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. 2023 Apr-Jun;24(2):69–84. doi: 10.18502/jri.v24i2.12491

Table 5.

Summary of the selected human studies on cryoprotective effect of L-carnitine on freeze–thaw induced sperm damages

Authors Species and number Treatment Dosage Freezing and thawing media and procedures Results
Parmornsupornvichit et al. (2013) 24 healthy cats of various breeds, aged between 1–7 years L-carnitine (LC) Groups: i) 0 mM LC (control), ii) 12.5 mM LC, and iii) 25 mM LC

  • - Freezing: fast freezing.

  • - Freezing medium: Tris based glucose extender containing Tris, citric acid, glucose, benzylpenicillin sodium, streptomycin sulfate, LC, and glycerol.

  • - Thawing: immersing the straw in warm water (37°C) for 15 s.

  • - Thawing medium: Tris-based glucose extender without egg yolk, LC, or glycerol

  • - Significantly higher motility was observed in 25 mM LC group when compared with 0 mM LC (control) group 0 hr and 2 hr after thawing.

  • - Significantly higher sperm motility 2 hr after thawing of 12.5 mM and 25 mM LC in comparison to 0 mM LC.

  • - Plasma membrane integrity, DNA integrity, and acrosome integrity were not significantly different in all treatment groups and all examination times
Sarıözkan et al. (2014) 10 sexually mature male New Zealand white rabbits

  • - L-carnitine (LC)

  • - Glutamine

  • - LC doses: 0.5, 1, and 2 mM.

  • - Groups: 4 equal aliquots containing 0 (control), 0.5, 1, and 2 mM of LC

 Freezing: cooling semen samples from 37 to 5°C, in a cold cabinet, maintaining at 5°C, and then examining after 0, 6, 12, and 24 hr of liquid storage

  • -3 different doses of LC provided significant increases in the percentage of motile sperm at 12 hr and 24 hr and significant protection of the sperm plasma membrane was observed at 12 and 24 hr of cool-storage, in comparison to the control samples.

  • - Only the 2 mM dose of LC significantly decreased the rate of acrosome damage in comparison to the control samples
Fattah et al. (2016) 12 adult male roosters L-carnitine (LC) Groups: Beltsville without LC (control), Beltsville with 0.5 mM (L0.5), 1 mM (L1), 2 mM (L2), 4 mM (L4), and 8 mM (L8) LC

  • - Freezing: equilibration at 5°C for 3 hr, freezing the straws in liquid nitrogen vapor, 4 cm above the liquid nitrogen, for 7 min and then, plunging them into liquid nitrogen.

  • - Freezing medium: Beltsville.

  • - Thawing: The frozen straws were thawed at 37°C for 30 s in a water bath

  • - 2 different doses of LC provided higher total motility, progressive motility, membrane functionality, viability, and significantly lowered lipid peroxidation compared to control group.

  • - Lower motility, progressive motility, and viability were observed in frozen-thawed sperm in extender containing 8 mM LC compared to control group.

  • - Morphology and mitochondrial activity were not affected by 2 doses of LC