| Summary: | Thesis (MScMedSc)-- Stellenbosch University, 2013. === ENGLISH ABSTRACT: Much has been documented about the detrimental effects of adverse lifestyle factor
exposure on the body. Exposure to factors, such as cigarette smoke, have proved to not
only be a burden on global health and economy, but have also led to growing concerns
about effects on systemic functions such as reproduction. The aim of the present study was
to determine the effects of in utero and in vitro nicotine exposure on spermatozoal function
and the antioxidant enzyme activity and lipid peroxidation (LPO) status of the male
reproductive system. A better understanding of this process is necessary to combat the
respective burdens of smoking and male infertility and for the prospective development of
treatment strategies.
Two experimental models were employed: Wistar rats were exposed to nicotine in utero
while human and rat spermatozoa were exposed to nicotine in vitro. In utero studies were
achieved by selecting healthy pregnant rats and treating them with 1 mg/kg-bodyweight/day
nicotine or 1 ml/kg-bodyweight/day 0.85% physiologic saline throughout gestation and
lactation. Male rat pups were selected and sacrificed at each of the following age groups
(n=6): 42 days, 84 days and 168 days old. The pups were only exposed to the
treatment/saline via placental uptake or lactation. Biochemical analyses of the tissue
comprised of measurement of LPO and antioxidant enzyme activity. Results indicated a
significant association of maternal nicotine exposure to decreased levels of primary
antioxidant enzymes in rat testes. Of particular note was the observation that the treatment
group, of which each of the respective antioxidant enzyme levels were significantly less than
the control group, was the oldest (d168) rat group.
In vitro studies were achieved by collecting sperm samples from healthy human donors
(n=12), healthy rats (n=6) and obese rats (n=6). Samples were washed and exposed to
different concentrations of high levels of nicotine (Control, 0.1mM, 1mM, 5mM, 10mM) in
vitro. Semen parameters such as motility, viability and acrosome reaction were monitored at
different time points (30min, 60min, 120min, 180min). Results revealed increasing in vitro nicotine concentrations were associated with decreased viability and acrosomal status of
human spermatozoa and decreased progressive motility and viability of rat spermatozoa.
Obesity was also associated with decreases in progressive motility and viability of rat
spermatozoa.
These results indicate that the acute in vitro exposure of spermatozoa to high levels of
nicotine could adversely affect semen quality and may be an additive factor to the
impediment of male fertility. In utero results reveal maternal nicotine exposure adversely
affects male fertility in later life and seems to elicit more detrimental effects on the
reproductive system than that of direct nicotine exposure to spermatozoa. Obesity also
inhibits parameters of male fertility and these effects are exacerbated by nicotine exposure.
The authors believe these adverse effects on the reproductive system to be related to an
increased activation of leukocytes, excess production in reactive oxygen species (ROS) and
consequent onset of oxidative stress (OS). Nevertheless this study agrees with other studies
that nicotine exposure may be an additive factor to the impediment of male fertility. === AFRIKAANSE OPSOMMING: Daar is reeds baie bekend oor die moontlik newe effekte vir die liggaam wat met ‘n
ongesonde lewenstyl gepaard gaan. Menslike blootstelling aan sulke faktore, soos sigaret
rook, is wêreldwyd ‘n las vir gesondheid en ekonomie en het gelei tot geweldige kommer
onder navorsers oor die moontlike komplikasies vir liggaamlike funksies soos voortplanting.
Die doel van die betrokke projek was om die effekte van in utero en in vivo nikotien
blootstelling op die antioksiderende ensiem aktiwiteit en lipied peroksidasie status van
reproduktiewe weefsel en die funksionele parameters van spermatozoa te bepaal. ‘n Beter
begrip van hierdie proses is noodsaaklik om die las van rook en vetsug teen te werk en vir
die moontlike ontwikkeling van behandelingsstrategieë.
Twee eksperimentele modelle is ontwerp: Wistar rotte is in utero blootgestel aan nikotien
terwyl mens- en rot- spermatosoë ook in vitro aan nikotien blootgestel is. Vir die in utero
studie is gesonde dragtige rotte gedurende swangerskap en laktasie met 1 mg/kgliggaamsgewig/
dag nikotien of 1 ml/kg-liggaamsgewig/dag 0.85% fisiologiese soutoplossing
behandel. Manlike welpies is gekies en geoffer op elk van die volgende ouderdomme (n=6):
42 dae, 84 dae en 168 dae. Die welpies is slegs aan nikotien blootgestel deur plasentale
opname en laktasie. Biochemiese analise van die testikulêre weefsel het ‘n beduidende
assosiasie getoon tussen maternale nikotien blootstelling en verminderde vlakke van die
primêre antioksiderende ensieme. Die 168 dag oue groep het ‘n merkbare vermindering
getoon tussen kontrole en nikotien weefsel vir elk van die antioksiderende ensieme.
Vir die in vitro studie is sperm monsters verkry vanaf gesonde mans (n=12), gesonde rotte
(n=6) en vet rotte (n=6). Monsters is gewas en in vitro blootgestel aan verskeie hoë vlakke
van nikotien (kontrole, 0.1mM, 1mM, 5mM, 10mM). Seminale parameters soos motiliteit,
lewensvatbaarheid en akrosoom status is by verskei tydpunte gemeet (30min, 60min,
120min, 180min). Dit blyk dat verhoging in in vitro nikotien konsentrasies verband hou met
verlaagde lewensvatbaarheid en akrosoom status van menslike spermatosoë en verlaagde
progressiewe motilteit en lewensvatbaarheid van rot spermatosoë. Vetsug is ook geassosieer met verlagings in progressiewe beweeglikheid en lewensvatbaarheid van rot
spermatosoë.
In utero resultate openbaar dat maternale nikotien blootstelling manlike vrugbaarheid nadelig
beïnvloed in latere lewe en blyk dat dit meer van ‘n nadelige uitwerking op die
voortplantingstelsel het as dié van direkte nikotien blootstelling aan spermatosoë. In vitro
blootstelling van spermatosoë aan hoë vlakke van nikotien, het wel ook semen kwaliteit
nadelig beïnvloed. Vetsug inhibeer ook manlike vrugbaarheids parameters en hierdie effek
word vererger deur nikotien blootstelling.
Die outeure glo dat hierdie nadelige uitwerking op die voortplantingstelsel verband hou met
'n verhoogde aktivering van leukosiete, oortollige produksie van reaktiewe suurstof spesies
en die gevolglike aanvang van oksidatiewe stres bevorder. Hierdie studie stem wel ooreen
met ander studies wat nikotien blootstelling bestempel as ‘n bydraende faktor tot die
struikelblok van manlike onvrugbaarheid. === Harry Crossley Foundation (South Africa)
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