Effect of PUFA on Male & Female Reproduction Urmia University,Iran Jul. 2014

1. Effect of PUFA on Male & Female Reproduction
Supervisor: Dr. Alijoo
Presenter: M. Behroozlak
Jul. 2014

2. Introduction
• Fats and oils include both saturated fatty acids (SFA) and
mono- and polyunsaturated fatty acids (MUFA and
PUFA, Tables 1 for summary abbreviations used).
• PUFAs have more than one double bond present within
the molecule and are further classified into three groups
on the basis of their chemical structure:
 omega-3 (n-3), omega-6 (n-6) and omega-9 (n-9), where
the first double bond is located 3, 6, or 9 carbons from
the methyl end of the molecule.
2

3. Nutritionally important n-6, n-3 PUFA
3

4. Introduction
• Animals cannot synthesize n-6 or n-3 fatty acids de novo
as they lack the appropriate fatty acid desaturase
enzymes.
• The n-6 PUFA linoleic acid (LA) and the n-3 PUFA a-
linolenic acid (ALA) therefore need to be provided in
the diet as they are absolutely necessary for numerous
processes, including growth, reproduction, vision, and
brain development
4

5. n-6, n-3 PUFA metabolic pathway
• The main dietary n-6 PUFA is LA, which is abundant in
vegetable oils such as corn, safflower, sunflower and
rapeseed oils. Most n-3 PUFAs are derived from ALA,
found mainly in the chloroplasts of green vegetables and
grass.
• These two essential fatty acids can be converted in the
liver to longer chain PUFAs by desaturation and
elongation enzyme systems common to both pathways
5

6. 6
Liver

7. Mechanisms by which PUFAs can affect
Reproduction
 PUFAs and Prostaglandins:
• Twenty carbon PUFAs are the direct precursors of a larg
group of physiologically active compounds called
eicosanoid which include prostaglandins (PGs),
thromboxanes, leukotrienes and lipoxins.
• The 1- and 2-series PGs are derived from the n-6 PUFAs
DGLA and AA respectively, whereas the 3-series PGs
are derived from EPA.
• The synthesis of PGs in tissues throughout the body is a
very tightly regulated process.
7

8. 8

9. Functions of PGs related to reproduction
• Prostaglandins are key hormones both in terms of
cervical ripening and myometrial contractility, which are
essential for mammalian parturition. Therefore, the
connection can be made between changes in dietary
intake of PUFAs and the ensuing changes in gestational
length.
• Changes in PUFA intake through altering the pattern of
prostaglandin production may influence either the timing
or efficiency of the onset of labour.
9

10. Functions of PGs related to reproduction
• In general, animals or humans fed diets high in n-3 PUFAs
exhibited an increase in gestational length.
• This has been attributed to the changed pattern of PG
synthesis, which gives rise to an increase in the generation
of 3-series prostaglandins.
• Since 3-series prostaglandins are less potent than the 2-
series prostaglandins (e.g. in terms of inducing contraction)
normally associated with parturition, the suggestion is that
the biological activity of these 3-series prostaglandins is
insufficient to induce the vigorous myometrial contractions
associated with normal labour. 10

11. Functions of PGs related to reproduction
• Evidence exists to support the idea that normal onset of
labour is associated with an increase in n-6 PUFA derived
dienoic prostaglandins:
 (1) plasma levels of linoleic and arachidonic acid (both n-
6) are higher than those of linolenic acid, EPA and DHA
(all n-3) in women in labour.
 (2) levels of arachidonic acid increased throughout
pregnancy, with highest levels being observed during
labour, followed by a rapid decline postpartum;
 (3) levels of linoleic acid (the precursor of arachidonic
acid) increased in uterine arteries during pregnancy. 11

12. Synthesis of prostaglandins (PG)
12
Diet
PUFA
(PTGS1,2)

13. PUFAs and Steroidogenesis
• AA and its metabolites have long been implicated in
steroidogenesis through direct effects on the
steroidogenic machinery (e.g., steroid acute regulator
[STAR] protein, cytochrome P450, family 11, sub
family A, polypeptide 1 enzyme [CYP11A1]), or
indirect effects via PGs.
13
STAR plays a critical role in regulating steroid
synthesis

14. PUFAs and Steroidogenesis
• In Leydig cells, inhibition of endogenous release of AA
inhibited dibutyryl cAMP-induced steroid synthesis as
well as STAR promoter activity, Star mRNA and STAR
protein, whereas addition of exogenous AA reversed all
these effects.
14
AA can stimulate the production of testosterone via
effects on STAR.

