Behavioural and histopathological analyses of ibuprofen treatment on the effect of aggregated AB (1-42) injections in the rat

It has been suggested that inflammatory processes may play a role in the development of Alzheimerâ??s disease (AD), and that nonsteroidal anti-inflammatory drug treatments may provide protection against the onset of AD. In the current study male Wistar rats were trained in two-lever operant chambers under an alternating lever cyclic-ratio ratio (ALCR) schedule. When responding showed no trends, subjects were divided into groups. One group was bilaterally injected into the CA3 area of the hippocampus with 5 μl of aggregated β-amyloid (Aβ) suspension, and one group was bilaterally injected into the CA3 area of the hippocampus with 5 μl of sterile saline. Subgroups were treated twice daily with 0.1 ml (40 mg/kg) ibuprofen administered orally. The results indicated that chronic administration of ibuprofen protected against detrimental behavioural effects following aggregated Aβ injections. Withdrawal of ibuprofen treatment from aggregated Aβ-injected subjects produced a decline in behavioural performance to the level of the non-treated aggregated Aβ-injected group. Ibuprofen treatment reduced the numbers of reactive astrocytes following aggregated Aβ injection, and withdrawal of ibuprofen resulted in an increase of reactive astrocytes. These results suggest that induced inflammatory processes may play a role in AD, and that ibuprofen treatment may protect against some of the symptoms seen in AD.

Effects of intrahippocampal NAC(61-95) injections on memory in the rat and attenuation with vitamin E

Parkinson's disease (PD)-related dementia affects approximately 40% of PD patients and the severity of this dementia correlates significantly with the density of Lewy body (LB) deposition in the PD brain. Aggregated alpha-synuclein protein is the major component of LB's and the non-amyloid component (NAC) region of alpha-synuclein, residues 61-95, is essential for the aggregation and toxicity of this protein. The current study evaluated the effect of pre-aggregated NAC(61-95) injected into the CA3 area of the dorsal hippocampus of the brain on memory in the rat. Previous research has suggested that oxidative stress processes may play a role in the neuropathology of PD, therefore the effect of treatment with vitamin E, an antioxidant, was also evaluated. Male Sprague-Dawley rats were trained in two-lever operant chambers under an alternating-lever cyclic-ratio (ALCR) schedule of food reinforcement. When responding showed no trends, subjects were divided into four groups. Two groups were injected bilaterally into the dorsal hippocampus with aggregated NAC(61-95) (5 mu l suspension), and two groups were injected bilaterally into the dorsal hippocampus with sterile water (5 mu l). Subgroups were treated with either vitamin E (150 mg/kg in Soya oil) or vehicle (Soya oil) daily. Injection of NAC(61-95) induced memory deficits and vitamin E treatment alleviated these. In addition, NAC(61-95) injections induced activated astrocytes and chronic treatment with vitamin E reduced the numbers of activated astrocytes. These results suggest that aggregated NAC(61-95) and associated oxidative stress, may play a role in the pathogenesis of cognitive deficits seen in PD-induced dementia. (C) 2009 Elsevier Inc. All rights reserved.

AßPP over-expressing transgenic rat model of Alzheimer's disease utilizing the Tg2576 mouse protocol.

The current study examined behavioral and histological effects of amyloid-ß (Aß) protein precursor (AßPP) overexpression in transgenic (Tg) rats created using the same gene, mutation, and promoter as the Tg2576 mouse model of Alzheimer's disease (AD). Male Tg+ rats were bred with female wild-type rats to generate litters of hemizygous Tg+ and Tg- offspring. Tg+ rats and Tg- littermates were tested for memory deficits at 4, 8, and 12 months old using a water-maze procedure. There were no significant behavioral differences between Tg+ rats and Tg- littermates at 4 months old but there were significant differences at 8 and 12 months old, and in probe trials at 8 and 12 months old, the Tg+ rats spent significantly less time and covered less distance in the platform zone. Under acquisition of a fixed-consecutive number schedule at 3 months old, Tg- littermates demonstrated a longer latency to learning the response rule than Tg+ rats; while this might seem paradoxical, it is consistent with the role of overexpression of AßPP in learning. Histological analyses revealed activated astrocytes in brains of Tg+ rats but not Tg- littermates at 6 months old, and thioflavin-S positive staining in the hippocampus and cortex of 17-month old Tg+ rats but not Tg- littermates. Quantification of Aß load in the brain at 22 months indicated high levels of Aß38, Aß40, and Aß42 in the Tg+ rats. These data suggest this model might provide a valuable resource for AD research.

