INTRODUCTION
Plants have been known as natural
sources of fertility enhancing substances. [1] Since the dawn of
human existence, infertility has remained a major medical and social
preoccupation. For ages now, couples have been more concerned with conception
and its difficulties.[2] Infertility
is the inability to conceive after
having regular unprotected sex. In African tradition, infertility is always
considered to be a women’s fault. However, medical evidence has shown that both
genders have equal rates of infertility. Male infertility can be due to many
factors including but not limited to erectile dysfunction, poor libido,
psychological challenges, poor hormonal levels and poor sperm quality (low sperm
count, abnormal morphology and sluggish sperm cells) due to high level of oxidative
stress.
Although there are
many established treatment plans for male infertility, they are either very
expensive (like hormonal therapies and medications) or highly invasive like
surgeries.[3] In order to tackle this disorder, there is therefore
the need to resort to methods that are not only less expensive, but are also
non-invasive. These methods include using plants
or herbs that have medicinal values. The world health organization (WHO) has
estimated that 80 percent population of some countries presently uses herbs for
some aspect of primary health care. It has also been established that about 25
percent of new medicines in the United States are obtained from plants.
[4] Plants
with medicinal value have been extensively used to improve or regulate
fertility in males. This is because medicinal plants have several
beneficial effects on male fertility which include increased sexual desire
(libido), [5, 6, 7] stimulatory activity of hormones, [8, 9]
increased semen volume, increased sperm count and increased viability and sperm
motility.
The preference of herbal medicine to synthetic treatments may be because
of the belief that they have less or no side effects, have high nutritional
value and are relatively cheaper. [3] Most of these medicinal
plants are leafy vegetables or fruits and can be easily found around us and
form important components of our daily diets. A substantial number of them also
contain flavonoids, saponins, tannins, alkaloids and
many other constituents known to have fertility boosting effects.
The S.
aethiopicum (garden egg) is a very common
vegetable, which is mainly grown because of its leaves and fruits. The fruits
and leaves of S. aethiopicum can be eaten in so many forms such as fresh
state, steamed, juiced, pickled or boiled. The
leaves can also be used in preparing stews or soups
This study was
therefore aimed at establishing the effect of the consumption of Solanium aethiopicum fruit
on male fertility, through the evaluation of its effect on the serum
concentration of the gonadotropic hormones (FSH and LH), Testosterone,
Prolactin, sperm parameters and the histology of the testis.
MATERIALS
AND METHODS
A total of 32 adult male Wistar
rats with average weight of 250g were used for this study. The animals were
procured from the animal care unit of Human Physiology Department of the University
of Port Harcourt. These animals were housed in an environment of normal room
temperature separately and were fed with standard finisher feeds (Top feed,
Nigeria) and water for 14 days for acclimatization after which they were used
for the experiment. The Solanum aethiopicum
fruit used for this study was bought from a farm located at Omuokiri,
Aluu in Port Harcourt, Rivers state and sent to the
Department of Pharmacognosy and Phytotherapy,
Faculty of Pharmaceutical Sciences of the University of Port Harcourt for
identification and authentication, with voucher Number (UPHS0474). The
identified fruits were washed and then ground fresh to form a paste. The
maceration method was used for the extraction. About 1500 grams of the fruit of
the plant after weighing were dissolved in 80% ethanol and 20% water, making up
to 2000ml of Hydroethanol, for 72 hours in an
extraction vessel well-kept in an air light cupboard. During the period of
maceration, it was well shaken three times daily to ensure a proper absorption.
The filtration was done using a glass funnel, 1000ml beaker and Whitman filter
paper. The funnel was placed in the beaker. The filtrate was carefully poured
into the funnel which filters through the funnel into the beaker. The
extraction after filtration was dried using a rotary evaporator which separates
the solvent from extract leaving it in a liquid form, which was then completely
dried on a steam bath with a temperature of 45şc.
The thirty-two (32)
male Wistar rats used for this study were grouped
into four (4) groups with each group containing eight (8) rats as shown in the
table below.
RESULTS
Table 2:
Effects of Solanum aethiopicum
fruit extract on Reproductive Hormones.
|
Groups
|
FSH (miu/ml)
|
LH (miu/ml)
|
Prolactin (ng/ml)
|
TESTOSTERONE (ng/ml)
|
|
1 (control)
|
1.60±0.42
|
1.60±0.35
|
2.03±0.23
|
0.83±0.30
|
|
2 (100mg/kg)
|
3.37±0.27 *
|
3.50 ±0.35
|
2.40±0.26
|
1.63±0.18 *
|
|
3 (200mg/kg)
|
4.23±0.15 *
|
4.73±0.30 *
|
4.70±0.45
|
1.93±0.07 *
|
|
4 (300mg/kg)
|
4.47±0.27*
|
4.87±0.41*
|
4.77±0.38
|
2.60±0.25*
|
Data are
expressed as Mean ± SEM of 5 rats, * represents significant differences
relative to the control at p<0.05.
