Show 4 more

Open Access

https://doi.org/10.1139/apnm-2021-0301

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Abstract

Sprague-Dawley rats (n= 32) underwent 8-weeks of creatine monohydrate (CM) supplementation (0, 2.5, 5, and 10g/L). Total creatine (TCr) concentrations in female white fibre-dominant gastrocnemius (WGAS) and cardiac muscle (HRT) were significantly higher compared with males (p< 0.05). CM supplementation increased TCr concentrations in female WGAS (p< 0.05) and HRT (p< 0.01) and in male red fibre-dominant gastrocnemius muscle (RGAS) (p< 0.05). Future research should further investigate sex-differences in basal levels of TCr and the response to CM supplementation. Novelty: There is a sex- and tissue-dependant response to CM supplementation in rats.

Highlights

Creatine (Cr) is an organic compound which can be obtained through dietary consumption, endogenous synthesis, and supplementation in mammals
While the mechanisms underlying these differences have not been determined, it has been hypothesized that the sex hormones may play a role; estrogens and testosterone have been found to influence the expressions of AGAT, the rate-limiting enzyme responsible for Cr synthesis, as well as creatine kinase (CK) activity (Ellery et al 2016)
Total dietary intake of creatine monohydrate (CM) was higher in males as compared with females (p < 0.01); when CM intake was normalized to body mass, no differences were observed for sex (Table 1)

Summary

Introduction

Creatine (Cr) is an organic compound which can be obtained through dietary consumption, endogenous synthesis, and supplementation in mammals. Substrate utilization in skeletal muscle has been shown to be regulated by estrogens and progesterone, which may play an important role in Cr uptake and utilization (Ellery et al 2016). Despite these observations, investigations into sex-based differences in both resting Cr levels and the responses to dietary Cr supplementation have been limited.

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