Fractionated Radiation Exposure of Rat Spinal Cords Leads to Latent Neuro- Inflammation in Brain, Cognitive Deficits,and Alterations in Apurinic Endonuclease 1

Ionizing radiation causes degeneration of myelin, the insulating sheaths of neuronal axons, leading to neurological impairment. As radiation research on the central nervous system has predominantly focused on neurons, with few studies addressing the role of glial cells, we have focused our present research on identifying the latent effects of single/ fractionated -low dose of low/ high energy radiation on the role of base excision repair protein Apurinic Endonuclease-1, in the rat spinal cords oligodendrocyte progenitor cells’ differentiation. Apurinic endonuclease-1 is predominantly upregulated in response to oxidative stress by low- energy radiation, and previous studies show significant induction of Apurinic Endonuclease-1 in neurons and astrocytes. Our studies show for the first time, that fractionation of protons cause latent damage to spinal cord architecture while fractionation of HZE (28Si) induce increase in APE1 with single dose, which then decreased with fractionation. The oligodendrocyte progenitor cells differentiation was skewed with increase in immature oligodendrocytes and astrocytes, which likely cause the observed decrease in white matter, increased neuro-inflammation, together leading to the observed significant cognitive defects.

Quantification of urinary excretion of ethosuximide enantiomers and their major metabolites in the rat.

A chiral gas chromatographic assay has been developed for quantitative analysis of ethosuximide and its major metabolites in rat urine. The extraction procedure was found to be precise and reproducible. Recovery was in the range of 94-98%, intraday CV(%) was 0.92% for (S)-ethosuximide (50 mug/ml) and 0.51% for (R)-ethosuximide (50 mug/ml). Interday CV(%) was 1.12% for (S)-ethosuximide and 0.72% for (R)-ethosuximide. The limit of detection was determined to be around 0.01 mug/ml for each enantiomer. Following administration of rac-ethosuximide by i.v., i.p. and oral routes, unchanged ethosuximide was detected in urine up to 72h after drug administration. The appearance of all detected metabolites occurred Within 24h of drug administration. Significantly more (S)-ethosuximide was excreted unchanged than (R)-ethosuximide with all three routes studied. A substantial amount of the drug was eliminated as the 2-(1-hydroxyethyl)-2-methylsuccinimide (2 pairs of diastereoisomers). Much less drug was eliminated as the 2-ethyl-3-hydroxy-2-methylsuccinimide with only one diastereoisomer observed. Examination of the one pair of diastereoisomers of 2-(1-hydroxyethyl)-2-methylsuccinimide that was resolved showed preferential excretion of one isomer. Comparison of both pairs of diastereoisomers showed that one pair was formed in preference to the other with a ratio of approximately 0.8:1. It is concluded that stereoselective metabolism of ethosuximide occurs. Copyright (C) 2001 John Wiley & Sons, Ltd. Author Keywords: chiral pharmacokinetics; ethosuximide enantiomers; metabolism; rat; urinary excretion; gas chromatography

Changes in fos expression in the rat brain after unilateral lesions of the anterior thalamic nuclei

Activity of the immediate early gene c-fos was compared across hemispheres in rats with unilateral anterior thalamic lesions. Fos protein was quantified after rats performed a spatial working memory test in the radial-arm maze, a task that is sensitive to bilateral lesions of the anterior thalamic nuclei. Unilateral anterior thalamic lesions produced evidence of a widespread hippocampal hypoactivity, as there were significant reductions in Fos counts in a range of regions within the ipsilateral hippocampal formation (rostral CA1, rostral dentate gyrus, 'dorsal' hippocampus, presubiculum and postsubiculum). A decrease in Fos levels was also found in the rostral and caudal retrosplenial cortex but not in the parahippocampal cortices or anterior cingulate cortices. The Fos changes seem most closely linked to sites that are also required for successful task performance, supporting the notion that the anterior thalamus, retrosplenial cortex and hippocampus form key components of an interdependent neuronal network involved in spatial mnemonic processing.

Carbachol triggers RyR-dependent Ca(2+) release via activation of IP(3) receptors in isolated rat gastric myocytes.

Possible interactions between different intracellular Ca(2+) release channels were studied in isolated rat gastric myocytes using agonist-evoked Ca(2+) signals. Spontaneous, local Ca(2+) transients were observed in fluo-4-loaded cells with linescan confocal imaging. These were blocked by ryanodine (100 microM) but not by the inositol 1,4,5-trisphosphate receptor (IP(3)R) blocker, 2-aminoethoxydiphenyl borate (100 microM), identifying them as Ca(2+) sparks. Caffeine (10 mM) and carbachol (10 microM) initiated Ca(2+) release at sites which co-localized with each other and with any Ca(2+) spark sites. In fura-2-loaded cells extracellular 2-aminoethoxydiphenyl borate and intracellular heparin (5 mg ml(-1)) both inhibited the global cytoplasmic [Ca(2+)] transient evoked by carbachol, confirming that it was IP(3)R-dependent. 2-Aminoethoxydiphenyl borate and heparin also increased the response to caffeine. This probably reflected an increased Ca(2+) store content since 2-aminoethoxydiphenyl borate more than doubled the amplitude of transients evoked by ionomycin. Ryanodine completely abolished carbachol and caffeine responses but only reduced ionomycin transients by 30 %, suggesting that blockade of carbachol transients by ryanodine was not simply due to store depletion. Double labelling of IP(3)Rs and RyRs demonstrated extensive overlap in their distribution. These results suggest that carbachol stimulates Ca(2+) release through co-operation between IP(3)Rs and RyRs, and implicate IP(3)Rs in the regulation of Ca(2+) store content.