The use of CP has been limited due to its adverse effects on different organs. Previous studies confirmed that CP has severe deleterious side effects on pregnant mothers and their fetuses [40,41]. On the other side, several researches emphasized that carrot flavor like garlic and several other flavors are transmitted from the nursing mother’s diet to her milk [42]. Accordingly, the current work was mainly designed to evaluate the protective effect of garlic extract against CP-iduced nephrotoxicity in pregnant mother rats and their offsprings.
The obtained results of the current study revealed a remarkable significant decrease in the final body weight of CP-treated mother rats and their offsprings if compared with control. This result came in accordance with findings of previous studies [43,44] who recorded a significant reduction in the body weight of CP-treated rats after 3–5 days post single I.P injection of 5–7.5 mg/kg of CP. The reduction of the body weight in CP-treated rats might be in part attributed to the direct toxic effect of CP on renal tubules that caused reduction in water reabsorption and excessive sodium excretion with subsequent polyuria, dehydration and reduction of body weight [45, 46]. Another study postulated that the reduction in body weight in CP treated rats might be due to gastrointestinal toxicity with subsequent decrease in appetite, ingestion and assimilation of food [48]. The reduction in body weight of offspring which their mothers received CP may be attributed to excretion of CP metabolites in milk during breast feeding. On the other side, an obvious gain in the body weight was noticed in post-treatment of CP treated -mother rats with garlic extract. Nasr and Saleh reported that garlic extract can maintain the body weight through regulation of renal and intestinal enzyme functions [33]. Other studies revealed that, infants whose mothers consumed carrot during pregnancy and breastfeeding periods accepted carrot-flavored cereals more readily than infants who were exposed to this flavor for the first time [48]. Further study assumed that, ingestion of garlic by pregnant women leads to longer breast attachment for their infants [49]. In contrast to obtained result concerning body weight, Dixit and Joshi was recorded a significant decrease in body weight after treatment with a garlic powder preparation by daily gavage [50]. Such conflicting results may be attributed to the difference in exposed dose of garlic as well as the conditions of experiment.
In the current work, deleterious histological changes were recorded in the renal cortex of CP-treated mother rats and their offsprings. Such changes included atrophied glomeruli, dilatation of Bowman’s space, degeneration, necrosis and detachment of the proximal tubular epithelial cell lining, dilated tubular lumina of both proximal and distal tubules. This could be due to the cytotoxic effect of CP. Similar observations were recorded in rats exposed to different doses of CP [51,52]. Aydogan et al. postulated that CP has a direct toxic effect on the glomerular and tubular structures through the generation of reactive oxygen species (ROS) that induces necrosis in renal tubular cells [53]. The nephrotoxicity induced by CP in childhood cancer therapy has been demonstrated for some time, while new aspects of the tubular damage, including increased elimination of low molecular weight peptides and reduced excretion of some glycoprotein protein [54]. Early data on CP-induced nephrotoxicity indicated that 25% of patients have an elevation in blood nitrogen levels following 1 or 2 weeks of treatment which is considered as a main cause for glomerular and tubular damage [55]. Pinta and Lippard suggested that, the accumulation of toxic platinum metabolites of CP inside renal tubule cells seems to be one of the most important factors implicated in induction of nephrotoxicity [56]. Other study concluded that frequent doses of CP can directly injure the renal tubules, renal vasculature, and glomeruli through induction of oxidative stress, inflammation and apoptosis [57].
In the present study, a remarkable improvement was recorded in the renal tissues of mother rats administrated with garlic after treatment with CP. Several studies have demonstrated that garlic extract prevents the oxidative stress and exerts a protective effect against different toxic agents through its powerful antioxidant and free radical scavengers [58, 59]. Other studies revealed that garlic has a powerful cytoprotective effects to the cells of vital body organs [60, 61].
Serum creatinine and urea levels are considered the main biomarkers that efficiently determine the glomerular filtration rate [46]. In the present study, nephrotoxicity of CP was evident from the elevated levels of serum urea and creatinine in mother rats and their offspring. Similar observations were previously reported in several studies [45, 47]. Motegi et al. reported that, use of CP by pregnant women can exhibit a reversible elevation of serum creatinine and urea of her neonates [62]. The elevation in the serum levels of these renal biomarkers might be attributed to the impaired renal functions [58], tubular obstruction and cytotoxicity of the renal tubules cells [46]. Several studies postulated that the disturbance in renal functions by CP is mainly due to its ability to inhibit protein synthesis in the tubular cells [63], or to initiate lipid peroxidation and generate free radicals in renal tubules [64]. Aydogan et al. added that the elevation in the renal biomarkers was due to the direct cytotoxic effect of CP on the glomerular and tubular structures through the generation of ROS [53].
