Spermatozoa require a continuous supply of ATP to maintain motility as they travel through the male and female reproductive tracts. They produce ATP through both anaerobic glycolysis and aerobic respiration. Glycolytic enzymes are located in the fibrous sheath of the principal piece, while the machinery for oxidative phosphorylation is located in the mid-piece. Both pathways are important for energy production, though glycolysis may play a larger role in supporting the high ATP demands along the length of the flagellum. The rates of sperm metabolism can be influenced by various environmental factors.

1. Metabolism of SpermatozoaMetabolism of Spermatozoa
Rahul Katiyar
PhD Scholar
Roll No.- P-1856

2. WHY METABOLISM NEEDED?WHY METABOLISM NEEDED?
 Spermatozoa  dynamic structure
 The sperm require a continuous supply of ATP to
maintain motility in the male and female
reproductive tract
 During epididymal maturation and later in the
female reproductive tract when they undergo
capacitation and hyperactivation

3. PATHWAYS OF ENERGY PRODUCTION INPATHWAYS OF ENERGY PRODUCTION IN
SPERMATOZOASPERMATOZOA
 Metabolism: Anaerobic &
Aerobic Respiration
 ATP production by oxidative phosphorylation &
glycolysis

4. ATP PRODUCTION SITES IN SPERMATOZOAATP PRODUCTION SITES IN SPERMATOZOA
 Machinery for oxidative phosphorylation Mid-
Piece
 Glycolytic enzymes tethered to the fibrous
sheath of the principal piece
(Storey and Kayne 1975; Krisfalusi et al. 2006,
Plessis et al., 2015)

5. SITE OF ATP PRODUCTION VIASITE OF ATP PRODUCTION VIA
OXIDATIVE PHOSPHORYLATIONOXIDATIVE PHOSPHORYLATION
 Mitochondria referred as power house of cell.
 Occupies substantial portion of total cellular volume
( 15-22%).
 Mature spermatozoa contains approx. 72-80
mitochondria.
 CRISTAE are principle sites of OXPHOS and ATP
generation

6.  Sperm mitochondria possess Cytochrome c
( Nariswa et al., 2002) , Hexokinase subunit VIb of
cytochrome C Oxidase( Huttemann et al., 2003)
and lactate dehydrogenase (Blanco et al., 1963).

7. SITE OF ATP PRODUCTION VIASITE OF ATP PRODUCTION VIA
GLYCOLYSISGLYCOLYSIS
 Head and principle piece are devoid of respiratory
enzymes.
 Several glycolytic enzymes have been found in
fibrous sheath of spermatozoa which include-
 Hexokinase
 Phosphoglucokinase isomerase
 Phosphofructokinase
 Glyceraldehyde-3- phosphate dehydrogenase
( Kim et al., 2007)

8. Energy substratesEnergy substrates
• Glycolytic substrates: Glucose, mannose, fructose, and
sorbitol
• Non-glycolysable substrates: pyruvate, lactate, and
hydroxybutyrate
• Glucose, mannose, fructose, and sorbitol  high
percentage of motile sperm and support the increase in
phosphorylation
• Fructose and sorbitol  does not support
hyperactivation
(Goodson et al., 2012 )
• Bull sperms prefer glucose over fructose

9. • Non-glycolysable substrates maintain motility
with only low levels of tyrosine phosphorylation and
hyperactivation
• Pyruvate, lactate  able to sustain high ATP levels
• Citrate  not able
• Citrate is not permeable to mitochondria
• Needs to be converted to malate with the use of
ATP to be able to enter the citric acid cycle

10. GlycolysisGlycolysis
 Provides less efficient, but very high - throughout production
of ATP locally down the length of the principal piece
 Net yield of 2 molecules of ATP per molecule of glucose
oxidized
 Glycolysable substrates must be able to pass through the
plasma membrane of the flagellum
 In the flagella of murine sperm GLUT3 is the primary
facilitative glucose transporter (Simpson et al. 2008)
 In bovine sperm  uptake of is mediated by GLUT5
(Angulo et al. 1998)

12.  Most of the steps in this process are catalyzed by
sperm-specific isoforms of the respective proteins
 Pyruvate is used to regenerate NAD+
from NADH 
converted into lactate by LDH
 The NAD regeneration is essential for continuing
glycolysis

13. TCA Cycle

14. Oxidative Phosphorylation

15. Glycolysis or OxidativeGlycolysis or Oxidative
Phosphorylation???Phosphorylation???
 Controversy over the relative importance of
glycolysis and oxidative phosphorylation
 It is suggested that sperm glycolysis is the main
pathway to support motility.
(Miki et al. 2004)

17. Evidence for functional importance of
glycolysis –
 Glucose, but not lactate or pyruvate, is required for
the protein tyrosine phosphorylation -- events
observed during the process of sperm capacitation
(Travis et al. 2001)
 Inhibiting electron transfer or uncoupling oxidative
respiration  did not impact the sperm’s ability to
regulate patterns of motility
(Travis et al. 2001)

18.  Inhibition of mitochondrial function was found not to
impair motility and to have little effect on intracellular
ATP levels (Mukai and Okuno
2004)
 Addition of DOG (2-deoxyglucose)  inhibited motility
and led to depletion of ATP
(Mukai and Okuno 2004)
 Gene knock out of the germ cell specific isoform of
GAPDH  defects in sperm motility and fertility
( Miki et al., 2004)

19.  Large amounts of ATP are required along the full
length of the motile flagellum
 ATP produced by the mid piece mitochondria 
unable to diffuse sufficiently along the length of the FS
to supply the entire flagellum to support the axonemal
dynein ATPase

20.  Humans appear to be one mammalian species whose
sperm do rely substantially, if not entirely, on
glycolysis for motility
(Ford and Rees, 1990; Williams and Ford, 2001)

21. Measurement of metabolismMeasurement of metabolism
Rate of anaerobic glycolysis:
• ZN
2LA  Expressed as number of units of lactic acid
produced by a standard number of sperm cells (100
× 106
sperm) in a given time (1 hour)
• For good quality spermatozoa-- 200µg
• Fructolytic index  the mg of fructose used by 1
billion spermatozoa in 1 hr at 37° C under anaerobic
conditions.
• Normal value  1.5 – 2 mg/billion cells

22. Measurement of aerobic respiration
• By Metylene blue reduction test or resazurine
reduction test
• Direct determination of O2 consumption in
microrespirometers (Warburg respirometer)
• ZO2 = µl of O2 consumed by 100X106
cells in 1 hr at
37o
C.
• Normal value- 21

23. Factors influencing metabolic ratesFactors influencing metabolic rates
of bull spermatozoaof bull spermatozoa
 Temperature
 Cell concentration
 Inorganic P
 pH
 Cations
 Anions
 Osmotic pressure
 Hormones
 Anti-bacterial agents

24. ConclusionConclusion
 Glycolysis provides less efficient, but very high-
throughout production of ATP locally down the length
of the principal piece
 Mitochondrial respiration and glycolysis can
compensate for each other but they do not have
obligatory roles in maintaining sperm ATP production
and sperm motility

25. Thank You