Reproductive Impairment Associated With The Ethanolic Extract Of Alstonia Boonei (De-Wild) Stem Bark In Male Rats
G Oze, H Nwanjo, R Oze, E Akubugwo, E Orisakwe, P Aka
astonia boonei stem bark extract, male rats, reproductive impairment
G Oze, H Nwanjo, R Oze, E Akubugwo, E Orisakwe, P Aka. Reproductive Impairment Associated With The Ethanolic Extract Of Alstonia Boonei (De-Wild) Stem Bark In Male Rats. The Internet Journal of Third World Medicine. 2006 Volume 6 Number 1.
The aqueous ethanolic extract of Alstonia boonei stem bark was studied on the reproductive characteristics of 60 male albino rats for 2 and 4 weeks. The rats were randomly assigned to 6 groups of 10 animal each for the 2 weeks segment: group 1 received 1ml/kg normal saline, group II and III got 50 and 200mg/kg of the extracts respectively. For the 4 weeks segment, group IV received 0.5ml/kg normal saline, while groups V and VI got 50 and 200mg/kg of the extract respectively. At the end of the 2 weeks 50mg/kg extract significantly decreased the sperm count, motility, viability and adversely charged the morphology of the sperm. These results were replicated dose and time dependently in the 200mg/kg by the 4th week. However no significant changes on the blood level of testosetorone and body weight were observed. It is concluded from this study that the extract may have toxic potentials on reproductive function without the involvement of plasma testosterone. Thus the dose and duration of application of the extract in folk medicine should be regulated to forestall possible reproductive impairment. The active constituent associated with this effect and the mechanism of action are subjects to further investigation.
The application of natural medicinal products to manage the diseases of man is primordial. Man has often depended on natural substances to treat some ailments, especially in the developing economies. The trend is being reversed in recent times in some advanced countries because of the perceived long term toxicity of some synthetics drugs. Some of the natural products have provided the lead for researches, discovery, development and synthesis of many orthodox drugs in current use; for instance the 4-aminoquinolines for malaria and the cardiac glycoside, digitalis for arrhythmias.
Alstonia boonei grow wild as a lactiferous tree, and belongs to the family, Apocynaceae. It is widely distributed, but thrives best in the tropics and subtroprical regions. Studies reveal that most components of the plant have medicinal values. The phytochemical analysis shows that the plant contains alkaloids, terpenes, sterols and porphyrines. Some of them have been isolated and characterized. They include echitamine, astonine, ditanine, chlorogenine, alstovenine, etc. The pharmacological screening of the plant extract reveals the following actions. Antimalarial antipyretic (Ojewole, 1984); analgesic, antiinflamatory (Kweifio-Okai, 1996, Olajide
Medicinal substances emanating from extracts of Alstonia boonei are widely used in folk medicine, especially in the management of febril illness, pyrexia and malaria syndrome. This informed the study of the plant extract on reproductive function in order to generate information about the possible reproductive effect of the extract, especially in developing economy such as Nigeria where the rural population depend on the extract. The information will also be useful as a guide to folk medicine. practitioners who use the plant extract, regularly.
Materials And Methods
The stem bark of Alstonia bonnie was collected from Imo State University Owerri Campus and was identified by Dr. S. E. Okeke (plant Taxonomist) Department of Plant Biology and Biotechnology, Faculty of Science, Imo State University, Owerri. The voucher specimen is deposited in the departmental herbarium.
Preparation Of Extract
The stem bark was cut into bits and dried in an oven at 50 o c to constant weight. It was Ground into fine powder using Thomas contact mill (Pye, Unipam England) and weighted 405g. The powder was soaked in 7.50L of 70% ethanol for 24hours and extracted with soxhlet. The extract was concentrated using Rotatory Evaporator (Laborato 4000, China). 12.40g of the ethanolic extract was obtained representing 3.06% yield of the dry powder.
Male albino rats weighing 0.1-0.35kg, were obtained from the Animal House, Faculty of Agriculture University of Nigeria, Nsukka. The albino rats were housed in wire mesh cages under standard conditions of temperature and 12 hours light /dark cycle. Animals were fed with commercial diet (Agro feed, Guinea Farms, Nig. Ltd.) and water ad libitum.
The 60 male albino rats were randomly assigned to six study groups (A- F) each containing I0 rats. In addition to the normal feed and water the groups received the following drug extracts by oral tubation:
Group A, 1ml/kg of normal saline for 2 weeks (control).
Group B, 50mg/ kg Alstonia bonnie stem bark extract for 2 weeks.
Group C 200 mg/kg extract for 2 weeks
Group D 1ml/kg of normal saline for four weeks (control).
Group E, 50-mg/kg extract for four weeks.
Group F, 200 mg/kg Alstonia bonnie stem bark extract for four weeks.
Blood Collection And Testosterone Determination
Twenty four hours after the last doses were administered the animals were weighed and then anaesthetized with chloroform vapour, quickly brought out of the jar and sacrificed. Whole blood was collected by cardiac puncture from each animal into clean dry centrifuge tubes without anticoagulant to separate serum. The serum testosterone was estimated with Radio System Laboratory incorporated Kit, Carson, California. This method captured both protein and non- protein – bound testosterone.
Collection Of Spermatozoa
24 hours after the last dose of respective treatments the animals were reweighed and dissected. The sperm specimens were collected by aspiration (Besley
The sperm characteristics were determined using a Neubauer hematocytometer. Ten fields of microscope were randomly selected and sperm motility was assessed on each field (Akbarsha
Legend: The extract did not have any significant effect on the body weight of rats treated for 2 and 4 weeks.
