Modulation of apoptotic signaling pathways in brain cells of adult male rats after chronic dexamethasone treatment

Deksametazon, jak sintetski glukokortikoid, se dugi niz godina koristi kao lek u tretmanu različitih bolesti poput psorijaze, adrenalne insuficijencije, bakterijalnog meningitisa, moždanih trauma, šloga, alergija, spazma bronhija, reumatidnog artritisa, itd; ali i kao pomoćni lek u hemo- i radioterapiji. Brojne studije ukazuju da deksametazon može regulisati sinaptičku plastičnost, povećati vijabilnost ćelija i njihovu proliferaciju u in vivo i in vitro uslovima. Međutim, uprkos širokoj primeni u terapijske svrhe primećeno je da deksametazon ispoljava i niz negativnih efekata u mozgu, na primer apoptozu u granularnom sloju dentatnog girusa hipokampusa kod mladih i starih pacova, kao i smanjenje kognitivnih funkcija i motornog razvoja. Usled neusklađenosti rezultata mnogih studija, proučavanje sistemskih efekata, kao i efekata deksametazona u mozgu predstavljaju interesantno polje istraživanja prvenstveno jer se efekti niskih doza ovog sintetskog glukokortikoida ne mogu ispitivati centralno usled blokiranja njegovog ulaska dejstvom MDR p-glikoproteina i/ili nekim drugim mehanizmom. Stoga, za potrebe eksperimenta, odrasli mužjaci pacova Wistar soja su podeljeni u dve grupe– kontrolne jedinke i životinje tretirane deksametazonom (100 g/kg/dan) tokom 7 uzastopnih dana. 28 h nakon završetka hroničnog tretmana životinje su žrtvovane. Sistemski efekat deksametazona je praćen promenom biometrijskih parametara (telesna masa, masa timusa i nadbubrežnih žlezdi), kao i koncentracije kortikosterona u serumu i moždanom tkivu. Kako bi se utvrdilo da li male doze deksametazona dovode do apoptoze u hipofizi, hipotalamusu, hipokampusu i prečeonoj kori korišćen je DNK fragmentacioni esej, dok se metodama histološkog bojenja hipokampusa i prečeone kore (fluoro-jade B i krezil ljubičastim) istraživao obim neuralne smrti i morfološke promene. Western blot i RT-PCR analizama su ispitivane promene u ekspresiji proteina i iRNK markera procesa smrti odnosno preživljavanja ćelija. Rezultati ove studije su pokazali da hroničan tretman malim dozama deksametazona uzrokuje hipoaktivnost hipotalamo-hipofizno-adrenalne ose, koja se ogleda u smanjenju telesne mase, mase timusa i nadbubrežnih žlezdi, kao i kortikosterona u serumu...For many years, dexamethasone, a potent synthetic glucocorticoid, has been used as a medication in the treatment of psoriasis, adrenal insufficiency, bacterial meningitis, brain trauma, stroke, allergies, bronchial spasm, rheumatoid arthritis, etc., and as a co-medicament in chemo- and radiotherapy. Numerous studies suggest that dexamethasone is able to regulate synaptic plasticity, enhance cell viability and proliferation in vivo and in vitro. However, dexamethasone exerts a number of adverse reactions in the brain, such as apoptosis in the hippocampal granular layer of dentate gyrus in young and old rats, as well as reduced cognitive and motor development. The dexamethasone-induced systemic effects and dexamethasone-provoked effects in the brain are an interesting field of research, mainly because the effects of low-dose dexamethasone treatment could not be tested directly in brain tissue due to the central blocking action of MDR p-glycoprotein and/or some other mechanism. Therefore, for the purposes of the experiment, adult male Wistar rats were divided into two groups – controls and animals treated with dexamethasone (100 g/kg/day) per 7 days. 28 h upon chronic treatment, rats from both groups were sacrificed. Late systemic effects of dexamethasone were monitored by alterations of biometric parameters (body weight, thymus and adrenal glands mass) and level of corticosterone in serum and brain tissue. Further, using DNA fragmentation assay, present study aimed to determine whether low dose dexamethasone treatment is able to cause apoptosis in the pituitary gland, hypothalamus, hippocampus and prefrontal cortex, while histological staining methods (fluoro-jade B and cresyl violet staining) were applied to investigated the extent of neuronal death and morphological changes in hippocampus and prefrontal cortex. Changes in protein and mRNA expression of cell death and cell survival markers were examined by Western blot and RT-PCR analyzes. The results obtained in this thesis revealed that chronic low dose dexamethasone treatment caused hypoactivity of hypothalamus-pituitary-adrenal axis, reflected in the reduction of body weight, thymus and adrenal glands masses, as well as levels of corticosterone in serum...