15. PUFAs and Steroidogenesis
• In contrast, the age-dependent inhibition of testosterone
production involves the suppression of STAR as a
consequence of oxidative stress. The cause of the latter is
not known for certain, but is correlated with excessive
AA flux through the PTGS2 pathway.
• PUFAs can also regulate adrenal steroidogenesis. Basal
corticosterone synthesis was stimulated by LA.
15

16. PUFAs and Preterm Labor
• Preterm birth occurs in about 10% of all human
pregnancies and is associated with 70% of neonatal
deaths.
• Both fetal and maternal tissues, including amnion,
chorion, and decidual endometrium, synthesize PGs in.
The levels of PGs along with their synthetic enzymes
(mainly PTGS2) increase either before or at the time of
labor.
16

17. PUFAs and Preterm Labor
• PUFAs may thus be able to influence the timing of
parturition through alterations to PG or adrenal steroid
synthesis. A diet high in n-6 PUFAs is generally thought
to be associated with an increased risk of preterm delivery.
• In women, low n-3 PUFA consumption during pregnancy
is also associated with a higher risk of preterm labor and
low birth weight. Conversely, a diet high in n-3 PUFA is
associated with an increase in gestational length and birth
weight in rats and human populations with high fish
consumption.
17

18. PUFAs and Preterm Labor
• Women with a previous preterm delivery had a
significantly lower recurrence following EPA and
DHA supplementation in comparison with a placebo
group, reducing the risk from 33% to 21%.
• A further trial that provided women with DHA-
enriched eggs found fewer low-birth-weight and
preterm babies and a larger placental size.
18

19. PUFAs and Male Fertility
• Long chain PUFAs have been detected in the spermatozoa
of man and a variety of livestock species including both
mammals (ram, bull, boar) and birds (chickens, ducks,
turkeys).
• In birds, the most abundant were the n-6 PUFAs AA (5%–
9%) and docosatetranoic acid (22:4 n-6,15%–21%). These
were synthesized from LA, which was the most abundant
PUFA in the diet (15%), but was present at a lower
concentration in spermatozoa (2%–3%).
• Altering the PUFA sources in the diet resulted in
concomitant changes in the n-6 and n-3 composition of
sperm (e.g., boar, cockerel) 19

20. PUFAs and Male Fertility
• Spermatozoa require a high PUFA content to provide the
plasma membrane with the fluidity essential at
fertilization.
• However, this makes spermatozoa particularly vulnerable
to attack by reactive oxygen species (ROS), initiating a
lipid peroxidation cascade that can seriously compromise
the functional integrity of these cells, and lifestyle factors
promoting oxidative stress have clear associations with
reduced fertility.
20

21. PUFAs and Male Fertility
• The fluids bathing the spermatozoa during their passage
through the male reproductive tract are endowed with
highly specialized secreted forms of antioxidant enzymes.
• The latter include members of the glutathione peroxidase
and periredoxin families as well as superoxide dismutase
and a host of small molecular mass free radical
scavengers, including carnitine, tyrosine, uric acid, and
vitamin C.
21
Seminal plasma is recognized as one of the most
powerful antioxidant fluids known to man.

22. PUFAs and Male Fertility
• Experiments on chickens have shown that feeding more
PUFAs in the diet reduced the antioxidant status and
quality of the semen (sperm concentration, semen
volume).
• The importance of lipid peroxidation in this context was
suggested by the ability of vitamin E, a chain breaking
antioxidant, to reverse the negative impact of PUFA
supplementation.
22

23. PUFAs and Male Fertility
• A causative relationship between the retention of high
levels of unsaturated fatty acid and ROS generation was
indicated by a recent study indicating that exposure of
human spermatozoa to the PUFAs LA, AA, and DHA
triggered free radical generation, lipid peroxidation, and
DNA damage in human spermatozoa.
23

