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Melatonin administration increased plasminogen activator activity in ram spermatozoa
M P Tsantarliotou1, N A Kokolis, A Smokovitis
1Department of Physiology, School of Veterinary Medicine, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece. mtsant@vet.auth.gr
Theriogenology
|November 30, 2007
Summary
Melatonin supplementation in rams increased plasminogen activator activity (PAA) and inhibitors (PAI, PI) in spermatozoa, correlating with elevated testosterone levels. These changes may impact ram fertility.
Area of Science:
- Reproductive biology
- Endocrinology
- Biochemistry
Background:
- Melatonin is a hormone with seasonal effects on reproduction.
- Plasminogen activators and inhibitors (PAI, PI) are crucial for sperm function and fertilization.
- Testosterone levels fluctuate seasonally and influence reproductive parameters.
Purpose of the Study:
- To investigate melatonin's effect on plasminogen activator activity (PAA), plasminogen activator inhibition (PAI), and plasmin inhibition (PI) in ram spermatozoa and seminal plasma.
- To correlate these changes with blood testosterone levels.
- To assess potential impacts on ram fertility.
Main Methods:
- Subcutaneous melatonin implants (18 mg) were administered to sixteen Chios rams in autumn and spring.
- Semen samples were collected weekly for 17 weeks for spectrophotometrical assays.
- Blood samples were collected for testosterone assay (RIA) over 105 days post-implantation.
Main Results:
- Melatonin increased PAA and tissue-type PAI (t-PAI) in spermatozoa during autumn.
- In spring, melatonin further increased urokinase-type PAI (u-PAI) and PI in spermatozoa.
- No significant changes in PAA, PAI, or PI were observed in seminal plasma.
- Increased PAA, PAI, and PI in spermatozoa positively correlated with elevated testosterone (mean value, basal level, number of peaks), with greater increases in autumn.
Conclusions:
- Melatonin influences PAA, PAI, and PI in ram spermatozoa, potentially affecting fertilizing ability.
- The observed changes are linked to increased testosterone levels, particularly in autumn.
- These findings highlight melatonin's role in regulating sperm function and seasonal reproductive success in rams.
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