The presymptomatic treatment with 3HFWC nanosubstance decreased plaque load in 5XFAD mouse model of Alzheimer's disease

INTRODUCTION

In the present study, we assessed the effects of the hyper-harmonized-hydroxylated fullerene-water complex (3HFWC) on Alzheimer's disease (AD) neuropathological hallmarks in 5XFAD mice, an AD animal model.

METHODS

The 3-week-old 5XFAD mice were exposed to 3HFWC water solution ad libitum for 3 months in the presymptomatic phase of pathology. The functional effects of the treatment were confirmed through near-infrared spectroscopy (NIRS) analysis through machine learning (ML) using artificial neural networks (ANNs) to classify the control and 3HFWC-treated brain tissue samples. The effects of 3HFWC treatment on amyloid-β (Aβ) accumulation, plaque formation, gliosis, and synaptic plasticity in cortical and hippocampal tissue were assessed.

RESULTS

The 3HFWC treatment significantly decreased the amyloid-β plaque load in specific parts of the cerebral cortex. At the same time, 3HFWC treatment did not induce the activation of glia (astrocytes and microglia) nor did it negatively affect synaptic protein markers (GAP-43, synaptophysin, and PSD-95).

CONCLUSION

The obtained results point to the potential of 3HFWC, when applied in the presymptomatic phase of AD, to interfere with amyloid plaque formation without inducing AD-related pathological processes such as neuroinflammation, gliosis, and synaptic vulnerability.

The supplementation of a high dose of fish oil during pregnancy and lactation led to an elevation in Mfsd2a expression without any changes in docosahexaenoic acid levels in the retina of healthy 2-month-old mouse offspring

Introduction

During fetal development, the proper development of neural and visual systems relies on the maternal supplementation of omega-3 fatty acids through placental transfer. Pregnant women are strongly advised to augment their diet with additional sources of omega-3, such as fish oil (FO). This supplementation has been linked to a reduced risk of preterm birth, pre-eclampsia, and perinatal depression. Recently, higher doses of omega-3 supplementation have been recommended for pregnant women. Considering that omega-3 fatty acids, particularly docosahexaenoic acid (DHA), play a crucial role in maintaining the delicate homeostasis required for the proper functioning of the retina and photoreceptors the effects of high-dose fish oil (FO) supplementation during pregnancy and lactation on the retina and retinal pigmented epithelium (RPE) in healthy offspring warrant better understanding.

Methods

The fatty acid content and the changes in the expression of the genes regulating cholesterol homeostasis and DHA transport in the retina and RPE were evaluated following the high-dose FO supplementation.

Results

Our study demonstrated that despite the high-dose FO treatment during pregnancy and lactation, the rigorous DHA homeostasis in the retina and RPE of the two-month-old offspring remained balanced. Another significant finding of this study is the increase in the expression levels of major facilitator superfamily domain-containing protein (Mfsd2a), a primary DHA transporter. Mfsd2a also serves as a major regulator of transcytosis during development, and a reduction in Mfsd2a levels poses a major risk for the development of leaky blood vessels.

Conclusion

Impairment of the blood-retinal barrier (BRB) is associated with the development of numerous ocular diseases, and a better understanding of how to manipulate transcytosis in the BRB during development can enhance drug delivery through the BRB or contribute to the repair of central nervous system (CNS) barriers.

Dietary restriction alters insulin signaling pathway in the brain

Insulin is known to be a key hormone in the regulation of peripheral glucose homeostasis, but beyond that, its effects on the brain are now undisputed. Impairments in insulin signaling in the brain, including changes in insulin levels, are thought to contribute significantly to declines in cognitive performance, especially during aging. As one of the most widely studied experimental interventions, dietary restriction (DR) is considered to delay the neurodegenerative processes associated with aging. Recently, however, data began to suggest that the onset and duration of a restrictive diet play a critical role in the putative beneficial outcome. Because the effects of DR on insulin signaling in the brain have been poorly studied, we decided to examine the effects of DR that differed in onset and duration: long-term DR (LTDR), medium-term DR (MTDR), and short-term DR (STDR) on the expression of proteins involved in insulin signaling in the hippocampus of 18- and 24-month-old male Wistar rats. We found that DR-induced changes in insulin levels in the brain may be independent of what happens in the periphery after restricted feeding. Significantly changed insulin content in the hippocampus, together with altered insulin signaling were found under the influence of DR, but the outcome was highly dependent on the onset and duration of DR.

The Expression of Major Facilitator Superfamily Domain-Containing Protein2a (Mfsd2a) and Aquaporin 4 Is Altered in the Retinas of a 5xFAD Mouse Model of Alzheimer's Disease

Cerebral amyloid angiopathy (CAA) is characterized by amyloid β (Aβ) accumulation in the blood vessels and is associated with cognitive impairment in Alzheimer's disease (AD). The increased accumulation of Aβ is also present in the retinal blood vessels and a significant correlation between retinal and brain amyloid deposition was demonstrated in living patients and animal AD models. The Aβ accumulation in the retinal blood vessels can be the result of impaired transcytosis and/or the dysfunctional ocular glymphatic system in AD and during aging. We analyzed the changes in the mRNA and protein expression of major facilitator superfamily domain-containing protein2a (Mfsd2a), the major regulator of transcytosis, and of Aquaporin4 (Aqp4), the key player implicated in the functioning of the glymphatic system, in the retinas of 4- and 12-month-old WT and 5xFAD female mice. A strong decrease in the Mfsd2a mRNA and protein expression was observed in the 4 M and 12 M 5xFAD and 12 M WT retinas. The increase in the expression of srebp1-c could be at least partially responsible for the Mfsd2a decrease in the 4 M 5xFAD retinas. The decrease in the pericyte (CD13+) coverage of retinal blood vessels in the 4 M and 12 M 5xFAD retinas and in the 12 M WT retinas suggests that pericyte loss could be associated with the Mfsd2a downregulation in these experimental groups. The observed increase in Aqp4 expression in 4 M and 12 M 5xFAD and 12 M WT retinas accompanied by the decreased perivascular Aqp4 expression is indicative of the impaired glymphatic system. The findings in this study reveal the impaired Mfsd2a and Aqp4 expression and Aqp4 perivascular mislocalization in retinal blood vessels during physiological (WT) and pathological (5xFAD) aging, indicating their importance as putative targets for the development of new treatments that can improve the regulation of transcytosis or the function of the glymphatic system.