Table 3:
Effects of Solanum aethiopicum
fruit extract on Sperm parameters.
|
Sperm
parameters/ Groups
|
Normal
morphology (%)
|
Sperm
viability (%)
|
Sperm count (Million/ml)
|
Sperm motility (%)
|
|
1 (control)
|
93.0±1.53
|
66.7±4.41
|
55.0±5.69
|
78.3±10.14
|
|
2
(100mg/kg)
|
94.3±1.20
|
90.0±2.89*
|
67.3±10.53
|
94.7±2.60
|
|
3 (200mg/kg)
|
95.7±1.76
|
95.0±2.89*
|
76.3±14.84.
|
97.7±1.20*
|
|
4
(300mg/kg)
|
96.0±3.06
|
97.7.±1.45*
|
80.67±12.96*
|
98.7±1.33*
|
Data are expressed
as Mean ± SEM of 5 rats, * represents significant differences relative to the
control at p<0.05.
Plate 1:
Photomicrograph of a section of the testis of rat of control group after 30
days period. It reveals: (a) A histologically normal testis with:
(a)
Normally shaped seminiferous tubules containing spermatogonia
(SPG), spermatocytes (SPC) and spermatozoa (SPZ), surrounded by intact basement
membrane (BM).
(b)
Interstitial spaces (ISS) containing Leydig cells
Stain: H
& E. Magnification: X 400.
Plate 2:
Photomicrograph of a section of the testis of rat of group 2 (100mg/kg of Solanum aethiopicum
fruit extract) after 30 days period. It reveals a
histologically normal testis with (a) Intact
seminiferous tubules containing SPG, SPC and SPZ
(b)
Interstitial spaces (ISS) containing Leydig cells
Stain: H
& E. Magnification: X 400.
Plate 3:
Photomicrograph of a section of the testis of rat of group 3 (200mg/kg of Solanum aethiopicum fruit
extract) after 30 days period. It reveals a histologically normal testis with
(a) Intact seminiferous tubules containing SPG, SPC
and SPZ
(b)
Interstitial spaces (ISS) containing Leydig cells
Stain: H
& E. Magnification: X 400.
Plate 4:
Photomicrograph of a section of the testis of rat of group 4 (300mg/kg of Solanum aethiopicum fruit
extract) after 30 days period. It reveals a histologically normal testis with
(a) Intact seminiferous tubules containing SPG, SPC
and SPZ
(b)
Interstitial spaces (ISS) containing Leydig cells
Stain: H
& E. Magnification: X 400.
DISCUSSION OF
FINDINGS
Effect
of Hydroethanolic fruit extract of S. aethiopicum on Reproductive Hormones
The study revealed
that after 30 days of administration of 100 mg/kg, 200 mg/kg and 300mg/kg of S.
aethiopicum fruit extract, there was a
statistically significant increase in the serum concentrations of Luteinizing
Hormone (LH), Follicle Stimulating Hormone (FSH) and Testosterone (TET) while
there was no significant change in the concentration of Prolactin (table 2). This
elevated level in the concentration of the male reproductive hormones caused by
the extract could be attributed to the presence of saponins
which reportedly helps in improving testosterone levels and flavonoid which
improves androgen levels. [11]
The principal
hormones regulating fertility in males are Luteinizing hormone (LH) and
Follicle stimulating hormone (FSH). Follicle stimulating hormone principally
stimulates the production of spermatogonia to
spermatocytes and also maintains the spermatogenic
process. Both follicle stimulating hormone and Luteinizing hormone are
necessary for meiosis and development of spermatids. Testosterone has been
found to be the main male gonadal hormone produced by the interstitial cells of
Leydig of the testis. In addition to LH and FSH,
testosterone is the major hormonal marker of androgenecity.
It is principally concerned with the growth, development and maintenance of
male reproductive organs. [12] In association with FSH, testosterone
acts on the seminiferous tubules to initiate and maintain spermatogenesis.
[13]
The statistically significant
elevation in the concentration of FSH therefore suggests that the S.aethiopicum
fruit has a stimulatory action on the hypothalamic-pituitary axis. The
pro-gonadotropic action by the extract indicates that it may enhance the normal
functioning of the Sertoli cells which will increase
sperm cell maturation. The statistically significant elevation in the
concentrations of the gonadotropic hormones in all the experimental groups
suggests a direct action on the anterior pituitary hormongenesis.