In the present study, administration of CP followed by garlic extract revealed obvious recovery in the levels of serum creatinine and urea that markedly elevated by treatment of CP alone. This could be attributed to a cytoprotective effect of garlic. Our findings go parallel with previous reports [33, 58]. Razo-Rodriguez et al. assured that garlic extract can maintain the levels of serum urea and creatinine through its organo-sulfur compounds [65]. Moreover, these compounds could enhance the antioxidant effect and inhibit lipid peroxide levels by scavenging the free radicals and increasing intracellular concentration of glutathione.
The present study revealed a significant decrease in the serum sodium and potassium in CP-treated mother rats and their offspring. Such results came in agreement with the findings of previous studies [66, 67] which showed excess elimination of potassium and sodium in patients treated with CP. An early study by Daugaard et al. confirmed that, CP metabolites can inhibit the mechanism involving in electrolytes reabsorption especially in the distal segment of the nephron, resulting in hypokalemia and hyponatremia [68]. Furthermore, CP can induce disturbance in both intestinal absorption and renal tubular reabsorption of potassium [66]. Another study clarified that CPcan inhibit the activity of antidiurtic hormone (ADH) leading to hypernatremia [69].
Garlic was known to have various active antioxidant organo-sulfur compounds mainly S-Allylcysteine and allicin [70,71] These compounds can enhance the cellular antioxidant enzymes, increased GPx content in the cells and scavenged the free radicals [59, 71] The ameliorative effects of garlic against doxorubicin induced cardiotoxicity [72], cadmium-induced toxicity [52] and acrylamide-induced oxidative stress in various organs [73] have been previously documented in researches. In the current study, treatment of mother rats with garlic extract alone or in combination with CP produced significant decline in MDA level and significant increase of SOD, CAT and GPx activities in the renal tissues. These findings support the antioxidant effects of garlic extract against CP-induced oxidative damage and lipid peroxidation. Lanzotti revealed that the thiosulfinates compounds of garlic play a major role in enhancing the antioxidants enzymes [74]. Capasso added that the protective effect of garlic is mainly mediated by its highly bioavailable and significant antioxidant compounds especially S-allyl cysteine, S-allyl mercaptocyteine, allicin, and selenium that exhibited potent antioxidant activity [59]. Moreover, the water-soluble S-allyl cysteine reduced the extent of lipid peroxidation and obviously stimulated antioxidant activities in vitro and in vivo [75]. In agreement with present study, significant increase in CAT, SOD and GPx activities accompanied with significant decline in MDA was recorded in animals treated with garlic [76,77]. The obtained results in the present work concerning the reduction in the activity of renal antioxidant enzymes; CAT, SOD and GPx and elevated lipid peroxidation (MDA) in CP treated mother rats are in accordance with the findings of previous studies [65,78]. Sheikh-Hamad et al. declared that CP can liberate NO that implicated in oxidative stress and nephrotoxicity [79]. Kart et al. added that CP is implicated in in generation of ROS that induce disturbance in membrane permeability and severe cell damage [80]. Elevation of the MDA enhanced lipid peroxidation and increased ROS generation leading to disturbance of membrane function and integrity [81]. Furthermore, inhibition of antioxidant CAT, SOD, and GPx enzymes was implicated in the pathogenesis of CP-induced nephrotoxicity.
Caspases are a family of proteases that play an important role in the regulation of apoptosis [82]. In the current investigation, caspase-3 (strong apoptotic marker) has been shown to be increased in the renal tissues of CP-treated mother's rats and their offsprings. The obtained result is in accordance with the previous studies [82, 83]. Sheikh-Hamad et al. reported that, CP can induce apoptosis through activation of tumor necrosis factor (TNF) or messages form caspases 1, 2, 3 and 8 that activate caspase-3 in kidney [79]. Razzaque et al. revealed that CP increased expression of both Fas and Fas ligand in human proximal tubular epithelial cells which accelearate tha activity of caspse-3[84]. Other researchers reported that, CP can induce apoptosis in the renal tubular epithelial cells resulting in activation of caspase-9, which is a good promoter for the mitochondrial apoptotic pathway [83,85]. Further studies explained that CP can induce apoptosis with progressive accumulation of DNA and inhibition of DNA repair pathways, through generation of reactive oxygen species [57, 86].
Garlic was found to attenuate the increased caspase-3 levels induced by CP treatment. Previously, it was reported that, protein s-allyl cysteine (SAC) is the most abundant compound in the garlic extract that prevents the lipid peroxidation (LPO) by ROS, the oxidative damage to DNA and apoptosis [33, 87].
In conclusion, in light of the demonstrated findings in this investigation, protective imprints of garlic extract against most of CP-induced histological and biochemical changes were found. Garlic extract has powerful ameliorative effects on CP-induced oxidative stress and renal damage through its antioxidant, anti-inflammatory and antiapoptotic properties through post-treatment with garlic extract. Eventually, further studies with different dose regimens and on larger number of animals over longer durations are recommended.