Amyloid-ß plaque formation and BACE1 accumulation in the brains of a 5xFAD Alzheimer's disease mouse model is associated with altered distribution and not proteolysis of BACE1 substrates Sez6 and Sez6L

The formation of amyloid-ß peptides (Aß), that accumulate in Alzheimer's disease (AD) brains, involves proteolytic processing of the amyloid precursor protein (APP) firstly by ß-secretase (BACE1). Since BACE1 cleaves a plethora of other substrates, in this work we investigated whether the proteolysis and/or distribution of other BACE1 substrates, such as seizure protein 6 (Sez6) and seizure 6-like protein (Sez6L), is altered in AD. To test this we used 5xFAD mouse model brains that show an early accumulation of Aß plaques already at 2-months of age. Here we show for the first time that accumulation of BACE1 in peri-plaque regions and its enhanced levels in AD brains does not affect proteolysis of BACE1 substrates other than APP, such as Sez6 and Sez6L. We observed altered distribution of Sez6 and Sez6L in the area of Aß plaques in 5xFAD brains which is distinct to that of APP, BACE1 and/or LAMP1, suggesting different localization and/or function of these BACE1 substrates. While it is necessary to further elucidate the potential role that this may play in the course of AD, it is likely that Aß-targeted therapies may have beneficial effects against accumulation and/or altered distribution of BACE1 and its substrates, in addition to APP.

Food Restriction Counteracts Dexamethasone-Induced Downregulation of Genes Involved in Cholesterol Homeostasis in Rat Brain during Aging

Glucocorticoids are the most potent anti-inflammatory agents known. Limited in vivo data are available to characterize the mechanism underlying their cognitive side effects and transient occurrence of steroid psychosis. Cholesterol is important for proper neurotransmission and brain plasticity, and disruption of its homeostasis in the brain has been closely associated with memory decline during aging and in age-related neurodegenerative disorders. In the present study, we assessed the direct effects of dexamethasone, a potent synthetic glucocorticoid, on the expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), apolipoprotein E (ApoE) and cholesterol 24S-hydroxylase (CYP46A1), major enzymes involved in cholesterol synthesis, metabolism, and excretion, respectively. The effects of the dexamethasone were examined during aging, in the cortex and hippocampus of 6-, 12- and 18-month-old rats, and following long-term food restriction (FR). The most prominent change observed was the age-related decrease in ApoE mRNA regardless of the food regimen applied. In animals kept on FR, this decrease was accompanied by an increase in the mRNA expression of HMGCR and CYP46A1. The present study also demonstrates that food restriction reversed most of the dexamethasone-induced changes in the expression of genes involved in regulation of cholesterol homeostasis in aging rats, in a region-specific manner.

Corticosterone and Glucocorticoid Receptor in the Cortex of Rats during Aging-The Effects of Long-Term Food Restriction

Numerous beneficial effects of food restriction on aging and age-related pathologies are well documented. It is also well-established that both short- and long-term food restriction regimens induce elevated circulating levels of glucocorticoids, stress-induced hormones produced by adrenal glands that can also exert deleterious effects on the brain. In the present study, we examined the effect of long-term food restriction on the glucocorticoid hormone/glucocorticoid receptor (GR) system in the cortex during aging, in 18- and 24-month-old rats. Corticosterone level was increased in the cortex of aged ad libitum-fed rats. Food restriction induced its further increase, accompanied with an increase in the level of 11β-hydroxysteroid dehydrogenase type 1. However, alterations in the level of GR phosphorylated at Ser²³² were not detected in animals on food restriction, in line with unaltered CDK5 level, the decrease of Hsp90, and an increase in a negative regulator of GR function, FKBP51. Moreover, our data revealed that reduced food intake prevented age-related increase in the levels of NFκB, gfap, and bax, confirming its anti-inflammatory and anti-apoptotic effects. Along with an increase in the levels of c-fos, our study provides additional evidences that food restriction affects cortical responsiveness to glucocorticoids during aging.

Altered hedonic, novelty-, stress- and D-amphetamine-induced response due to social isolation in peripuberty

Reduction in direct social contact with peers during early adolescence is thought to be a risk factor for an increase in depressive symptoms, but there is still no clear evidence to suggest early behavioral manifestations and their association with the later outcome of social distancing during this period. To address this question, we used social isolation paradigm in peripubertal rats as the rodent model of adolescence. The litter was an experimental unit. On postnatal day 29, each litter gave group-housed and single-housed males, which were reared and tested one week and two weeks thereafter. Psychomotor/emotional response to novelty in exploration-based tasks, behavioral and neuronal responses to the drug reward (D-amphetamine), motivation/hedonic behavior, physiological and response to physiological stress were examined. Social isolation in peripubertal rats manifested through: hyper-reactivity/agitation and the state anxiety/risk-taking at an early stage; reduced behavioral response to D-amphetamine and altered neural processing of this stimulus, at a later stage; consummatory hypohedonia that deepened over time without changing the motivation to eat; unchanged body weight gain and resting blood corticosterone, cortisol and glucose levels over time; altered blood biochemistry (silenced corticosterone and increased glucose) due to overnight fasting only at an early stage. Our results highlight that the outcome of reduced direct social contact with peers during peripuberty is dynamic, with the cluster of atypical early symptoms that evolve into the syndrome that is delicate for assessment through routinely measurable behavior and biomarkers of stress, but with progressive consummatory hypohedonia and unaffected motivation to eat as stable marks.

In Vivo/Ex Vivo EPR Investigation of the Brain Redox Status and Blood-Brain Barrier Integrity in the 5xFAD Mouse Model of Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is the most common neurodegenerative disorder characterized by cognitive decline and total brain atrophy. Despite the substantial scientific effort, the pathological mechanisms underlying neurodegeneration in AD are currently unknown. In most studies, amyloid β peptide has been considered the key pathological change in AD. However, numerous Aβ-targeting treatments have failed in clinical trials. This implies the need to shift the research focus from Aβ to other pathological features of the disease.

OBJECTIVE

The aim of this study was to examine the interplay between mitochondrial dysfunction, oxidative stress and blood-brain barrier (BBB) disruption in AD pathology, using a novel approach that involves the application of electron paramagnetic resonance (EPR) spectroscopy.

METHODS

In vivo and ex vivo EPR spectroscopy using two spin probes (aminoxyl radicals) exhibiting different cell-membrane and BBB permeability were employed to assess BBB integrity and brain tissue redox status in the 5xFAD mouse model of AD. In vivo spin probe reduction decay was analyzed using a two-compartment pharmacokinetic model. Furthermore, 15 K EPR spectroscopy was employed to investigate the brain metal content.

RESULTS

This study has revealed an altered brain redox state, BBB breakdown, as well as ROS-mediated damage to mitochondrial iron-sulfur clusters, and up-regulation of MnSOD in the 5xFAD model.