Early effects of ionizing ir-radiation on the ecto- 5'nucleotidase activity in rat brain during postnatal development

In the present study, early effects of low (50 cGy) and therapeutic dose (2 Gy) of ionizing γ-irradiation on ecto-5’nucleotidase activity in rat brain neuronal cells during postnatal development were studied. Ecto-5’-nucleotidase is the major enzyme that hydrolyzes extracellular AMP and is responsible for the formation of the P1 receptor agonist-adenosine. It was shown that the levels of AMP hydrolyses by the enzyme were not affected by irradiation in the rats during first 4 postnatal weeks. A both low- and therapeutic dose significantly decreased hydrolyses of extracellular AMP in pubertal and adult rats by 10-14%. These findings indicate that low dose exerts the same effects on ecto-5'nucleotidase activity as therapeutic one in first hour after irradiation. Another findings is that in early postnatal development, brain ecto-5'nucleotidase was resistant to irradiation damage.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Ionizing irradiation affect extracellular nucleotide hydrolysis in brain of rats in different stages of development: i 15-day-old rats

Ionizing radiation affects plasma membrane functions mediated through transmembrane proteins including enzymes. Plasma membrane surface-located enzyme chain of ecto-nucleotide triphospho diphosphohydrolases (NTPDases) are involved in termination of cell purinergic signalization by hydrolysing extracellular adenosine tri- and di-phosphate (ATP and ADP). In the present study, effects of low (50 cGy) and therapeutic (2 Gy) dose of ionizing γ-irradiation on NTPDase activity in early postnatal rat brain neuronal cells were studied. Both low- and therapeutic doses significantly decreased hydrolyze of extracellular ATP (by 11% and 30%) and ADP (18% and 46%) in postnatal rats. These findings indicate that gammaradiation inhibits the enzyme activity in dose-dependent manner. This decreasing NTPDase activity 24h after whole body irradiation may lead to neuronal cell function disturbance, even cell death.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Parkinson’s disease – state of the art

Parkinsonova bolest (PB) je kompleksno progresivno neurodegenerativno oboljenje sa nerazjašnjenom etiopatogenezom. Odlikuje je, između ostalog, narušena struktura i funkcija komponenti dopaminskog sistema u delu mozga u kome se nalaze centri za izvođenje voljnih pokreta, kogniciju i pamćenje, dok su na ćelijskom nivo karakteristične neuroinflamacija, narušavanje strukture i funkcija mnogih organela uključujući mitohondrije, lizozome ili transportne vezikule, poremećen redoks status, nepravilno savijanje proteina koje uslovljava njihovo neadekvatno funkcionisanje, stvaranje unutarćelijskih depozita različitih supstanci (molekula/jona). Obično se manifestuje kombinacijom niza motornih i nemotornih simptoma, uključujući tremor pri mirovanju, usporenost i osiromašenost pokreta (bradikinezija), ukočenost mišića (rigidnost) ruku, nogu i vrata, gubitak posturalnih refleksa, fleksibilan položaj tela, kao i konstipacija, urinarna disfunkcija, impotencija, poremećaji faza sna, prekomerna dnevna pospanost, nemogućnost gutanja pljuvačke, znojenje, mučnina, anksioznost, apatija, depresija, demencija. Dijagnostikovanje PB se vrši posredno na osnovu prisustva minimum dva motorna simptoma i adekvatan odgovor na antiparkinson terapiju, a sa sigurnošću se potvrđuje tek post-mortem analizama utvrđivanjem postojanja karakterističnih patohistoloških promena u različitim regionima mozga. Kao potencijalni uzročnici njenog nastanka i progresije izdvajaju se genski faktori, faktori spoljašnje sredine, kao i njihovo međusobno delovanje. Izazovi PB su ne samo nemogućnost ranog uspostavljanja dijagnoze, poteškoće u procenjivanju toka bolesti, identifikacija potencijalnih biomarkera i signalnih puteva koji su uključeni u patogenezu, njihova uloga u kliničkoj prezentaciji bolesti, već i terapija. Iako se ovo hronično oboljenje leči različitim lekovima (farmakoterapija), hirurškim zahvatima, i potpornim, komplementarnim i alternativnim terapijama, ni jedan od navedenih vidova terapije ne omogućava potpuno ozdravljenje već kontrolu simptoma radi što dužeg nezavisnog funkcionisanja obolelih.Parkinson’s disease (PD) is a complex progressive neurodegenerative disease with uncertain etiopathogenesis. Among others, it is characterized by impaired structure and function of components of the dopamine system in regions of the brain responsible for performing voluntary movements, cognition and memory; neuroinflammation; disruption of structure and function of various organelles including mitochondria, lysosomes or transport vesicles, disturbed redox status, misfolding of proteins, intracellular deposition of various substances (molecules/ions). Usually PD is manifested by a combination of several motor and non-motor symptoms, including resting tremor, slowness of movement and speed (bradykinesia), stiffness of arms, legs and neck muscles (rigidity), loss of postural reflexes, flexible body position, along with constipation, urinary dysfunction, impotence, sleep disorders, excessive daytime sleepiness, inability to swallow saliva, sweating, nausea, anxiety, apathy, depression, dementia. Diagnosing is performed indirectly based on the presence of at least two motor symptoms and an adequate response to antiparkinsonian therapy, while it can be confirmed with certainty only by post-mortem analysis according to the existence of characteristic pathohistological changes in different regions of the brain. In PD pathogenesis the relative contribution of genes, environmental/lifestyle factors, as well as their specific interactions has been recognized. The challenges of PD are not only the impossibility of early diagnosis, difficulties in assessing the course of the disease, the identification of potential biomarkers and signaling pathways involved in pathogenesis, their role in the clinical presentation of the disease, but also the therapy. Although the PD patients are treated with various drugs (pharmacotherapy), surgical interventions, and supportive, complementary and alternative therapies, none of the mentioned types of therapy provide the healing but they enable the control of the symptoms for the longest possible independent functioning of the patients