There was no significant difference (P>0.05) in the serum levels of testosterone in rats treated with 50 mg/kg and 200 mg/kg of the extract for 2 and 4 weeks when compared with their control. The serum testosterone levels were 1.2 ± 0.16ng/ml in the control rats; 1.0 ± 0.23 and 1.1 ± 0.20ng/ml respectively in those treated with 50 mg/kg and 200mg/kg of the extract for 2 weeks. Also, the level was 1.46 ± 0.11ng/ml in the control rats; 1.44 ± 0.23 and 1.38 ±25ng/ml respectively in those treated with 50 mg/kg and 200mg/kg of the extract for 4 weeks. The changes in the serum level of testosterone for the two and four weeks segments were marginal and non-significant (P>0.05).
* Statistically different from control (P<0.05)
** Statistically different from control and within group (P<0.05)
*** Statistically different from control but less depressed than 50mg/kg
N Normal percentage morphology
AB Abnormal percentage morphology.
The sperm motility was significantly reduced (p<0.05) in rats treated for 2 weeks with 50 mg/kg. (40.6 ± 4.88) and 200mg/kg. (33.6 ± 0.61) compared with the control (82.0 ± 2.55). Similar significant reduction (P<0.05) was also observed in rats treated for 4 weeks with 50 mg/kg (32.1 ±2.17) and 200 mg/kg (26.0 ±3.10) compared with their controls (61.60 ±1.67). The reduction in motility was more in rats treated for 2 weeks with 200 mg/kg (33.6 ±0.61) compared with those treated with 50 mg/kg (40.6 ±4.88). The effect of extract at 2 weeks was found to be dose dependent (table 3). The inhibition was found to be less for 200mg/kg in the four weeks segment when compared with 50mg/kg. These seemed to be initiation of recovery of the sperm parameters by this time.
The sperm count was significantly reduced (p<0.05) in rats treated for 2 weeks with 50 mg/kg (52.2 ±2.28) and 200 mg/kg. (49.8 ±2.86). No significant reduction (p>0.05) was observed in rats treated for 4 weeks with 50 mg/kg (49.0 ± 2.65) and 200 mg/kg (51.4 ± 2.41) compared with their control (54.8 ± 1.92) (p<0.05). There was also no significant difference in the sperm count of rats treated wit 50 mg/kg for 2 weeks when compared with those treated for 2 weeks with 200 mg/kg. Similar observation were made in those treated for 4 weeks with 50mg/kg and 200 mg/kg (p>0.05).
The sperm viability was significantly reduced (P<0.05) in rats treated for 2 weeks with 50 mg/kg (22.214.171.124) and 200 mg/kg (24.2 ± 0.38) compared with the control (87.4 ±95). Similar reduction (P<0.05) was also observed in rat treated for 4 weeks with 50 mg/kg (44.6±1.67) but not with 200mg/kg (52.4 ± 3.27) compared with their control. The reduction in viability was highest in rats treated for 2 weeks with 200 mg/kg (24.2 ± 0.35) than those treated with 50 mg/kg for the same period (50 ± 3.16). The changes in the sperm viability were both duration and dose dependent (table 3) and statistically significant (p<0.05).
The abnormalities of the epididymal sperm morphology observed were too long tails, tiny and small tails, double head and biforcal tails. The degree of morphological abnormality expressed as percentage was significant (p<0.05). The morphology of rats treated with 200mg/kg for 4 weeks (72.6 ±5.27) exhibitd higher percentage abnormality than those treated with 50 mg/kg extract for 4 weeks (57.4 ±9.94). The abnormalities in morphology of the sperms were both dose and duration dependent (Table 3).
Spermatozoa posses two vital features: motility and fertility. The quantity and quality of the sperm are determined by the sperm-count, the degree of motility, viability and morphology. Some plant extracts such as Ocimum sanctum, Amaranthus spinosus, Carica papaya and Spirulina plantensis have been reported to affect spermatic qualities (Murugavel
The present study evaluated the reproductive impairment caused by extract of the stem bark of Alstonia boonei at two and four weeks duration. The results from the 4 weeks segment showed that there were changes in the body weights of the animals, though these were not significant (p>0.05). Changes in body or organ weights after chemical or drug administration is an indication of possible toxicity (Laumann
The serum testosterone level also decreased marginally when the test groups B,C, E and F were compared with their respective control groups A and D in the 2 nd and 4 th week segments. Peripheral testosterone concentration are known to affect mainly testicular secretary function (Jubiz
Fifty and 200mg/kg of the plant extract in a two weeks study period significantly reduced the sperm count, percentage motility, viability and normal morphology (p<0.05) (Table 3), this agrees with the work of Yinusa
Some species of Alstonia such as A. Scholaris and A.spectabilis (Apocynaceae) have been shown to inhibit the release of nitric oxide (NO) in cell culture. (Choi and Hwang, 2005). Nitric oxide is known to be a potent vasodilator and smooth muscle relaxant. Its inhibition may lead to vasoconstriction, hypertrophy, ischemia, and necrosis of the reproductive cells. The result of the present study may not be unconnected with such metabolic interference in NO release. This action could have deleterious effect on the spermatocytes and reproductive characteristics of the male rats.
It is therefore concluded that A. boonei stem bark extract induced testicular damage at the tested doses and duration. The reduction in sperm count, attenuation of motility, viability and the adverse changes in the cyto- architecture of the germ cells may negatively impact on fertility in the male rats. However, there are reports where the natural agent are selectively toxic to the mammalian tissues while sparing the rodents because they posses more efficient xenobiotic biotransformation system (Laumann