CONCLUSION

The EPR spin probes were shown to be excellent in vivo reporters of the 5xFAD neuronal tissue redox state, as well as the BBB integrity, indicating the importance of in vivo EPR spectroscopy application in preclinical studies of neurodegenerative diseases.

Pharmacological intervention in a transgenic mouse model improves Alzheimer's-associated pathological phenotype: Involvement of proteasome activation

Alzheimer's disease (AD) is the most common form of dementia worldwide, characterized by a progressive decline in a variety of cognitive and non-cognitive functions. The amyloid beta protein cascade hypothesis places the formation of amyloid beta protein aggregates on the first position in the complex pathological cascade leading to neurodegeneration, and therefore AD might be considered to be a protein-misfolding disease. The Ubiquitin Proteasome System (UPS), being the primary protein degradation mechanism with a fundamental role in the maintenance of proteostasis, has been identified as a putative therapeutic target to delay and/or to decelerate the progression of neurodegenerative disorders that are characterized by accumulated/aggregated proteins. The purpose of this study was to test if the activation of proteasome in vivo can alleviate AD pathology. Specifically by using two compounds with complementary modes of proteasome activation and documented antioxidant and redox regulating properties in the 5xFAD transgenic mice model of AD, we ameliorated a number of AD related deficits. Shortly after proteasome activation we detected significantly reduced amyloid-beta load correlated with improved motor functions, reduced anxiety and frailty level. Essentially, to our knowledge this is the first report to demonstrate a dual activation of the proteasome and its downstream effects. In conclusion, these findings open up new directions for future therapeutic potential of proteasome-mediated proteolysis enhancement.

Neuroprotective effects of food restriction in a rat model of traumatic brain injury - the role of glucocorticoid signaling

OBJECTIVE

Traumatic brain injury (TBI) is one of the most common causes of neurological damage in young and middle aged people. Food restriction (FR) has been shown to act neuroprotectively in animal models of stroke and TBI. Indeed, our previous studies showed that FR attenuates inflammation, through suppression of microglial activation and TNF-α production, suppresses caspase-3-induced neuronal cell death and enhances neuroplasticity in the rat model of TBI. Glucocorticoids (GCs) play a central role in mediating both molecular and behavioral responses to food restriction. However, the exact mechanisms of FR neuroprotection in TBI are still unclear. The goal of the present study was to examine whether FR exerts its beneficial effects by altering the glucocorticoid receptor (GR) signaling alone and/or together with other protective factors.

METHODS

To this end, we examined the effects of FR (50% of regular daily food intake for 3 months prior to TBI) on the protein levels of total GR, GR phosphoisoform Ser232 (p-GR) and its transcriptional activity, as well as 11β-HSD1, NFκB (p65) and HSP70 as factors related to the GR signaling.

RESULTS

Our results demonstrate that FR applied prior to TBI significantly changes p-GR levels, and it's transcriptional activity during the recovery period after TBI. Moreover, as a pretreatment, FR modulates other protective factors in response to TBI, such as 11β-HSD1, NF-κB (p65) and HSP70 that act in parallel with GR in it's anti-inflammatory and neuroprotective effects in the rat model of brain injury.

CONCLUSION

Our results suggest that prophylactic FR represents a potent non-invasive approach capable of changing GR signalling, together with other factors related to the GR signaling in the model of TBI.

Motivation, risk-taking and sensation seeking behavior in propofol anesthesia exposed peripubertal rats

Adolescent neurodevelopment confer vulnerability to the actions of treatments that produce adaptations in neurocircuitry underlying motivation, impulsivity and reward. Considering wide usage of a sedative-hypnotic agent propofol in clinical practice, we examined whether propofol is a challenging treatment for peripubertal brain. Motivation/hedonic behavior (sucrose preference test), approach/avoidance behavior (elevated plus maze test) and response to dissociative drug phencyclidine (PCP) were studied in peripubertal rats (the rodent model of periadolescence) after propofol anesthesia exposure (PAE). Neurodegeneration (Fluoro-Jade staining) and the expression of proteins (Western blot) involved in excitatory synaptic transmission and activity-dependent synaptic stabilization in the medial prefrontal cortex (mPFC) and striatum (components of motivation/reward circuitry; process both appetitive and aversive events) were examined as well. In peripubertal rats PAE produced 1) transient brain-region specific changes in the expression of N-methyl-d-aspartate (NMDA) receptor subunits NR2A and NR2B, PSD-95 and N-cadherin, without neurotoxicity, 2) hyperlocomotor response to PCP, 3) no changes in preference for palatable 1% sucrose solution and a decrease in food eaten, 4) preference for 20% sucrose solution without changes in food eaten, 5) stretch-attended postures and open arms entries in the elevated plus maze test. Overall, these novel findings show that PAE leaves transient synaptic trace recognized as early form of synaptic plasticity related to passive drug exposure in the brain systems implicated in motivation/reward, increases drug-responsiveness, favors risk-taking and preference of novel/intense stimuli repairing otherwise present motivational deficiency. These findings accentuate multifaceted response to propofol in peripuberty and the importance of environmental stability for the most favorable neurobehavioral recovery.

Every-other-day feeding exacerbates inflammation and neuronal deficits in 5XFAD mouse model of Alzheimer's disease

Food restriction has been widely associated with beneficial effects on brain aging and age-related neurodegenerative diseases such as Alzheimer's disease. However, previous studies on the effects of food restriction on aging- or pathology-related cognitive decline are controversial, emphasizing the importance of the type, onset and duration of food restriction. In the present study, we assessed the effects of preventive every-other-day (EOD) feeding regimen on neurodegenerative phenotype in 5XFAD transgenic mice, a commonly used mouse model of Alzheimer's disease. EOD feeding regimen was introduced to transgenic female mice at the age of 2 months and the effects on amyloid-β (Aβ) accumulation, gliosis, synaptic plasticity, and blood-brain barrier breakdown were analyzed in cortical tissue of 6-month-old animals. Surprisingly, significant increase of inflammation in the cortex of 5XFAD fed EOD mice was observed, reflected by the expression of microglial and astrocytic markers. This increase in reactivity and/or proliferation of glial cells was accompanied by an increase in proinflammatory cytokine TNF-α, p38 MAPK and EAAT2, and a decrease in GAD67. NMDA receptor subunit 2B, related to glutamate excitotoxicity, was increased in the cortex of 5XFAD-EOD mice indicating additional alterations in glutamatergic signaling. Furthermore, 4 months of EOD feeding regimen had led to synaptic plasticity proteins reduction and neuronal injury in 5XFAD mice. However, EOD feeding regimen did not affect Aβ load and blood-brain barrier permeability in the cortex of 5XFAD mice. Our results demonstrate that EOD feeding regimen exacerbates Alzheimer's disease-like neurodegenerative and neuroinflammatory changes irrespective of Aβ pathology in 5XFAD mice, suggesting that caution should be paid when using food restrictions in the prodromal phase of this neurodegenerative disease.

