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Irradiated Rats (irradiated + rat)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

SALIVATION TRIGGERED BY PILOCARPINE INVOLVES AQUAPORIN-5 IN NORMAL RATS BUT NOT IN IRRADIATED RATS

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2009
Tetsuya Asari
SUMMARY 1Using rats, we examined the muscarinic receptor subtype mediating pilocarpine-induced parotid salivary secretion and the contributions of ion transporter systems (effluxes of K+ and Cl - ) and aquaporin-5 (AQP5) translocation to this response in parotid glands in irradiated-induced xerostomia. 2Salivary secretion was significantly lower in irradiated compared with sham-irradiated (normal) rats. In xerostomia rats, 0.4 and 0.8 mg/kg pilocarpine significantly increased parotid salivary secretion, although the salivary volume was still significantly less than in normal rats after the same dose of pilocarpine. 3Pirenzepine (1 × 10,6 to 1 × 10,1 mol/L), AF-DX 116 (3 × 10,6 to 3 × 10,2 mol/L) and N -2-chloroethyl-4-piperidinyl diphenylacetate (4-DAMP; 1 × 10,8 to 1 × 10,2 mol/L) dose-dependently displaced radioligand binding to M1, M2 and M3 receptors, respectively, in parotid membranes from both normal and irradiated rats. In each group of rats, 4-DAMP had the highest binding affinity. Pretreatment with 4-DAMP or pirenzepine dose-dependently inhibited pilocarpine-induced parotid secretion in both normal and irradiated rats, with 4-DAMP being markedly more potent than pirenzepine. 4Normal and irradiated-rat parotid cells did not differ significantly in terms of pilocarpine-induced changes in [Ca2+]i, [K+]i and [Cl - ]i. Pilocarpine markedly increased the amount of AQP5 in the apical plasma membrane of parotid cells isolated from normal but not irradiated rats. 5Thus, pilocarpine induces parotid salivary secretion mainly via the M3 receptor subtype in both irradiated and normal rats. The reduction in this pilocarpine-induced secretion seen in irradiated rats is due not to disturbances of intracellular Ca2+ mobilization or ion transporter systems, but rather to a disturbance of AQP5 translocation, which may be involved in the pathogenesis of X-ray irradiation-induced xerostomia. [source]

Electroencephalographic Characterization of an Adult Rat Model of Radiation-Induced Cortical Dysplasia

EPILEPSIA, Issue 10 2001
Shinji Kondo
Summary: ,Purpose: Cortical dysplasia (CD) is a frequent cause of medically intractable focal epilepsy. The mechanisms of CD-induced epileptogenicity remain unknown. The difficulty in obtaining and testing human tissue warrants the identification and characterization of animal model(s) of CD that share most of the clinical, electroencephalographic (EEG), and histopathologic characteristics of human CD. In this study, we report on the in vivo EEG characterization of the radiation-induced model of CD. Methods: Timed-pregnant Sprague,Dawley rats were irradiated on E17 using a single dose of 145 cGy or left untreated. Their litters were identified and implanted with bifrontal epidural and hippocampal depth electrodes for prolonged continuous EEG recordings. After prolonged EEG monitoring, animals were killed and their brains sectioned and stained for histologic studies. Results: In utero,irradiated rats showed frequent spontaneous interictal epileptiform spikes and spontaneous seizures arising independently from the hippocampal or the frontal neocortical structures. No epileptiform or seizure activities were recorded from age-matched control rats. Histologic studies showed the presence of multiple cortical areas of neuronal clustering and disorganization. Moreover, pyramidal cell dispersion was seen in the CA1>CA3 areas of the hippocampal formations. Conclusions: Our results further characterize the in vivo EEG characteristics of the in utero radiation model of CD using long-term EEG monitoring. This model may be used to study the molecular and cellular changes in epileptogenic CD and to test the efficacy of newer antiepileptic medications. [source]

Role of heat shock protein 47 on tubulointerstitium in experimental radiation nephropathy

PATHOLOGY INTERNATIONAL, Issue 5-6 2002
Diange Liu
The molecular mechanisms of fibrosis in radiation nephropathy have received scant attention. Heat shock protein 47 (HSP47), a collagen-binding stress protein, helps in the intracellular processing of procollagen molecules during collagen synthesis. We investigated the role of HSP47 in the progression of radiation nephropathy using experimental radiation nephropathy. Experimental rat groups were as follows: (i) group I, sham operated (n = 12); (ii) group II, single doses of irradiation, either 7, 15 or 25 Gy to left kidney (n = 60); and (iii) group III, a similar irradiation procedure as group II after right nephrectomy (n = 60). The rats were followed up until 9 months after renal exposure to radiation. Renal dysfunction (as determined by serum creatinine and blood urea nitrogen) and hypertension were noted in group III rats, along with inflammatory cell infiltration and interstitial fibrosis (as determined by increased deposition of collagens). Compared to control rat kidneys, an increased expression of HSP47 was noted in kidneys obtained from irradiated rats. By double immunostaining, HSP47-expressing cells were identified as ,-smooth muscle actin-positive myofibroblasts and vimentin-positive tubular epithelial cells. Increased expression of HSP47 was closely associated with increased deposition of collagens in the widened interstitium of irradiated rats. Overexpression of HSP47 by phenotypically altered tubulointerstitial cells might play a role in excessive assembly/synthesis of collagens and could contribute to tubulointerstitial fibrosis in radiation nephropathy. [source]

In Vivo Radioprotective Effects of Nigella sativa L Oil and Reduced Glutathione Against Irradiation-Induced Oxidative Injury and Number of Peripheral Blood Lymphocytes in Rats

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2006
Mustafa Cemek
Radiotherapy is one of the most common therapies for treating human cancers. Several studies have indicated that irradiation induces reactive oxygen species (ROS), which play an important role in radiation damage of the cell. It has been shown that Nigella saliva L. (NS) and reduced glutathione (GSH) have both an antiperoxidative effect on different tissues and a scavenger effect on ROS. The purpose of this study was to determine the antioxidant and radio-protective roles of NS and GSH against irradiation-induced oxidative injury in an experimental model. The NS group was administrated NS (1 mL/kg body weight), the GSH group was injected GSH (150 mg/kg body weight) and the control group was given physiologic saline solution (1 mL/kg body weight) for 30 consecutive days before exposure to a single dose of 6 Gy of radiation. Animals were sacrificed after irradiation. Malondialdehyde, nitrate, nitrite (oxidative stress markers) and ascorbic acid, retinol, ,-carotene, GSH and ceruloplasmin (nonenzymatic antioxidant markers) levels and peripheral blood lymphocytes were measured in all groups. There were statistically significant differences between the groups for all parameters (P < 0.05). Whole-body irradiation caused a significant increase in blood malondialdehyde, nitrate and nitrite levels. The blood oxidative stress marker levels in irradiated rats that were pretreated with NS and GSH were significantly decreased; however, non-enzymatic antioxidant levels were significantly increased. Also, our results suggest that NS and GSH administration prior to irradiation prevent the number of alpha-naphthyl acetate esterase peripheral blood T lymphocytes from declining. These results clearly show that NS and GSH treatment significantly antagonize the effects of radiation. Therefore, NS and GSH may be a beneficial agent in protection against ionizing radiation-related tissue injury. [source]