Introduction

Malaria remains one of the world's most significant health problems despite increasing research and control efforts₁. Over two billion people are at risk of infection, over a quarter of a billion cases are thought to occur annually, and at least a million people die every year as a result of the disease, alone or in combination with other conditions. The disease is estimated to be responsible for an annual loss of around 0.5 to 1% of gross domestic product in countries where it is endemic₂. The occurrence of malaria during pregnancy exposes the mother and infants to serious risks. It is therefore imperative that pregnant women be protected against malaria; and that pregnant women with malaria receive treatment as soon as possible₃.

Artesunate is one of the numerous drugs for malaria intervention in Nigeria. It is a semi synthetic derivative of artemisinin, the active compound of the Chinese herb Artemisia annua which consist of the sodium succinyl salt of dehyroartemisinin₃. Artemisinin-type compounds reduce malaria parasitemia more rapidly than any other known antimalarial drugs and are effective against multi drug resistant malaria parasites₄,₅. Artesunate is highly effective against multi-drug resistant strains of plasmodium falciparum hence its increasingly wide usage for the treatment and management of malaria₆. Artesunate is well tolerated at therapeutic doses; therefore a lot of people, pregnant women inclusive take the drug.

Several studies have shown that high doses of artesunate can produce neurotoxicity such as selective damage to brainstem centres in mice and rats₇,₈,₉. Artesunate have been reported to cause gait disturbances, loss of spinal cord and pain response mechanisms in animals₁₀,₁₁.

The stomach, a distensible organ located in the abdominal cavity, functions in the degradation and digestion of food materials in the body. It also prevents gastric ulceration due to the presence of numerous mucous secreting glands₁₂.

The effects of artesunate on the stomach may not have been documented, but there have been reports that it may be implicated in varied symptoms of nausea, vomiting, diarrhea and abdominal pain. This present study was to elucidate the histological effects of artesunate on the stomach of adult Wistar rats.

Materials And Methods

The present study was registered and given due approval for the methodology therein by the ethical review committee of the University of Benin, Benin City as stipulated by the Nigerian Health Research Ethics Committee.

Animals: Twenty-four (24) adult Wistar rats of both sexes with average weight of 210g were randomly assigned into four groups A, B, C and D of (n=6) in each group. Groups A, B, and C of (n=18) serves as treatments groups while group D (n=6) is the control. The rats were obtained and maintained in the Animal holdings of the Department of Anatomy, School of Basic Medical Sciences, University of Benin, Benin city, Nigeria. They were fed with growers' mash obtained from Edo feed and flour mill limited, Ewu, Edo state, and were given water liberally. The rats were allowed to gain maximum acclimatization before the actual commencement of the experiment. The Artesunate tablets were obtained from the University of Benin Teaching Hospital Pharmacy, Benin City, Edo state, Nigeria.

Artesunate Administration: The rats in the treatment groups (A, B, & C) received 4mg/kg body weight of Artesunate base dissolved in distilled water for the first day. Animals in the treatment group ‘A' continued with this dosage for the next two days, while animals in groups B & C received 2mg/kg once daily for six and thirteen days respectively. The control group D received equal volume of distilled water through orogastric tube. The treated rats in groups A, B, and C were sacrificed by cervical dislocation on the 4th, 8th and 15th day of the experiment respectively, while that of the control group D was sacrificed at the end of the experiment. The abdominal region was opened to expose the abdominal visceral. The stomach was quickly dissected out and fixed in 10% formal saline for routine histological techniques.

Histological Study: The tissue was dehydrated in an ascending grade of alcohol (ethanol), cleared in xylene and embedded in paraffin wax. Serial sections of 7 microns thick were obtained using a rotatory microtome. Some of the deparaffinized sections were stained routinely with haematoxyline and eosin (H&E) method₁₃. The digital photomicrographs of the desired sections were made in the Department of Anatomy research laboratory, University of Benin, Nigeria for further observations.

Results

The sections of stomach from the controls showed normal histological features with distinct highly packed glandular secretory mucosa of the stomach and presence of vacuolations in the sections (Figure 1).

The sections of the stomach from the treatment (A, B, & C) groups showed some varying degree of degenerative and necrotic changes, and cellular hypertrophy. There were marked intercellular vacuolations appearing in the stroma and distortions in the epithelia and glandular cells of the stomach (Figure 2, 3 &4).

Figure 1

Figure 1 (GROUP D): Control section of the stomach (Mag. x400).

Figure 2

Figure 2 (GROUP A): Treatment section of the stomach (group A) that received 4mg/kg of artesunate for 3 days, (Mag. x400)

Figure 3

Figure 3 (GROUP B): Treatment section of the stomach (group B) that received 4mg/kg 1st day and thereafter 2mg/kg for 6 days of artesunate. (Mag.x400)

Figure 4

Figure 4 (GROUP C): Treatment section of the stomach (group C), that received 4mg/kg 1st day and thereafter 2mg/kg for 13 days of artesunate. (Mag. x400)

Discussion

The results (H & E) revealed that administration of artesunate showed some degenerative and necrotic changes, cellular hypertrophy, and increase intercellular vacuolations which appeared in the stroma of the treatment groups compared to the control section of the stomach. Degenerative changes have been reported to result in cell death, which is of two types, namely apoptotic and necrotic cell death. These two types differ morphologically and biochemically₁₄. Pathological or accidental cell death is regarded as necrotic and could result from extrinsic insults to the cell such as osmotic, thermal, toxic and traumatic effects₁₅.

The process of cellular necrosis involves disruption of the membranes structural and functional integrity. Cellular necrosis is not induced by stimuli intrinsic to the cells as in programmed cell death (PCD), but by an abrupt environmental perturbation and departure from the normal physiological conditions₁₆. There is the need to further investigate the actual mechanism by which artesunate induced cellular degeneration in the stomach of adult Wistar rat in this study.

In this study artesunate may have acted as toxin to the cells of the stomach, affecting their cellular integrity and causing defect in membrane permeability and cell volume homeostasis. In cellular necrosis, the rate of progression depends on the severity of the environmental insults. The greater the severity of the insults the more rapid the progression of neuronal injury.₁₇ The principle holds true for toxicological insult to the brain and other organs₁₆. It is inferred from this results that prolonged and high dose of artesunate resulted in increased toxic effects on the stomach.

The vacuolations observed in the stroma of the stomach in this experiment may be due to artesunate interference. The cellular hypertrophy observed in this experiment may be due to the adverse effects of artesunate on the stomach. This study may underlie the possible gastrointestinal symptoms such as nausea, vomiting and abdominal pains.

Conclusion

Our study revealed that high doses and long term administration of artesunate causes degenerative and necrotic changes, cellular hypertrophy, and increase intercellular vacuolations in the stomach of adult Wistar rats. These results may probably affect the functions of the stomach and may lead to gastric ulceration in adult Wistar rats.

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