Intrafollicular and Systemic Dopamine, Noradrenaline and Adrenaline Concentrations in Cycling Mares.
Authors: Satué Katiuska, Fazio Esterina, Rubio Maria Dolores, Cravana Cristina, Medica Pietro
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Catecholamines in Equine Follicular Fluid Catecholamine neurotransmitters—dopamine, noradrenaline and adrenaline—regulate ovulation and oocyte maturation in various species, yet their role in equine reproductive physiology remained unclear until this 2020 investigation. Researchers analysed follicular fluid and blood samples from 60 ovaries collected during the breeding season, stratifying follicles by diameter (small: 20–30 mm; medium: 31–40 mm; large: ≥41 mm) and measuring intrafollicular and systemic catecholamine concentrations. Intrafollicular concentrations of all three catecholamines exceeded systemic levels significantly, with distinct size-dependent patterns: dopamine peaked in medium-sized follicles, noradrenaline in small follicles, and adrenaline in large follicles, whilst negative correlations existed between follicle diameter and noradrenaline/adrenaline levels. These findings suggest the follicle functions as a regulated catecholamine storage and release system, implicating local neurochemical signalling in normal ovarian function—evidence that could inform future research into fertility optimisation, stress responses affecting reproduction, and pharmacological interventions targeting follicular development in mares.
Read the full abstract on PubMed
Practical Takeaways
- •Understanding catecholamine regulation in follicular fluid may help explain variation in oocyte maturation and ovulation timing in mares, potentially improving breeding program management
- •The neuronal regulation of follicular development through catecholamines suggests stress and sympathetic nervous system activity could directly affect ovarian function and fertility in mares
- •Catecholamine profiles differ across follicle sizes, indicating distinct physiological roles at different stages of follicular maturation that could be relevant to timing of breeding interventions
Key Findings
- •Intrafollicular catecholamine concentrations (dopamine, noradrenaline, adrenaline) were significantly higher than systemic concentrations (p < 0.05)
- •Dopamine concentrations were highest in medium-sized follicles (31-40 mm), noradrenaline highest in small follicles (20-30 mm), and adrenaline highest in large follicles (≥41 mm)
- •Follicle diameter negatively correlated with noradrenaline and adrenaline concentrations (p < 0.05)
- •Follicular fluid serves as an intraovarian catecholamine storage compartment capable of regulated neurotransmitter release