Neuroprotective progesterone potential

Poremećena moždana cirkulacija, koja je karakteristična za starenje i mnoga cerebrovaskularna i/ili neurodegenerativna oboljenja, povezuje se sa prooksidativnim i proapoptotskim promenama mnogobrojnih biomolekula, uključujući lipide, proteine i DNK, i narušavanjem strukture i funkcije ćelija prečeone moždane kore (PFC) i hipokampusa (HIPP). Do sada je testiran efekat brojnih jedinjenja da bi se ublažile posledice narušenog protoka krvi kroz moždano tkivo, ali adekvatna terapija još uvek nije dostupna. Ipak, kao jedan od mogućih terapeutika, izdvaja se steroidni hormon, progesteron (pregn-4-en-3,20-dion, P4), za kojeg je pokazano da ispoljava zaštitne efekte u mnogim životinjskim eksperimentalnim modelima kojima se oponašaju pojedini aspekti poremećaja strukture i funkcije moždanih ćelija primećeni kod starijih ljudi i obolelih od cerebrovaskularnih i/ili neurodegenerativnih bolesti. Stoga, fokus ovog rada je pružanje mogućnosti boljeg razumevanja molekulskih mehanizama delovanja P4 u mozgu u fiziološkom stanju, kao i terapijskog potencijala koji iskazuje u animalnim modelima cerebrovaskularnih i neurodegenerativnih bolesti, sa posebnim osvrtom na trajnu moždanu hipoperfuziju (MH) gde pokazuje regionalno-specifično dejstvo. Iako se P4, za sada, u humanoj populaciji pokazao kao neadekvatan terapeutik u lečenju patološkog stanja povezanog sa poremećenom moždanom cirkulacijom, dodatne kliničke studije bi obezbedile saznanja o efektu ovog potentnog neurosteroida kod obolelih od drugih cerebrovaskularnih i/ili neurodegenerativnih bolesti, dok bi u slučaju ohrabrujućih rezultata, P4 terapija mogla znatno olakšati kvalitet života obolelih.Disturbed cerebral circulation, characteristic for aging and many cerebrovascular and/or neurodegenerative diseases, is associated with prooxidative and proapoptotic changes of various biomolecules, including lipids, proteins and DNA, and with compromised cell structure and function in prefrontal cortex (PFC) and hippocampus (HIPP). Numerous compounds, until today, have been tested to alleviate the outcomes of impaired blood flow through brain tissue, but adequate therapy is not yet available. However, one of the possible therapeutics is singled out, the steroid hormone, progesterone (pregn-4-en-3,20-dione, P4), which has been shown to exert protective effects in many animal experimental models that mimic certain aspects of brain structural and functional changes observed in the elderly and those suffering from cerebrovascular and/or neurodegenerative diseases. Therefore, this paper is focused on providing a better understanding of physiological P4-mediated brain molecular mechanisms, as well as its therapeutic potential in animal models of cerebrovascular and neurodegenerative diseases with the emphasis on permanent cerebral hypoperfusion (CH) where the regional-specific response is observed. Although P4 is shown as inadequate for treating a pathological condition associated with disturbed cerebral circulation, additional clinical studies would provide insights into the potential therapeutic capacity of this potent neurosteroid in other cerebrovascular and/or neurodegenerative diseases and conditions. In the case of encouraging results, P4 therapy could significantly improve the quality of patients’ life