Short-term fish oil supplementation applied in presymptomatic stage of Alzheimer's disease enhances microglial/macrophage barrier and prevents neuritic dystrophy in parietal cortex of 5xFAD mouse model

Dystrophic neurites and activated microglia are one of the main neuropathological characteristics of Alzheimer's disease (AD). Although the use of supplements with omega-3 fatty acids has been associated with reduced risk and lessened AD pathology, it still remains elusive whether such a treatment could affect dystrophic neurites (DNs) formation and microglia/macrophage behavior in the early phase of disease. We analyzed the effects of short-term (3 weeks) fish oil supplementation on DNs formation, tau hyperphosphorylation, Amyloid-beta peptide 1–42 (Aβ42) levels and microglial/macrophage response to AD pathology in the parietal cortex of 4-month-old 5xFAD mice, a mouse model of AD. The present study shows for the first time that short-term FO supplementation applied in presymptomatic stage of AD, alters the behaviour of microglia/macrophages prompting them to establish a physical barrier around amyloid plaques. This barrier significantly suppresses DNs formation through the reduction of both Aβ content and tau hyperphosphorylation. Moreover, the short-term FO treatment neither suppresses inflammation nor enhances phagocytic properties of microglia/macrophages in the response to Aβ pathology, the effects most commonly attributed to the fish oil supplementation. Our findings suggest that fish oil consumption may play an important role in modulating microglial/macrophage response and ameliorating the AD pathology in presymptomatic stage of Alzheimer's disease.

Impaired IL-17 Production in Gut-Residing Immune Cells of 5xFAD Mice with Alzheimer's Disease Pathology

Alzheimer's disease (AD) is characterized by accumulation of amyloid-β plaques that further promotes microglia-mediated neuroinflammatory responses and inflammation in the brain. Emerging data are revealing the relation between gut-associated lymphoid tissue (GALT) cells and CNS, as effector cells primed in the gut might home to the brain. This study aimed to determine cell composition of GALT in 5xFAD mice, an established model for AD. Immune cells isolated from Peyer's patches (PP) and mesenteric lymph nodes (MLN) were stained with surface and intracellular markers for T helper (Th) subpopulations, B lymphocytes and macrophages and analyzed cytofluorimetrically, while cytokine expression and production were determined by qPCR and ELISA, respectively. Inflammation was detected in GALT of 5xFAD mice with established AD pathology. Although the production of IFN-γ, IL-4, and IL-10 was comparable between the strains, lower IL-17 production was observed in PP and MLN cells. This phenomenon could not be attributed to a lower abundance of Th17 cells, or cytokines that initiate their formation or propagation (TGF-β, IL-6, and IL-23). Also, reduced IL-17 production was not a consequence of altered Il-17 mRNA transcription or deficiency of Rorγt, a key transcription factor for IL-17. However, the expression of miR-155 (a non-coding micro RNA that promotes the development of Th17 cells), was significantly lower in MLN cells of 5xFAD mice. In contrast, mice without AD neuropathology did not have inflammation in GALT or altered Th17 numbers, nor decreased IL-17 production. In conclusion, the observed changes in GALT of 5xFAD mice mirror the disease progression and might reflect inadequate immune surveillance in the gut and lead to enhanced AD pathology.

Short-Term Fish Oil Treatment Changes the Composition of Phospholipids While Not Affecting the Expression of Mfsd2a Omega-3 Transporter in the Brain and Liver of the 5xFAD Mouse Model of Alzheimer's Disease

Long-term fish oil (FO) supplementation is able to improve Alzheimer’s disease (AD) pathology. We aimed to determine the impact of short-term fish oil (FO) intake on phospholipids composition and plaque pathology in 5xFAD mice, a widely used animal model of AD. A 3-week-long FO supplementation administered at 3 months of age decreased the number of dense core plaques in the 5xFAD cortex and changed phospholipids in the livers and brains of wild-type (Wt) and 5xFAD mice. Livers of both genotypes responded by increase of n-3 and reciprocal decrease of n-6 fatty acids. In Wt brains, FO supplementation induced elevation of n-3 fatty acids and subsequent enhancement of n-6/n-3 ratio. However, in 5xFAD brains the improved n-6/n-3 ratio was mainly due to FO-induced decrease in arachidonic and adrenic n-6 fatty acids. Also, brain and liver abundance of n-3 fatty acids were strongly correlated in Wts, oppositely to 5xFADs where significant brain-liver correlation exists only for n-6 fatty acids. Expression of omega-3 transporter Mfs2a remained unchanged after FO supplementation. We have demonstrated that even a short-term FO intake improves the phospholipid composition and has a significant effect on plaque burden in 5xFAD brains when applied in early stages of AD pathology.

The influence of propofol anesthesia exposure on nonaversive memory retrieval and expression of molecules involved in memory process in the dorsal hippocampus in peripubertal rats

BACKGROUND

The effects of anesthetic drugs on postoperative cognitive function in children are not well defined and have not been experimentally addressed.

AIMS

The present study aimed to examine the influence of propofol anesthesia exposure on nonaversive hippocampus-dependent learning and biochemical changes involved in memory process in the dorsal hippocampus, in peripubertal rats as the rodent model of periadolescence.

METHODS

The intersession spatial habituation and the novel object recognition tasks were used to assess spatial and nonspatial, nonaversive hippocampus-dependent learning. The exposure to anesthesia was performed after comparably long acquisition phases in both tasks. Behavioral testing lasted for 2 consecutive days (24-hour retention period). Changes in the expression of molecules involved in memory retrieval/reconsolidation were examined in the dorsal hippocampus by Western blot and immunohistochemistry, at the time of behavioral testing.

RESULTS

Exposure to propofol anesthesia resulted in inappropriate assessment of spatial novelty at the beginning of the test session and affected continuation of acquisition in the spatial habituation test. The treatment did not affect recognition of the novel object at the beginning of the test session but it attenuated overall preference to novelty, reflecting retrieval of a weak memory. The expression of phosphorylated extracellular signal-regulated kinase 2 (involved in memory retrieval) was decreased while the level of phosphorylated Ca²⁺ /calmodulin-dependent protein kinase IIα and early growth response protein 1 (involved in memory reconsolidation) was increased in the dorsal hippocampus. The level of Finkel-Biskis-Jinkins murine osteosarcoma viral oncogene homolog B (neuronal activity indicator) was increased in the dorsal dentate gyrus. Enhanced exploratory activity was still evident in the propofol anesthesia exposure (PAE) group 48 hour after the treatment in both tasks.