24. A proposed mechanism by which
unsaturated fatty acids might generate oxidative
stress in human spermatozoa.
24

25. Fats and egg yolk
• Fats present in the egg yolk are the main source of energy
for the developing chick embryo. It was shown that
alteration in the fatty acid profile of yolk fat decreased
chick embryonic survival.
• Effects of fats on decrease hatchability:
 Dietary cyclopropene fatty acids (i.e. sterculic and
malvalic acids) are examples of the fatty acids that
significantly decrease the hatchability of eggs supposedly
by increasing the ratio of stearic (C18:0) to oleic acid
(C18:1, n−9) in the egg yolk.
25

26. Effects of fats on decrease hatchability
 Similar to cyclopropene fatty acids, adverse effects on
hatchability of fertile eggs were observed when
conjugated linoleic acid (CLA) was fed in a low-fat diet.
 Dietary CLA caused a decrease in the levels of
C16:1(n−7) and C18:1(n−9) and an increase in the levels
of C16:0 and C18:0 in the egg yolk, probably by down
regulating stearoyl-CoA denaturize, an enzyme
catalyzing the conversion of C16:0 and C18:0 into
C16:1(n−7) and C18:1(n−9), respectively.
26

27. C18:1(n−9)
• C18:1(n−9) in the egg yolk was shown to play an
important role in the esterification of cholesterol and the
subsequent uptake of yolk lipid by the chick embryo. If
the ratio of C18:0 to C18:1(n−9) in the egg yolk
exceeded 0.3, embryo mortality occurred.
27
C18:1(n−9) plays an important role in chick embryo
development and survival.

28. Effects of various dietary fats on
hatchability in fertile eggs
28

29. 29

30. • Adding O appeared to reduce the residual yolk possibly
by increased transport of yolk components from yolk
sac into the chick liver compared to those from the
groups of CLA.
• These data showed that transport of yolk components
from yolk sac into chick was reduced in the CLA + LA
and CLA group compared to those from the CLA +O or
LA group.
30

31. Effect of UFA on hatch
• If the maternal diet contained additional oils high in
unsaturated fatty acids, even though the percentage of
C18:1(n−9) in the egg yolk dropped to 24%, percent
hatch of eggs was not influenced compared to the control
(Aydin, 2006).
• In the present study, this suggests that lowering
C18:1(n−9) of egg yolk by maternal dietary CLA may
not be the cause of the embryo mortality in fertile eggs.
31
The total UFA may be a more important predictor
of hatchability.

32. Effect of n-3/n-6 fatty acid ratio on
Reproduction in male
• Sperm cells contain very high proportions of
polyunsaturated fatty acids (PUFA), and normal
spermatozoa possess a higher percentage of the most
representative PUFA (C22:6 n-3) than those detected in
blood serum phospholipids and in other cell membranes.
• The lipid composition, the degree of PUFA unsaturation,
and the proportion of sperm PUFA have been shown to
affect sperm quantity.
• The n-6 PUFA and the n-3 PUFA need to be provided in
the diet.
32

33. Effect of n-3/n-6 fatty acid ratio on
Reproduction
• Researchers have shown the beneficial role of an
appropriate dietary n-3/n-6 ratio for embryo development
and health.
• It is thought that both man and livestock species evolved on
a diet with an n-6 to n-3 PUFA ratio of 1-2:1 but modern
dietary trends have increased this ratio. It now ranges from
10:1 to 25:1 in westernized human populations.
33
Therefore, in both human and animal diets there
are grounds for maintaining the proper ratio of n-6 and
n-3 PUFAs dietary intakes to promote reproduction.

