OCEV: Oral Contraceptive vs Menstrual Cycle Ex Vivo Model
Study Details
Study Description
Brief Summary
Despite comprising half the population, females are often left out of muscle research due to the impact of changing hormones during the menstrual cycle and when using oral contraceptives. This makes it hard to perform costly and invasive studies involving tracers to study muscle protein metabolism. Consequently, we lack a clear understanding of how these hormonal changes affect muscle growth.
There is a need for less invasive methods to study how sex hormones and oral contraceptives influence muscle protein metabolism. Ex vivo models, where serum from participants is applied to mouse muscle cell cultures, mimic the conditions of human muscle cells and can provide initial insights.
| Condition or Disease | Intervention/Treatment | Phase |
|---|---|---|
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N/A |
Detailed Description
The aim of the study is to develop a non-invasive model using serum from both oral contraceptive users and non-users at various stages of their cycles, to understand if different cycle or pill stages affect how muscles process proteins.
Study Design
Arms and Interventions
| Arm | Intervention/Treatment |
|---|---|
| Experimental: Mid-Follicular Phase 7-11 days after onset of menses. |
Behavioral: Protein tracer drink
Subjects will be fed a mixed-macronutrient beverage at rest (0.75g/kg lean body mass of carbohydrates; 0.125g/kg lean body mass of protein). Amino acid composition of the protein will be modelled off the composition of egg. Leucine content will be enriched to 5% with [13 Carbon(13C)]-leucine.
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| Experimental: Mid-Luteal Phase 5-9 days after ovulation (as confirmed with ovulation test kits). |
Behavioral: Protein tracer drink
Subjects will be fed a mixed-macronutrient beverage at rest (0.75g/kg lean body mass of carbohydrates; 0.125g/kg lean body mass of protein). Amino acid composition of the protein will be modelled off the composition of egg. Leucine content will be enriched to 5% with [13 Carbon(13C)]-leucine.
|
| Experimental: Active pill phase 10-20 days after starting new pill cycle. |
Behavioral: Protein tracer drink
Subjects will be fed a mixed-macronutrient beverage at rest (0.75g/kg lean body mass of carbohydrates; 0.125g/kg lean body mass of protein). Amino acid composition of the protein will be modelled off the composition of egg. Leucine content will be enriched to 5% with [13 Carbon(13C)]-leucine.
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| Experimental: Withdrawal phase 48hrs after last pill (during placebo pill phase). |
Behavioral: Protein tracer drink
Subjects will be fed a mixed-macronutrient beverage at rest (0.75g/kg lean body mass of carbohydrates; 0.125g/kg lean body mass of protein). Amino acid composition of the protein will be modelled off the composition of egg. Leucine content will be enriched to 5% with [13 Carbon(13C)]-leucine.
|
Outcome Measures
Primary Outcome Measures
- Protein Synthesis (Murine Cell-Based Experiments, ex-vivo experiments) [60 minutes]
Investigators will use human serum obtained from fasted and fed timepoints (-15, 20, 40 and 60 minutes following beverage consumption) to condition cell culture media (20% volume). To determine the effects of using fasted and/or fed 'human-conditioned' culture media on cell protein synthesis, puromycin incorporation (measure of protein synthesis) will be measured via western blot and expressed relative to a no-serum control. A two-way repeated measures ANOVA will be used to analyze outcomes with cycle stage and group (OC vs non-OC) used as factors
Secondary Outcome Measures
- Whole-body protein synthesis [6 hours]
Investigators will measure the enrichment of [13 Carbon CO2 (13CO2)] in the breath by isotope ratio mass spectrometry (IRMS) in atom percent excess (APE). The measurement of carbon dioxide production (VCO2) and stable isotope tracer enrichment in the breath allows for the assessment of the rate at which amino acids are used for energy (i.e., oxidized), rather than for protein synthesis (i.e., retained in the body) by calculating the fraction of expired CO2 that contains 13C. Leucine retention (umol/kg) will then be calculated from the difference between the known amount of leucine provided (ingested) and leucine oxidation (as determined from 13CO2 breath enrichment).
- Urinary Measures (Muscle Protein Breakdown) [6 hours]
Investigators will measure urinary 3-methylhistidine (3MH) as an indirect marker of muscle protein breakdown over the course of the trial (6 hours) through pooled urine collection vs baseline urine.
Eligibility Criteria
Criteria
Inclusion Criteria:
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BMI between 18.5-29.9 kg/m2 (I.e., non-obese).
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For OC users: on monophasic OCs for > 3 months prior to study enrollment
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For non-OC users: regular menstrual cycles length (25-35 days) for at least 3 months prior to study and at least 6 months off of OCs.
Exclusion Criteria:
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Chronic disease diagnosis (cardiovascular, thyroid, diabetes)
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Current or recent remission of cancer
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Regular use of NSAID (except low-dose aspirin), anticoagulants
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Use of prescription drugs that would impact metabolism, e.g. Statins, Lithium, Attention-Deficit/Hyperactivity Disorder (ADHD) medication.
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Insertion of intrauterine device (IUD) - exception: copper
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Use of ergogenic aids such as creatine
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Regular Tabacco use
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Use of illicit drugs (growth hormones, testosterone)
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For non-OC users: Use of oral contraceptives for > 6 months prior to study enrollment
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to ensure return to regular menstrual cycle.
Contacts and Locations
Locations
| Site | City | State | Country | Postal Code | |
|---|---|---|---|---|---|
| 1 | Goldring Centre for High Performance Sport at the University of Toronto | Toronto | Ontario | Canada | M5S2C9 |
Sponsors and Collaborators
- University of Toronto
Investigators
- Study Director: Ines Kortebi, PhD Student, University of Toronto
- Study Director: Cassidy Tinline-Goodfellow, PhD (C), University of Toronto
- Study Director: Jonathan Aguilera, PhD Student, University of Toronto
Study Documents (Full-Text)
None provided.More Information
Publications
None provided.- OCEV