CONCLUSION

In peripubertal rats, propofol anesthesia exposure affects memory retrieval and acquisition of new learning in the spatial and nonspatial, nonaversive learning tasks 24 hour after the treatment, along with the expression of molecules that participate in memory retrieval/reconsolidation in the dorsal hippocampus. These results may have clinical implications, favoring control of basic cognitive functions in older children after the propofol exposure.

Brain molecular changes and behavioral alterations induced by propofol anesthesia exposure in peripubertal rats

BACKGROUND

Propofol is commonly used in modern anesthesiology. Some findings suggest that it is highly addictive.

AIM

In this study it was examined whether propofol anesthesia exposure was able to induce behavioral alterations and brain molecular changes already described in addictive drug usage in peripubertal rats, during the onset of mid/periadolescence as a developmental period with increasing vulnerability to drug addiction.

METHODS

The expression of D1 dopamine receptor, a dopamine, and cAMP-regulated phosphoprotein with a Mr 32 000; Ca²⁺ /calmodulin-dependent protein kinase IIα; and Finkel-Biskis-Jinkins murine osteosarcoma viral oncogene homolog-B was examined in peripubertal rats 4, 24, and 48 hour after propofol anesthesia exposure by Western blot and immunohistochemistry. Brain regions of interest were the medial prefrontal cortex, the striatum, and the thalamus. Anxiety and behavioral cross-sensitization to d-amphetamine were examined as well.

RESULTS

Significant increase in the expression of dopamine and cAMP-regulated phosphoprotein with a Mr 32 000 phosphorylated at threonine 34, a postsynaptic marker of dopaminergic neurotransmission, and Finkel-Biskis-Jinkins murine osteosarcoma viral oncogene homolog-B, a marker of neuronal activity, was detected in the thalamus of experimental animals 4-24 hour after the treatment, with the accent on the paraventricular thalamic nucleus. Significant increase in the expression of Ca²⁺ /calmodulin-dependent protein kinase IIα phosphorylated at threonine 286, a sensor of synaptic activity, was observed in the prefrontal cortex and the striatum 24 hour after propofol anesthesia exposure. It was accompanied by a significant decrease in Finkel-Biskis-Jinkins murine osteosarcoma viral oncogene homolog-B expression in the striatum. Decreased behavioral inhibition in aversive environment and increased motor response to d-amphetamine in a context-independent manner were observed as well.

CONCLUSION

In peripubertal rats, propofol anesthesia exposure induces transient molecular and behavioral response that share similarities with those reported previously for addictive drugs. In the absence of additional pharmacological manipulation, all detected effects receded within 48 hour after the treatment.

Mannich bases of 1,2,4-triazole-3-thione containing adamantane moiety: Synthesis, preliminary anticancer evaluation, and molecular modeling studies

A series of 18 novel N-Mannich bases derived from 5-adamantyl-1,2,4-triazole-3-thione was synthesized and characterized using NMR spectroscopy and X-ray diffraction technique. All derivatives were evaluated for their anticancer potential against four human cancer cell lines. Several tested compounds exerted good cytotoxic activities on K562 and HL-60 cell lines, along with pronounced selectivity, showing lower cytotoxicity against normal fibroblasts MRC-5 compared to cancer cells. The effects of compounds 5b, 5e, and 5j on the cell cycle were investigated by flow cytometric analysis. It was found that these compounds cause the accumulation of cells in the subG1 and G1 phases of the cell cycle and induce caspase-dependent apoptosis, while the anti-angiogenic effects of 5b, 5e, and 5j have been confirmed in EA.hy926 cells using a tube formation assay. Further, the interaction of Bax protein with compound 5b was investigated by means of molecular modeling, applying the combined molecular docking/molecular dynamics approach.

Long-term intermittent feeding restores impaired GR signaling in the hippocampus of aged rat

Diminished glucocorticoid signaling is associated with an age-related decline in hippocampal functioning. In this study we demonstrate the effect of intermittent, every other day (EOD) feeding on the glucocorticoid hormone/glucocorticoid receptor (GR) system in the hippocampus of middle-aged (18-month-old) and aged (24-month-old) Wistar rats. In aged ad libitum-fed rats, a decrease in the level of total GR and GR phosphorylated at Ser(232) (pGR) was detected. Conversely, aged rats subjected to EOD feeding, starting from 6 months of age, showed an increase in GR and pGR levels and a higher content of hippocampal corticosterone. Furthermore, prominent nuclear staining of pGR was observed in CA1 pyramidal and DG granule neurons of aged EOD-fed rats. These changes were accompanied by increased Sgk-1 and decreased GFAP transcription, pointing to upregulated transcriptional activity of GR. EOD feeding also induced an increase in the expression of the mineralocorticoid receptor. Our results reveal that intermittent feeding restores impaired GR signaling in the hippocampus of aged animals by inducing rather than by stabilizing GR signaling during aging.

Long-term dietary restriction differentially affects the expression of BDNF and its receptors in the cortex and hippocampus of middle-aged and aged male rats

Dietary restriction (DR) exerts significant beneficial effects in terms of aging and age-related diseases in many organisms including humans. The present study aimed to examine the influence of long-term DR on the BDNF system at the transcriptional and translational levels in the cortex and hippocampus of middle-aged (12-month-old) and aged (24-month-old) male Wistar rats. The obtained results revealed that the DR upregulated the expression of exon-specific BDNF transcripts in both regions, followed by elevated levels of mBDNF only in the cortex in middle-aged animals. In aged animals, DR modulated BDNF protein levels by increasing proBDNF and by declining mBDNF levels. Additionally, elevated levels of the full-length TrkB accompanied by a decreased level of the less-glycosylated TrkB protein were observed in middle-aged rats following DR, while in aged rats, DR amplified only the expression of the less-glycosylated form of TrkB. The levels of phosphorylated TrkB(Y816) were stable during aging regardless of feeding. Reduced levels of p75(NTR) were detected in both regions of middle-aged DR-fed animals, while a significant increase was measured in the cortex of aged DR-fed rats. These findings shed additional light on DR as a modulator of BDNF system revealing its disparate effects in middle-aged and aged animals. Given the importance of the proBDNF/BDNF circuit-level expression in different brain functions and various aspects of behavior, it is necessary to further elucidate the optimal duration of the applied dietary regimen with regard to the animal age in order to achieve its most favorable effects.

