Stimulation of lactate production in human granulosa cells by metformin and potential involvement of adenosine 5' monophosphate-activated protein kinase.
BACKGROUND
Production of 3-carbon units (as lactate) by granulosa cells (GCs) is important in follicular and oocyte development and may be modulated by metformin.


OBJECTIVE
The aim of the study was to examine the action of metformin on GC lactate production and potential mediation via AMP-activated protein kinase (AMPK).


METHODS
GCs were prepared from follicular aspirates. After exposure to metformin and other potential modulators of AMPK in culture, aspects of cellular function were examined.


METHODS
The study was conducted in a private fertility clinic/university academic center.


METHODS
Women undergoing routine in vitro fertilization participated in the study.


METHODS
All agents were added in culture.


METHODS
Lactate output of GCs was measured. Cell extracts were prepared after culture, and phosphorylated forms of AMPK and acetyl CoA carboxylase (ACC) were assayed using Western analysis.


RESULTS
Metformin led to a rapid increase in lactate production by GCs [minimum effective dose, 250 microm; maximum dose studied, 1 mm (1.22-fold; P < 0.01)]. This dose range of metformin was similar to that required for stimulation of phospho-AMPK in GCs [minimum effective dose, 250 microm; maximum effect, 500 microm (2.01-fold; P < 0.001)]. Increasing phospho-ACC, as a representative downstream target regulated by AMPK, was apparent over a lower range (minimum effective dose, 31 microm; maximum effect, 250 microm; P < 0.001). A level of metformin (125 microm) insufficient for the stimulation of lactate output when used alone potentiated the effects of suboptimal doses of insulin on lactate production. Adiponectin (2.5 microg/ml) had a small but significant effect on lactate output.


CONCLUSIONS
Metformin activates AMPK in GCs, stimulating lactate production and increasing phospho-ACC. Metformin also enhances the action of suboptimal insulin concentrations to stimulate lactate production.
Richardson
Malcolm C
MC
Developmental Origins of Health and Disease Research Division, Institute of Developmental Sciences, University of Southampton, Southampton General Hospital, Tremona Road, Southampton SO16 6YD, United Kingdom. mcr2@soton.ac.uk
Ingamells
Susan
S
Simonis
Chantal D
CD
Cameron
Iain T
IT
Sreekumar
Rajiv
R
Vijendren
Ananth
A
Sellahewa
Luckni
L
Coakley
Stephanie
S
Byrne
Christopher D
CD
D055372:AMP-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology*; D052242:Adiponectin / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D006107:Granulosa Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D019344:Lactic Acid / Q000378:metabolism*; D008687:Metformin / Q000494:pharmacology*; D008954:Models, Biological; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects
D052242:Adiponectin; D007004:Hypoglycemic Agents; D007328:Insulin; D019344:Lactic Acid; D008687:Metformin; D055372:AMP-Activated Protein Kinases