Histomorphological, Histochemical and Ultrastructural Studies on the Healthy Liver of Yemen Veiled Chameleon (Chamaeleo calyptratus) in Southern Saudi Arabia / Estudios Histomorfológicos, Histoquímicos y Ultraestructurales en el Hígado Sano del Camaleón Velado de Yemen (Chamaeleo calyptratus) en el Sur de Arabia Saudita

SUMMARY: The livers of reptiles are being studied as a model for the link between the environment and hepatic tissue. There have been few investigations on the histology of reptile livers, and very few or no studies have examined the histology of liver of veiled chameleon (Chamaeleo calyptratus). This paper describes the histomorphological, histochemical and ultrastructural characterization of the liver of veiled chameleons in southern Saudi Arabia. Seven Chamaeleo calyptratus were captured in the summer season in Abha City, Aseer region, southern Saudi Arabia. Chamaeleon liver samples were processed for histomorphology, histochemistry and ultrastructure analyses. Morphologically liver of Chamaeleo calyptratus was observed as a large dark brown organ with lighter speckles, which represent melanin deposits. It located at the ventral part of abdominal cavity forward of the stomach. Its dimensions approximately were 3.7 x 2 cm. The liver was a bilobed organ divided into two lobes, right and left lobes. The right one was bigger than the others. The gallbladder was well developed and had an elongated shape, situated between the two lobes and contained the bile for the digestion. Microscopically, the liver was found to be covered by a thick layer of connective tissue, which formed the hepatic capsule. Hepatic parenchyma probably appeared in cross sections as hepatic glandular-like alveoli "acini" or follicular structures with various diameters, each acinus contains approximately four to six hepatocytes, surrounded by sinusoidal capillaries filled with abundant melanomacrophages, which are absent in birds and mammals. Melanomacrophages are common in the hepatic parenchyma's perisinusoidal areas, particularly near portal spaces. Hepatocytes are polyhedral or pyramidal with and mostly contained large, rounded nuclei mostly peripherally located, with prominent dark oval nucleoli. Some of nuclei are eccentric or central position. The cytoplasm appeared spongy or vacuolated and more eosinophilic when stained by hematoxylin-eosin and strongly reactive to PAS staining technique, indicating abundant glycogen content. The reticular fibers that surround hepatocytes, blood arteries, and sinusoids supported the hepatic parenchyma. The blood sinusoids are seen interspersed among hepatocytes of varying sizes. The sinusoidal lumen was bordered by flattened endothelial cells and includes elliptical nucleated erythrocytes and liver macrophages as phagocytes, which are also known as Kupffer cells. Branches of the portal vein, hepatic artery, small bile duct, and lymph vessels were detected in the hepatic portal area "tract" or triad which made up of connective. Hematopoietic tissue was observed in subcapsular region and portal triads. Ultrastructurally, the hepatocyte appeared polyhedric containing a single large rounded basal or eccentric vesicular nucleus with prominent nucleolus. Extensive network of rough endoplasmic reticulum (RER) often arranged in an array parallel to the nuclear membrane with many mitochondria, and Golgi apparatus were described. The cytoplasm contained glycogen granules, vesicles or vacuoles scattered throughout the cytoplasm especially at the apical region were reported. The bile canaliculi and the hepatic "Kupffer" cells were also discussed. This is the first study on the histological characterization of the healthy liver of Yemen veiled chameleon in southern Saudi Arabia. The findings reported here should be used as a reference to compare with the pathological abnormalities of the liver in this animal.

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Sub-chronic administration of vincristine sulfate induces renal damage and apoptosis in rats via induction of oxidative stress and activation of Raf1-MEK1/2-Erk1/2 signal transduction / La administración subcrónica de sulfato de vincristina induce daño renal y apoptosis en ratas por inducción de estrés oxidativo y activación de la transducción de señales Raf1-MEK1/2-Erk1/2

SUMMARY: In spite of being one of the most powerful anti-cancer drug, the nephrotoxicity of Vincristine (VCR) is not well established in either animals or humans. Hence, this study evaluates the nephrotoxic effect of VCR in rats after sub-chronic long-term administration. Rats were divided into 2 groups (n=10/group) of either control and VCR treated rats (50 mg/kg). Treatments were carried out for 30 consecutive days, after which a series of biochemical and molecular experiments related to kidney function were evaluated. VCR administration significantly decreased the survival rate (69.8 %) and impaired renal function as evidenced by lowered creatinine (Cr) clearance (Ccr), high serum levels of urea and Cr, increased urinary protein levels and resulted in sever cortex pathological alterations, including glomerulus congestion and damage as well as vascular degenerations up to necrosis of both proximal and distal convoluted tubules. Mechanistically, VCR lowered renal antioxidant potential and ATP levels, enhanced lipid peroxidation and induced inflammation. In addition, VCR induced activation of Raf-1-MEK1/2-ERK1/2 signaling pathway leading to downregulation of Bcl2 and upregulation of P53, Bax, and cleaved caspase-3. In conclusion, these findings show a nephrotoxic effect of VCR sulfate in rats after sub-chronic administration and such effect was mediated by activation of ERK1/2 induced apoptosis.

RESUMEN: A pesar de ser uno de los medicamentos de mayor eficacia contra el cáncer, aún no se ha establecido la nefrotoxicidad de la vincristina (VCR) en animales y humanos. Por lo tanto, este estudio evalúa el efecto nefrotóxico de la VCR en ratas después de la administración subcrónica a largo plazo. Las ratas se dividieron en 2 grupos (n = 10 / grupo) de control y ratas tratadas con VCR (50 mg / kg). Los tratamientos se llevaron a cabo durante 30 días consecutivos, después de los cuales se evaluaron una serie de experimentos bioquímicos y moleculares relacionados con la función renal. La administración de VCR disminuyó significativamente la tasa de supervivencia (69,8 %), dificultó la función renal, lo que se observó además en los bajos niveles de creatinina (Cr) (Ccr), los niveles séricos elevados de urea y Cr, un nivel más alto de proteína urinaria, los que dieron lugar a alteraciones patológicas severas de la corteza, incluido el glomérulo congestión y daño, como también degeneraciones vasculares, incluyendo la necrosis de los túbulos contorneados proximales y distales. Mecánicamente, el VCR redujo el potencial antioxidante renal y los niveles de ATP, mejoró la peroxidación lipídica y la inflamación inducida. Además, la VCR indujo la activación de la vía de señalización Raf-1-MEK1 / 2-ERK1 / 2 que conduce a la regulación negativa de Bcl-2 y la regulación positiva de P53, Bax y la caspasa-3. En conclusión, estos hallazgos muestran un efecto nefrotóxico del sulfato de VCR en ratas después de la administración subcrónica. Dicho efecto fue mediado por la activación de la apoptosis inducida por ERK1 / 2.