Cholesterol metabolism changes under long-term dietary restrictions while the cholesterol homeostasis remains unaffected in the cortex and hippocampus of aging rats

Maintaining cholesterol homeostasis in the brain is vital for its proper functioning. While it is well documented that dietary restriction modulates the metabolism of cholesterol peripherally, little is known as to how it can affect cholesterol metabolism in the brain. The present study was designed to elucidate the impact of long-term dietary restriction on brain cholesterol metabolism. Three-month-old male Wistar rats were exposed to long-term dietary restriction until 12 and 24 months of age. The concentrations of cholesterol, its precursors and metabolites, and food-derived phytosterols were measured in the serum, cortex, and hippocampus by gas chromatography/mass spectrometry. Relative changes in the levels of proteins involved in cholesterol synthesis, transport, and degradation were determined by Western blot analysis. Reduced food intake influenced the expression patterns of proteins implicated in cholesterol metabolism in the brain in a region-specific manner. Dietary restriction decreased the concentrations of cholesterol precursors, lanosterol in the cortex, and lanosterol and lathosterol in the hippocampus at 12 months, while the level of desmosterol was elevated in the hippocampus at 24 months. The concentrations of cholesterol and 24(S)-hydroxycholesterol remained unaffected. Food-derived phytosterols were significantly lower after dietary restriction in both the cortex and hippocampus at 12 and 24 months. These findings provide new insight into the effects of dietary restriction on cholesterol metabolism in the brain, lending further support to its neuroprotective effect.

Propofol anesthesia induces proapoptotic tumor necrosis factor-α and pro-nerve growth factor signaling and prosurvival Akt and XIAP expression in neonatal rat brain

Previously we observed that prolonged exposure to propofol anesthesia causes caspase-3- and calpain-mediated neuronal death in the developing brain. The present study examines the effects of propofol anesthesia on the expression of tumor necrosis factor-α (TNFα), pro-nerve growth factor (NGF), and their receptors in the cortex and the thalamus. We also investigated how propofol influences the expression of Akt and X-linked inhibitor of apoptosis (XIAP) expression, proteins that promote prosurvival pathways. Seven-day-old rats (P7) were exposed to propofol anesthesia lasting 2, 4, or 6 hr and killed 0, 4, 16, or 24 hr after anesthesia termination. The relative levels of mRNA and protein expression were estimated by RT-PCR and Western blot analysis, respectively. The treatments caused marked activation of TNFα and its receptor TNFR-1 and pro-NGF and p75(NTR) receptor expression. In parallel with the induction of these prodeath signals, we established that propofol anesthesia promotes increased expression of the prosurvival molecules pAkt and XIAP during the 24-hr postanesthesia period. These results show that different brain structures respond to propofol anesthesia with a time- and duration of exposure-dependent increase in proapoptotic signaling and with concomitant increases in activities of prosurvival proteins. We hypothesized that the fine balance between these opposing processes sustains homeostasis in the immature rat brain and prevents unnecessary damage after exposure to an injurious stimulus. The existence of this highly regulated process provides a time frame for potential therapeutic intervention directed toward suppressing the deleterious component of propofol anesthesia.

BDNF transcripts, proBDNF and proNGF, in the cortex and hippocampus throughout the life span of the rat

Neurotrophins are established molecular mediators of neuronal plasticity in the adult brain. We analyzed the impact of aging on brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) protein isoforms, their receptors, and on the expression patterns of multiple 5' exon-specific BDNF transcripts in the rat cortex and hippocampus throughout the life span of the rat (6, 12, 18, and 24 months of age). ProNGF was increased during aging in both structures. Mature NGF gradually decreased in the cortex, and, in 24-month-old animals, it was 30% lower than that in adult 6-month-old rats. The BDNF expression did not change during aging, while proBDNF accumulated in the hippocampus of aged rats. Hippocampal total BDNF mRNA was lower in 12-month-old animals, mostly as a result of a decrease of BDNF transcripts 1 and 2. In contrast to the region-specific regulation of specific exon-containing BDNF mRNAs in adult animals, the same BDNF RNA isoforms (containing exons III, IV, or VI) were present in both brain structures of aged animals. Deficits in neurotrophin signaling were supported by the observed decrease in Trk receptor expression which was accompanied by lower levels of the two main downstream effector kinases, pAkt and protein kinase C. The proteolytic processing of p75NTR observed in 12-month-old rats points to an additional regulatory mechanism in early aging. The changes described herein could contribute to reduced brain plasticity underlying the age-dependent decline in cognitive function.

Aging induces tissue-specific changes in cholesterol metabolism in rat brain and liver

Disturbance of cholesterol homeostasis in the brain is coupled to age-related brain dysfunction. In the present work, we studied the relationship between aging and cholesterol metabolism in two brain regions, the cortex and hippocampus, as well as in the sera and liver of 6-, 12-, 18- and 24-month-old male Wistar rats. Using gas chromatography-mass spectrometry, we undertook a comparative analysis of the concentrations of cholesterol, its precursors and metabolites, as well as dietary-derived phytosterols. During aging, the concentrations of the three cholesterol precursors examined (lanosterol, lathosterol and desmosterol) were unchanged in the cortex, except for desmosterol which decreased (44 %) in 18-month-old rats. In the hippocampus, aging was associated with a significant reduction in lanosterol and lathosterol concentrations at 24 months (28 and 25 %, respectively), as well as by a significant decrease of desmosterol concentration at 18 and 24 months (36 and 51 %, respectively). In contrast, in the liver we detected age-induced increases in lanosterol and lathosterol concentrations, and no change in desmosterol concentration. The amounts of these sterols were lower than in the brain regions. In the cortex and hippocampus, desmosterol was the predominant cholesterol precursor. In the liver, lathosterol was the most abundant precursor. This ratio remained stable during aging. The most striking effect of aging observed in our study was a significant decrease in desmosterol concentration in the hippocampus which could reflect age-related reduced synaptic plasticity, thus representing one of the detrimental effects of advanced age.

Induced Resistance in the Human Non Small Cell Lung Carcinoma (NCI-H460) Cell Line In Vitro by Anticancer Drugs

Exposure of human non-small cell lung cancer cells (NCI-H460) to gradually increasing concentrations of doxorubicin resulted in the appearance of a new cell line (NCI-H460/R) that was resistant to doxorubicin (96.2-fold) and cross-resistant to etoposide, paclitaxel, vinblastine and epirubicin. Slight cross-resistance to two MDR-unrelated drugs 8-Cl-cAMP and sulfinosine was observed. Flow cytometry analysis showed that the accumulation of doxorubicin in the resistant cells was 88.4% lower than in the parental cells. Also, verapamil significantly decreased the efflux rate in NCI-H460 and NCI-H460/R cells, whereas curcumin inhibited the efflux in NCI-H460 cells only. Gene expression data confirmed the induction of mdr1 (P-gp), as judged by the observed 15-fold increase in its mRNA concentration in doxorubicin-resistant NCI-H460/R cells. In contrast, mrp1 and lrp expression was unaffected by the doxorubicin resistance. Further work should develop a rationale for a novel treatment of NSCLC with appropriate modulators of resistance aimed at improving the outcome of the acquired drug resistance.