Ionizing irradiation affect extracellular nucleotide hydrolysis in brain of rats in different stages of development: ii 30-day-old rats

The effect of acute gamma irradiation (IR) on enzyme activity of rat brain Ecto-Nucleotide Diphosphohydrolase (E-NTPDase), in presence of adenosine triand diphophashates (ATP and ADP) and divalent cations (Ca2+ and Mg2+), has been investigated. The aim of research was to study the influence of low (50 cGy) and therapeutic (2Gy) doses of whole-body irradiation on rat brain E-NTPDase enzyme activity 24h after treatment in prepubertal and adult rats. Our results suggest that whole-body irradiation could induce modulation of neural activity in rat brain, especially in young rats.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Innovative and multidisciplinary approaches in detecting biological agents using contemporary technologies

International Scientific Conference “Archibald Reiss Days” Belgrade, 8-9 November 2023 : Conference Proceedings of International Significanc

Acute Toxicity Assessment of Orally Administered Microplastic Particles in Adult Male Wistar Rats

While the effects of chronic exposure to microplastic particles (MPs) are extensively studied, the outcomes of a single treatment have received relatively less attention. To investigate MPs’ potential acute toxicity, including their impact on general health status (victual consumption, sensorimotor deficits, and clinical toxicity signs) and serum biochemical parameters (markers of organ/tissue function and oxidative stress indicators), we administered thoroughly characterized MPs (1.4, 35, or 125 mg/kg), generated from polyethylene terephthalate (PET) bottles, to adult male Wistar rats via oral gavage. The MPs’ short-term effects were assessed with well-established tests and methods. The results point to the absence of sensorimotor deficits and clinical toxicity signs, while levels of markers of liver, heart, and kidney function were altered in all MP groups. Decreased victual consumption and increased levels of oxidative stress indicators were evident following treatment with the two higher MP doses. Presented data indicate that examined MPs are able to initiate the development of local changes in tissues and organs within a short time frame, potentially leading to their damage and dysfunction. This study may increase the awareness of the detrimental effects of plastic contamination, as even a single exposure to MPs may provoke adverse health outcomes

Titanium(IV) oxide nanoparticles surface-modified with salicylic and 5-aminosalicylic acid affect lipid and protein oxidation in the brain of Wistar rats

13th Neuronus 2024 Neuroscience Forum Krakow, 25-27 April 2024

Estradiol receptors mediate estradiol-induced inhibition of mitochondrial Ca2+ efflux in rat caudate nucleus and brain stem

Our earlier studies found that in vitro estradiol modulates mitochondrial Ca2+ transport in discrete brain regions. The present study examined the role of estradiol receptors (ERs) in estradiol-induced inhibition of Ca2+ efflux from synaptosomal mitochondria isolated from rat caudate nuclei and brain stems. Radioactively labeled CaCl2 (0.6-0.75 mu Ci (CaCl2)-Ca-45) was used for Ca2+ transport monitoring. The results revealed that in the presence of ER antagonist 7 alpha, 17 beta-[9[(4,4,5,5,5-pentafluoropentyl) sulfinyl] nonyl] estra-1,3,5( 10)-triene-3,17-diol (ICI 182,780) (1 mu mol/L), the inhibitory effect of estradiol on mitochondrial Ca2+ efflux was more than 60% decreased, suggesting the involvement of ER in this mode of estradiol neuromodulatory action. When particular contributions of ER alpha and ER beta were tested, it was found that ER beta agonist 2,3-bis(4-hydroxy phenyl)-propionitrile (10 nmol/L) inhibited Ca2+ efflux more than 20%, while the inhibition with ER alpha agonist 4,4', 4''-(4-propyl-[1H]-pyrazole-1,3,5-triyl) trisphenol (10 nmol/L) was about 10%, both compared to the control. Both agonists demonstrated attenuation of Ca2+ efflux decrease in the presence of mitochondrial Na+/Ca2+ exchanger antagonist 7-chloro-5-(2-chlorophenyl)-1,5-dihyhdro-4,1-benzothiazepin-2(3H)-one (10 mu mol/L), showing interference with the inhibitory action of that agent. Our results strongly indicate ERs as the mediators of estradiol-induced mitochondrial Ca2+ efflux inhibition in rat caudate nucleus and brain stem synaptosomes