الفهرس 
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Abstract
The present study aimed to clarify the possible protective effect of L-arginine against adrenal cortex toxicity induced by Aspartame.
This study was carried out on 50 adult male albino rats divided randomly into five groups as follows:
group I (10 rats): served as control and were given only distilled water for 4 weeks.
group II (10 rats) (L-arginine-treated group) (LA): each rat received 0.3mg/ gm/day dissolved in distilled water and given by gastric gavage for 4 weeks (Mahar et al., 2021).
group III (10 rats) (Aspartame-treated group) (AS): each rat received 250mg/Kg/day dissolved in distilled water and given by gastric gavage for 4 weeks (Abdelhaliem and Mohamed, 2017).
group IV (10 rats) (LA+AS group): each rat was given L-arginine at the same dose, period, and route of administration of the group II concomitantly with Aspartame at the same dose and route of group III for 4 weeks (Abdelhaliem and Mohamed, 2017; Mahar et al., 2021).
group V (10 rats) (Recovery group): each rat received aspartame as in group IV. Then, rats were left for four weeks after stopping aspartame administration to recover before they were sacrificed (Bekheet and Rady, 2020).
I) Histological results:
1-Hematoxylin and Eosin:
Histological observations of group I (control group) and group II (L-arginine group), showed normal histoarchitecture of the adrenal gland. It was formed of a connective tissue capsule, surrounding the parenchyma which included two main parts: cortex and medulla. The adrenal cortex was formed of three zones from outside inwards: zona glomerulosa (ZG), zona fasciculata (ZF) and zona reticularis (ZR), while the histological examination showed extensive damage to the adrenal cortex in group III (Aspartame group), with disintegration of the capsule and disorganization of the arrangement of the cells of the adrenal cortex. group IV (Aspartame and L-Arginine-treated group) displayed apparent improvement in the structure of the adrenal cortex as compared to rats receiving aspartame in group III. The adrenal cortex exhibited normal architecture with well demarcation between the cortical zones; ZG, ZF and ZR. The capsule appeared restored and uniform in all parts of the adrenal gland. Regarding group V (recovery group), histological examination revealed persistence of some apparent adrenal cortical structural changes that occurred in aspartame-group after stoppage of aspartame administration for 4 weeks. These results demonstrated that L-Arginine exerted cytoprotective effects against adrenal cortex toxicity induced by Aspartame.
2-Masson’s trichome:
The adrenal cortex sections in rats administrated with aspartame (group III) displayed distortion & separation of the capsule with apparent decrease in its thickness with irregular thin bluish-green trabeculae extending between the cells of ZG when compared to the rats in control group (group I), indicating the destructive effect of aspartame in the collagen fibers of adrenal gland capsule and trabeculae.
3-Periodic-acid Schiff:
PAS-stained sections from adrenal cortex of rats in group III (Aspartame group) demonstrated disturbed, unclear cell membranes especially among cells of ZG and ZF with restoration of well-defined intact cell membranes in rats of group IV (L-Arginine and Aspartame-treated group).
4-Immunohistochemical results:
Caspase 3:
Expression of Caspase-3 as an apoptotic marker using immunohistochemical staining was used to determine the degree of apoptosis in the adrenal cortex. the degree of brown staining reflects the level of Caspase-3 expression and hence, the apoptotic status in the tissue. There is an obvious increase in nuclear and cytoplasmic brown staining in the aspartame-exposed group (III), compared to the control group (I) indicating an increase in Caspase-3 expression.
VEGF:
VEGF is a potent angiogenic factor and a mitogen for vascular endothelium. The expression of VEGF in the adrenal cortex was upregulated in the aspartame group (III) but downregulated in L-arginine and aspartame treated group (IV) and that confirmed the angiogenic effect of aspartame.
II) Biochemical results
1-Mean serum ACTH, Aldosterone, and Cortisol levels:
group III (Aspartame group) recorded a significant increase (P<0.05) in the mean serum aldosterone, cortisol and ACTH levels as compared with group I (Control), group II (L-Arginine), group IV (Aspartame and L-Arginine), and group V (Recovery). However, group IV (Aspartame and L-Arginine) showed significant decrease (P<0.05) in mean serum aldosterone, cortisol and ACTH levels as compared with group III (Aspartame) and group V (Recovery) and significant increase (P<0.05) as compared with group I (Control) and group II (L-Arginine).
2-Mean serum Malondialdehyde (MDA):
group III (aspartame group) showed a significant increase (P<0.05) in the mean serum MDA (Malondialdehyde) level as compared with group I (Control), group II (L-Arginine), group IV (aspartame and L-Arginine), and group V (recovery). However, group IV (aspartame and L-arginine) showed significant decrease (P<0.05) in mean serum MDA (Malondialdehyde) level as compared with group III (Aspartame) and group V (Recovery) and significant increase (P<0.05) as compared with group I (Control) and group II (L-Arginine).
3-Mean serum Reduced Glutathione (GSH):
group III (aspartame group) showed a significant decrease (P<0.05) in the mean serum GSH (Reduced Glutathione) level as compared with group I (Control), group II (L-Arginine), group IV (Aspartame and L-Arginine), and group V (recovery). On the other hand, group IV (aspartame and L-arginine) showed significant increase (P<0.05) in mean serum GSH (Reduced Glutathione) level as compared with group III (Aspartame) and group V (Recovery) and significant decrease (P<0.05) as compared with group I (Control) and group II (L-Arginine).
III) Morphometric analysis
Done using Leica image analyzer to measure the mean thickness of ZF, The mean area percentage of Collagen fibres content in Masson’sTrichome-stained sections, and the mean area percentage of capase-3 and VEGF positive reactions.
IV) Statistical analysis
Performed using one way ANOVA to compare between the different groups, P < 0.05 was considered significant.