Caloric restriction suppresses microglial activation and prevents neuroapoptosis following cortical injury in rats

Traumatic brain injury (TBI) is a widespread cause of death and a major source of adult disability. Subsequent pathological events occurring in the brain after TBI, referred to as secondary injury, continue to damage surrounding tissue resulting in substantial neuronal loss. One of the hallmarks of the secondary injury process is microglial activation resulting in increased cytokine production. Notwithstanding that recent studies demonstrated that caloric restriction (CR) lasting several months prior to an acute TBI exhibits neuroprotective properties, understanding how exactly CR influences secondary injury is still unclear. The goal of the present study was to examine whether CR (50% of daily food intake for 3 months) alleviates the effects of secondary injury on neuronal loss following cortical stab injury (CSI). To this end, we examined the effects of CR on the microglial activation, tumor necrosis factor-α (TNF-α) and caspase-3 expression in the ipsilateral (injured) cortex of the adult rats during the recovery period (from 2 to 28 days) after injury. Our results demonstrate that CR prior to CSI suppresses microglial activation, induction of TNF-α and caspase-3, as well as neurodegeneration following injury. These results indicate that CR strongly attenuates the effects of secondary injury, thus suggesting that CR may increase the successful outcome following TBI.

Propofol-induced changes in neurotrophic signaling in the developing nervous system in vivo

Several studies have revealed a role for neurotrophins in anesthesia-induced neurotoxicity in the developing brain. In this study we monitored the spatial and temporal expression of neurotrophic signaling molecules in the brain of 14-day-old (PND14) Wistar rats after the application of a single propofol dose (25 mg/kg i.p). The structures of interest were the cortex and thalamus as the primary areas of anesthetic actions. Changes of the protein levels of the brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), their activated receptors tropomyosin-related kinase (TrkA and TrkB) and downstream kinases Akt and the extracellular signal regulated kinase (ERK) were assessed by Western immunoblot analysis at different time points during the first 24 h after the treatment, as well as the expression of cleaved caspase-3 fragment. Fluoro-Jade B staining was used to follow the appearance of degenerating neurons. The obtained results show that the treatment caused marked alterations in levels of the examined neurotrophins, their receptors and downstream effector kinases. However, these changes were not associated with increased neurodegeneration in either the cortex or the thalamus. These results indicate that in the brain of PND14 rats, the interaction between Akt/ERK signaling might be one of important part of endogenous defense mechanisms, which the developing brain utilizes to protect itself from potential anesthesia-induced damage. Elucidation of the underlying molecular mechanisms will improve our understanding of the age-dependent component of anesthesia-induced neurotoxicity.

Changes of behavioral parameters during long-term food restriction in middle-aged Wistar rats

Food restriction (FR) has a beneficial effect on aging process and exerts a significant effect on the responses of rodents to standard behavioral tasks. The aim of this study was to assess the cumulative influence of FR on the behavioral and biochemical parameters in Wistar rats. Six-month-old rats were subjected to restrictive feeding (50% of the daily food intake, every-other-day feeding regimen) for one month or for six months until ages of 7 and 12months, respectively. We examined the habituation of exploratory movement, amphetamine (AMPH)-induced motor activity, as well as changes in serum corticosterone (CORT) and glucose levels. The results obtained from FR animals were compared with ad libitum (AL)-fed age-matched control rats. Habituation of motor activity was only affected by six months of restrictive feeding. The sensitization of the motor response to AMPH that was observed in animals exposed to FR for one month was not observed in animals that were exposed to the same feeding regimen for six months. Serum CORT was increased and serum glucose was decreased in both FR groups. These results clearly show that despite the similarity of the biochemical changes that were induced by one and six months of FR, the nature of the changes in motor activities in these two groups of animals during habituation and after AMPH treatment was different. Our findings indicate that long-term FR has complex behavioral consequences that need to be carefully evaluated with respect to animal age, duration of FR and severity of the diet.

Regional and temporal profiles of calpain and caspase-3 activities in postnatal rat brain following repeated propofol administration

Exposure of newborn rats to a variety of anesthetics has been shown to induce apoptotic neurodegeneration in the developing brain. We investigated the effect of the general anesthetic propofol on the brain of 7-day-old (P7) Wistar rats during the peak of synaptic growth. Caspase and calpain protease families most likely participate in neuronal cell death. Our objective was to examine regional and temporal patterns of caspase-3 and calpain activity following repeated propofol administration (20 mg/kg). P7 rats were exposed for 2, 4 or 6 h to propofol and killed 0, 4, 16 and 24 h after exposure. Relative caspase-3 and calpain activities were estimated by Western blot analysis of the proteolytic cleavage products of α-II-spectrin, protein kinase C and poly(ADP-ribose) polymerase 1. Caspase-3 activity and expression displayed a biphasic pattern of activation. Calpain activity changed in a region- and time-specific manner that was distinct from that observed for caspase-3. The time profile of calpain activity exhibited substrate specificity. Fluoro-Jade B staining revealed an immediate neurodegenerative response that was in direct relationship to the duration of anesthesia in the cortex and inversely related to the duration of anesthesia in the thalamus. At later post-treatment intervals, dead neurons were detected only in the thalamus 24 h following the 6-hour propofol exposure. Strong caspase-3 expression that was detected at 24 h was not followed by cell death after 2- and 4-hour exposures to propofol. These results revealed complex patterns of caspase-3 and calpain activities following prolonged propofol anesthesia and suggest that both are a manifestation of propofol neurotoxicity at a critical developmental stage.

Brain injury induces cholesterol 24-hydroxylase (Cyp46) expression in glial cells in a time-dependent manner

Maintaining the cholesterol homeostasis is essential for normal CNS functioning. The enzyme responsible for elimination of cholesterol excess from the brain is cholesterol 24-hydroxylase (Cyp46). Since cholesterol homeostasis is disrupted following brain injury, in this study we examined the effect of right sensorimotor cortex suction ablation on cellular and temporal pattern of Cyp46 expression in the rat brain. Increased expression of Cyp46 at the lesion site at all post injury time points (2, 7, 14, 28 and 45 days post injury, dpi) was detected. Double immunofluorescence staining revealed colocalization of Cyp46 expression with different types of glial cells in time-dependent manner. In ED1(+) microglia/macrophages Cyp46 expression was most prominent at 2 and 7 dpi, whereas Cyp46 immunoreactivity persisted in reactive astrocytes throughout all time points post-injury. However, during the first 2 weeks Cyp46 expression was enhanced in both GFAP(+) and Vim(+) astrocytes, while at 28 and 45 dpi its expression was mostly associated with GFAP(+) cells. Pattern of neuronal Cyp46 expression remained unchanged after the lesion, i.e. Cyp46 immunostaining was detected in dendrites and cell body, but not in axons. The results of this study clearly demonstrate that in pathological conditions, like brain injury, Cyp46 displayed atypical expression, being expressed not only in neuronal cells, but also in microglia and astrocytes. Therefore, injury-induced expression of Cyp46 in microglial and astroglial cells may be involved in the post-injury removal of damaged cell membranes contributing to re-establishment of the brain cholesterol homeostasis.