34. Effects of different ratio of N-3/N-6 on semen
characteristics
• The male rats were fed diets containing 7% oil from soybean and
flaxseed for 60 days. The basic formulation of the experimental
diets contained supplemental ratios of soybean oil (SO): flaxseed
oil (FO), namely 100:0, 75:25, 50:50, 25:75, and 0:100. The ratios
of dietary n-3/n-6 PUFAs were 0.13, 0.40, 0.85, 1.52, and 2.85.
34

35. Effects of different ratios of N-3/N-6 PUFAs on
testis histological changes
• Compared with the control group, better spermatogonial
development and more uniform distribution of chromatin
around the nuclear membrane was observed in the group
with a n-3/n-6 PUFA ratio of 1.52 (diet 4).
35

36. Effects of different ratios of N-3/N-6 PUFAs
on the serum hormone levels
36

37. Lipid content of sperm and dietary fat
• Research has shown that diets containing distinct lipid
sources differentially modified the lipid contents of the
sperm head and body membranes, resulting in significant
improvement in semen quality.
• Al-Daraji et al. found the proportion of n-3 fatty acids in
spermatozoa from Japanese male quail fed fish oil
compared with corn oil was higher (9.6% vs. 4.3%) and
that of n-6 fatty acids was lower (22.4% vs. 33.3%).
• The sperm of flaxseed-fed rabbits had an n-3/n-6 ratio two
times higher compared with the control because of the
increasing dietary n-3/n-6 ratio. 37

38. Results about n-3/n-6 ratio
• Results of this study clearly indicate that the ratios of
n-3/n-6 PUFAs in the diet have a great influence on
sperm quality traits and reproductive performance, and
that a n-3/n-6 PUFAs ratio of 1.52 improved the
reproductive capacity of male rats.
38
A balanced n-3/n-6 PUFA ratio will be beneficial
to male reproduction. Therefore there is a necessity
to determine an appropriate n-3/n-6 PUFA ratio in
man and different male animals in the future.

39. Effect of Dietary Fat on the Fatty Acid
Composition and Fertilizing Ability of Fowl Semen
• The reproductive efficiency of male fowl, especially the
heavy breeds, needs to be improved. In mammals, the
lipid composition of sperm membranes plays a major
role in the physicochemical modifications leading to
fertilization.
• In birds, the lipid composition of spermatozoa may have
an influence on fertility.
39

40. PUFA & Phospholipids
• In all species, phospholipids are the major lipid
components of spermatozoa, and they contain large
amounts of polyunsaturated fatty acids (PUFAs).
• In the chicken, the PUFA composition in the brain and
retina (phospholipid-rich tissues) also depends on the
PUFA composition in the diet, either directly or via the
egg yolk from which lipids are transferred to the
embryo. As with the brain and the retina, PUFA
deficiency could alter the fatty acid composition of
spermatozoa and their biological functions.
40

41. Effect of dietary fat on semen traits
41

42. Effect of dietary fat on Fatty acid composition
of spermatozoa & seminal plasma
42

43. 43

44. Effect of dietary fats on fertility
• Since the two diets were isolipidic, the difference in
fertility may result from the differences in the n-6/n-3
ratios that were found in both seminal plasma and
spermatozoa.
• The difference in phospholipid fatty acids of spermatozoa
(97% of the fatty acids are in phospholipids) induced by
the diet may have modified the membrane structures,
fluidity, and/or susceptibility to peroxidative damage.
• These modifications may have affected the viability of
the spermatozoa in the female reproductive tract and/or
their fusion capacity, inducing modifications of fertility
rates.
44

45. Distribution of fatty acids of fowl
spermatozoa
• The present data confirm the unique distribution of fatty
acids of fowl spermatozoa compared to that of mammals
and fishes.
• Mainly four major components: 16:0, 18:0, 18:1n-9,
22:4n-6. Whatever the diet, chicken spermatozoa contain
very large amounts of 22:4n-6, the major PUFA, whereas
this fatty acid was not detected in mammalian species or
in trout.
• Moreover, 22:5n-3 and 22:6n-3, which were found in
large amounts in mammalian spermatozoa
45

46. Distribution of fatty acids of fowl
spermatozoa
• It is clear from the present data that the fowl sperm can
incorporate dietary PUFAs, either directly (22:5n-3 and
22:6n-3) or after elongation and desaturation of shorter
precursors (20:4n-6 and 22:4n-6 from 18:2n-6).
• Our data lead us to conclude that:
 1) fowl sperm seem to exhibit a unique fatty acid
composition,
 2) the transfer of essential fatty acids from the diet to the
semen is effective, and
 3) this transfer may have biological effects on the
fertilizing ability of semen. 46

47. 47