Prevention of radiation-induced hepatic damge on swiss albino mice by aloe vera leaf extract

Discussion
In the present study, after exposure to 6 Gy gamma radiations to animals resulted in radiation sickness within 3-5 days after exposure. The symptoms included reduction in the food and water intake, weight loss, diarrhea, ruffling of hairs and irritability. The similar symptoms have been observed in mice after gamma irradiation by others also [17, 18].
Liver is the primary organ of drug metabolism. It plays a key role of detoxification agency in the body. Any damage to this organ may cause serious disorders in the form of various diseases, which can be observed in the form of histopathological and biochemical lesions. Therefore, the present study has been targeted on liver to evaluate radiation induced biochemical lesions and the radioprotective potential of the leaf extract of plant Aloe vera in gamma irradiated mice.
An increase in the liver phosphatase activity of mice due to irradiation was observed in the present study. Similar increase in such enzymes was observed earlier after exposure of mice or rats with various doses [19]. Aikman and wills [20] suggested that lesions are produced in the membrane lipids due to irradiation possibly buy peroxides , which lead to the activation of latent acid hydrolases , that could result in the digestion of the membrane itself, with the consequent activation and release of the other lysosmal enzymes , in the present study . It was observed that after AVE administration radiation-induced increase in ACP was found to be significantly of lower degree. Hamdy et al. [21] observed protection of acid phosphatase, when solutions of lysosomal enzymes were exposed to high doses of radiation containing cysteine and 4-aminoaphthal. Nam [22] too observed significant protection against rise in of serum acid phosphatase at 6 and 130 hrs, if methylene blue was injected to rats prior to irradiation with 360 R. Bhartiya and Khan [23] also found an increase in ACP activity in mice after exposure to different doses of radiation.
A rise in ALP activity in liver after gamma exposure, as evident in present experiment, is quite similar to early reports Khan et al. [24]. ACP and ALP are the enzymes, concerned with biosynthesis of fibrous proteins [25] and mucopolysaccharides [26]. They also act as the hydrolytic enzymes which play an important role in dissolution of dead cells of the body [27]. Radiation –induced cell death may be a possible reason for increased activity of ACP and ALP. Post-irradiation damage to liver is another reason attributing to increased level of ACP and ALP. Radiation –induced stress also accounts for an increased activity of these enzymes as observed in the present study. It has been observed that AVE provided protection by exhibiting a significant decrease against radiation-induced increase in ACP as well ALP at various periods of study in experimental animals compared with respective controls. Similar increase in such enzymes was observed earlier [28].
The ALP activity in KB cells increased upon treatment with aloe-emodin when compared to controls was observed. Samarth et al. [29] reported that the activity of ACP increased and ALP decreased in Mentha piperita treated irradiated mice.

Aloe barbadensis Mill has been used in variety of disease in traditional Indian system of medicine in India and its used for hepatic ailments is also documented. In the present study an attempt s been made to validate its hepatoprotective activity. This is in good accordance with the studies of aqueous extract of Aloe barbadensis is significantly capable of restoring integrity of hepatocytes indicated by improvement in physiological parameters, excretory capacity (BSP retention) of hepatocytes and also by stimulation of bile flow secretion [30].
Ionizing radiation induces lipid peroxidation (LPx) which can lead to DNA damage and cell death [31, 32]. Therefore, an agent that protects against such damage can provide protection against radiation injury. The administration of AVE before irradiation significantly reduced the amount of LPx compared to the control group. The inhibition of LPx by AVE may also have been responsible for the observed radioprotection.
Earlier reports with same animal model also proved that Aloe vera is a good radioprotection against mouse intestinal mucosa after low level (0.5 Gy) exposure to gamma radiation [33].
An increase in the glutathione (GSH) level by AVE may be responsible for the scavenging of radiation-induced free radicals including LPx and thereby protecting against radiation-induced mortality. It has been reported that LPx starts to increase as soon as the endogenous GSH is exhausted, and the addition of GSH promptly stops further peroxidation [34]. The AVE is found effective in altering the sensitivity to radiation possibly by protecting the biological molecules against radiation-induced oxidation of water by decreasing the oxygen tension in the organism.