Long-term dietary restriction modulates the level of presynaptic proteins in the cortex and hippocampus of the aging rat

Brain aging is related to the numerous structural and functional changes including decreased synaptic plasticity. The beneficial effects of dietary restriction (DR) are well known but insufficiently investigated at the level of plasticity-related markers. Therefore, the aim of this study was to examine the expression profiles of proteins structurally and functionally related to synapses-growth-associated protein 43 (GAP-43), synaptophysin (SPH) and alpha-synuclein (alpha-Syn), in the course of aging and in response to long-term DR. The mRNA and protein levels of three presynaptic proteins were assessed by Real Time RT-PCR and Western blotting in the cortex and hippocampus of young (6-month-old), middle-aged (12-month-old), aged (18-month-old) and old (24-month-old) male Wistar rats fed ad libitum and exposed to DR starting from 6 months of age. We observed that long-term DR modulated age-related transcriptional changes by maintaining stable mRNAs levels in the cortex. No major age-related changes of the protein levels were observed in the cortex, while the specific temporal decline was detected in the hippocampus for all three proteins. The SPH levels were decreased across lifespan (0.8-, 0.8- and 0.6-fold change at 12, 18 and 24 months), while the significant decrease of GAP-43 and alpha-Syn protein was detected at 24 months of age (0.6- and 0.7-fold decrease, respectively). Long-term DR eliminated this decline by increasing GAP-43, SPH and alpha-Syn protein levels (1.7-, 1.7- and 1.6-fold, respectively) thus reverting protein levels to the values measured in 6-month-old animals.Specific pattern of changes observed in the hippocampus identifies this structure as more vulnerable to the processes of aging and with a more pronounced response to the DR effects. The observed DR-induced stabilization of the levels of three presynaptic proteins indicates the beneficial effect of DR on age-related decline in the capacity for synaptic plasticity.

Potential mechanism of cell death in the developing rat brain induced by propofol anesthesia

Commonly used general anesthetics can have adverse effects on the developing brain by triggering apoptotic neurodegeneration, as has been documented in the rat. The rational of our study was to examine the molecular mechanisms that contribute to the apoptotic action of propofol anesthesia in the brain of 7-day-old (P7) rats. The down-regulation of nerve growth factor (NGF) mRNA and protein expression in the cortex and thalamus at defined time points between 1 and 24h after the propofol treatment, as well as a decrease of phosphorylated Akt were observed. The extrinsic apoptotic pathway was induced by over-expression of tumor necrosis factor (TNF) which led to the activation of caspase-3 in both examined structures. Neurodegeneration was confirmed by Fluoro-Jade B staining. Our findings provide direct experimental evidence that the anesthetic dose (25mg/kg) of propofol induces complex changes that are accompanied by cell death in the cortex and thalamus of the developing rat brain.

Dietary restriction modulates alpha-synuclein expression in the aging rat cortex and hippocampus

Dietary restriction (DR) is one of the promising environmental interventions known to attenuate aging and decrease risk of age-related neurodegenerative disorders. The aim of this study was to assess the effects of DR on expression of alpha-synuclein, a presynaptic protein involved in pathogenesis of Parkinson's and some other neurodegenerative diseases, in the cortex and hippocampus of adult, middle-aged, late middle-aged, and aged rats. Using Real Time RT-PCR, the authors report that aging regulates the expression of alpha-synuclein in a tissue-specific manner and that long-term DR reverts the late age-related changes of alpha-synuclein expression.

Effects of aging, dietary restriction and glucocorticoid treatment on housekeeping gene expression in rat cortex and hippocampus-evaluation by real time RT-PCR

Accurate normalization is the prerequisite for obtaining reliable results in the quantification of gene expression. Using TaqMan Real Time RT-PCR, we carried out an extensive evaluation of five most commonly used endogenous controls, gapdh, beta-actin, 18S rRNA, hprt and cypB, for their presumed stability of expression, in rat cortex and hippocampus, during aging, under dietary restriction and dexamethasone treatment. Valid reference genes (HKGs) were identified using GeNorm and NormFinder software packages and by direct comparison of Ct values. Analysis revealed gapdh and beta-actin as the most stable HKGs for all treatments analyzed, combined or separately, in the cortex, while in the hippocampus gapdh/hprt and beta-actin/hprt are the combination of choice for the single or combined effects of dietary restriction/dexamethasone, respectively. All treatments significantly influenced expression of 18S rRNA and cypB in both structures. In addition, we used gapdh and normalization factor, calculated by GeNorm, to compare the expression of alpha-syn in the cortex. Our results demonstrate the importance of the right choice of HKG and suggest the appropriate endogenous control to be used for TaqMan RT-PCR analysis of mRNA expression in rat cortex and hippocampus for selected experimental paradigms.

Behavioral and biochemical effects of various food-restriction regimens in the rats

In this paper we describe the effects of six different food restriction (FR) regimens on amphetamine (AMPH)-induced locomotor and nonlocomotor activities in male rats. Changes in serum corticosterone (CORT), insulin and glucose levels were also examined. Each regimen was implemented through different daily food allowance (50%, 25% and 12.5% of the daily food intake, referred to as 50%, 75% and 87.5% FR groups, respectively) and by a specific feeding regimen - either every day (ED) or every other day (EOD). AMPH injection led to a significant increase of locomotor activity in all rats subjected to FR compared to ad libitum fed rats. A significant increase of nonlocomotor activity was observed only in the 75% FR and 87.5% FR groups. The serum CORT levels were significantly elevated and the serum insulin and glucose levels were significantly decreased in all of the FR groups in comparison to the AL rats. The results presented in this paper suggest that the ED regimens produced changes in motor activity and biochemical parameters, which were more-or-less dependent on the degree of FR. In contrast, the EOD regimens induced very similar changes irrespective of the degree of FR degree. Our data support the possible mechanistic roles of CORT and insulin in the effect of FR on locomotor activity, since the most pronounced increase of serum CORT and more pronounced decrease in serum insulin concentration was observed in the groups that also exhibited the highest locomotor activities.