These
findings of this research agree with the studies on the fertility effects of
other plant extract (Allium sativum) by other
researchers who reported that saponins, flavonoids,
alkaloids and tannins present in plant extracts have the capability of increasing
the body’s natural Testosterone, LH and FSH levels. [13] Luteinizing
hormone which is released by the pituitary gland has been found to help in
maintaining testosterone levels. [14] This
therefore implies that the observed increase in Luteinizing hormone level may
be responsible for the increase in testosterone concentration which enhances
male fertility.
Effect of Hydro-ethanolic fruit extract of S. aethiopicum
on Sperm Parameters
Table 3
reveals the action of the various dosages of the fruit on sperm parameters. It
shows that there was a statistically significant elevation in the percentage of
sperm viability and motility in most of the experimental groups with respect to
the control group. There was also a statistically significant elevation in
sperm count in the experimental group with the highest extract dose with
respect to the control group while there was no significant change in the
percentage of cells with normal morphology with respect to the control. Sperm
count, motility, viability and morphology are usually evaluated to determine
the fertility of a male subject. The enhancing action of the fruit on sperm
characteristics could be attributable to favourable
and increased spermatogenic activities in all the
experimental groups. Increase in the epididymal sperm
count as observed in this study may be associated with testosterone increase.
The testis performs two major functions: Steroidogenesis
and spermatogenesis (production of testosterone and maintaining
spermatogenesis). It does this through coordination between various cell types,
including Sertoli, Leydig
and germ cells. [11] Testosterone regulates spermatogenesis in males
through phosphorylation of cAMP response
element-binding protein (CREB) and its increase has been associated with
improvement in sperm quantity and quality. [12] The statistically
significant increase in sperm count in the experimental groups in relation to
the control group could be ascribed to the importance of Solanum aethiopicum as a potent antioxidant and
free radical scavenger. [13]. This finding corroborates with the
work of others which established that potent antioxidants ameliorate increased
free radicals generated by both natural and experimental stress, thereby
causing a substantial elevation in the spermatogenic
activity by increasing the production of testosterone from the Leydig cells.[14]
This result also agrees with the finding of the research done by
others on the testes of male Wistar rats with mercury
chloride induced toxicity treated with S.
melongena fruits. [15]
Luteinizing hormone reportedly induces testosterone secretion from the
interstitial cells of Leydig of the testes which in
turn is also required for the growth and development of male reproductive
organs [16] and in association with FSH, acts on the seminiferous
tubules to initiate and maintain spermatogenesis. [17]
This finding of this research therefore indicates that S. aethiopicum
is capable of increasing serum levels of testosterone and further suggest that
it could have a positive impact on testicular androgen secretory function which
promotes maintenance of spermatogenesis.
Effect of
administration of Hydro-ethanolic fruit extract of S.
aethiopicum on the Histology of the Testes
The histology of the testes in all the
experimental groups after 30 days of extract administration revealed a normal
histology in comparison with the control. This suggests that the fruit extract
of S. aethiopicum
may have a protective effect on the testis thereby promoting fertility.
This protective effect on the testis may be attributed to the presence of
flavonoid in the fruit extract which has been found to possess cyto-protective activities. It has also been found that flavonoids
are effective in the prevention of lesion and in the scavenging of free
radicals, generated by natural and experimental stress that may damage
testicular cell structure. [18]
CONCLUSION
The study showed that the hydroethanolic
fruit extract of Solanum aethiopicum
caused a significant dose dependent increase in the serum concentration of male
reproductive hormones (FSH, LH and Testosterone) such as Follicle stimulating
hormones, luteinizing hormone and Testosterone. There was also a significant elevation
in the percentage sperm motility and percentage of viable sperm cells in
relation to the control. It was also found to be capable of protecting or
preserving the cytoarchitecture of the testis. These
results show that the continous intake or consumption
of the fruit of Solanum aethiopicum
(garden egg) may increase the concentration of reproduction hormones and cause
an appreciable improvement in sperm parameters in male wistar
rats and therefore capable of boosting their reproductive potential.
COMPETING
INTERESTS
No competing interests exist.
AUTHOR’S
CONTRIBUTIONS
Author Zabbey VZ
conceived the study, designed the protocol and contributed in writing the
manuscript, authors Adienbo OM and Dapper DV
coordinated the experiment, performed the laboratory procedures and contributed
in writing the manuscript while author Ojeka SO
performed the statistical analysis, data interpretation and also contributed in
the manuscript writing. The authors have all read through and approved the
final manuscript.
ACKNOWLEDGEMENTS
The authors would like to express warm
appreciation to Dr Suleiman from the Department of Pharmacognosy and Phytotherapy,
Faculty of Pharmaceutical Sciences, University of Port Harcourt, for his
contribution in the identification and authentication of the plant.
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