yaghoub fathollahi

Iron is an essential element that works as a cofactor in mitochondrial respiration, neurotransmitter biosynthesis, and myelination enzymes. Several pieces of evidence reveal that iron accumulates in demyelinating lesions in patients with multiple sclerosis (MS), and its intracellular homeostasis is disrupted, which exacerbates inflammation and demyelination.

We reanalyzed a microarray human MS dataset from GEO DataSests, under accession number GSE108000. We examined differentially expressed genes involved in iron metabolism between different types of MS lesions and peri-lesional normal-appearing white matter (PL-NAWM). We used GEO2R for differential expression analysis and created volcano plots, Venn diagrams, and pie charts for data visualization using RStudio software.

We identified 58 genes involved in iron metabolism within the dataset. The expression of key iron-regulating genes, responsible for iron uptake, storage, and export, including CYBRD1, STEAP3, SLC39A14, FTL, FTH1, and CP were significantly changed. We also indicated significant alterations in the iron regulatory pathways in MS lesions and the PL-NAWM. The most prominent alterations were related to the iron uptake pathway, which showed enhanced activity.

Significant changes in iron regulatory gene expressions across MS lesions and the PL-NAWM may lead to dysregulation in iron homeostasis. This imbalance likely contributes to neurodegenerative processes associated with MS. The modifications in the PL-NAWM can be regarded as early-disease indicators. Recognizing these molecular changes provides valuable insights for facilitating timely MS diagnosis and developing targeted therapeutic strategies.

Immune checkpoints are molecules that regulators  the immune system. However, some tumor cells can express the ligands of immune checkpoints to escape from antitumor immune responses. Some agents, such as antibodies, can inhibit these checkpoints that prevent the immune system from targeting and killing cancer cells. The aim of this study was to express a novel bispecific diabody in periplasmic space of E.coli for simultaneous targeting of two immune checkpoints, cytotoxic T‑lymphocyte‑associated protein 4 (CTLA‑4) and programmed death- ligand 1 (PD‑L1). The bispecific diabody was constructed based on the variable regions gene of anti PD-L1 and anti CTLA‑4 antibodies. The optimum codon for expression in E. coli was chemically synthesized and subcloned in pET21 expression plasmid. After transformation, the effect of cultivation conditions on periplasmic expression of the protein in E. coli BL21(DE3) was evaluated. Then, the bispecific diabody was purified . Expression of diabody with a molecular weight of 55 kDa was verified by Sodium dodecyl sulfate‑polyacrylamide gel electrophoresis and western blotting analysis. The best condition for soluble periplasmic expression was obtained to be incubation with 0.5 mM isopropyl β‑D‑1‑thiogalactopyranoside at 23°C. The protein was successfully purified using affinity chromatography with a final yield of 0.4 mg/L. The affinity of the purified protein interaction were checked by ELISA. Recombinant Diabody protein was cloned, expressed, and purified in a bacterial system and Diabody Interaction with PDL-1 receptor conformed by Cell-Elisa.

Deep brain stimulation (DBS) stands as an alternative treatment for drug-resistant temporal lobe epilepsies. In this study, we investigated the effects of both low- and high-frequency stimulation (LFS and HFS) of the olfactory bulb on locomotor activity and preferences for spending time in the central or border regions. Rats underwent a kindling procedure involving semi-rapid electrical stimulation (6 stimulations per day) of the hippocampal CA1 region. Fully kindled animals received LFS (1 Hz) or HFS (130 Hz) at four time points: 5 min, 6 h, 24 h, and 30 h after the last kindling stimulation. Subsequently, rats were placed in the open field chamber and allowed free, uninterrupted movement within the respective quadrant of the maze for a single 10-minute period. During this time, tracking software recorded movement, and locomotor activity as well as preferences for spending time in the central or border regions were evaluated. Overall, applying DBS in the olfactory bulb at both low and high frequencies decreased exploration time in the center and increased exploration time in the border for the rats. Furthermore, a higher intensity of HFS was more effective than a lower intensity of HFS in reducing anxiety or altering locomotor behavior. According to the results of the present study it may be suggested that applying DBS affects some aspects of the animals’ activity and therefore, the activity monitoring tests have to be done following DBS application.

Alzheimerchr('39')s disease is the most common cause of dementia in middle age and aging. It is the third leading cause of death among the elderly. Alzheimerchr('39')s disease is a neurodegenerative disorder, characterized by attention deficits, memory and learning impairment. Many researches try to find new alternative treatment options for Alzheimerchr('39')s disease. Deep brain stimulation (DBS) is one of the new therapies for treating this disease. Early studies have shown that applying DBS in the hippocampus, meynert nucleus, fornix, and entorhinal cortex of patients as well as experimental Alzheimer-like models in animals can improve learning abnormalities and increase the volume of the hippocampus. The mechanisms responsible for this effect are still unknown, but maybe DBS effect through changes in neurotransmitters and neuromodulators release, thereby regulates the neuronal activities. In this article, we first review the common drug treatments for Alzheimerchr('39')s disease and their complications, and then review the effect of DBS on the Alzheimerchr('39')s patient and the animal model of Alzheimerchr('39')s, and finally discuss the possible mechanisms involved in these therapeutic effects and changes in neurotransmitters.

Synaptic plasticity has been suggested as the primary physiological mechanism underlying memory formation. Many experimental approaches have been used to investigate whether the mechanisms underlying Long-Term Potentiation (LTP) are activated during learning. Nevertheless, little evidence states that hippocampal-dependent learning triggers synaptic plasticity. In this study, we investigated if learning and memory in the Barnes maze test are accompanied by the occurrence of LTP in Schaffer collateral to CA1 synapses in freely moving rats.

The rats were implanted with a recording electrode in stratum radiatum and stimulating electrodes in Schaffer collaterals of the CA1 region in the dorsal hippocampus of the right hemisphere. Following the recovery period of at least 10 days, field potentials were recorded in freely moving animals before and after training them in Barnes maze as a hippocampal-dependent spatial learning and memory test. The slope of extracellular field Excitatory Postsynaptic Potentials (fEPSPs) was measured before and after the Barnes maze test.

The results showed that the fEPSP slope did not change after learning and memory in the Barnes maze test, and this spatial learning did not result in a change in synaptic potentiation in the CA1 region of the hippocampus.

Spatial learning and memory in the Barnes maze test are not accompanied by LTP induction in Schaffer collateral-CA1 synapses.

Low-frequency stimulation (LFS) exerts suppressive effects in kindled animals. It is believed that overstimulated glutamatergic and decreased GABAergic transmission have long been associated with seizure activity. In this study, we investigated the effect of electrical LFS on different parameters of spontaneous excitatory and inhibitory post-synaptic currents (sEPSCs and sIPSCs) in hippocampal CA1 pyramidal cells in kindled animals.
In this experimental study, rats were kindled by electrical stimulation of the hippocampal CA1 area in a semi-rapid manner (12 stimulations/day). The animals were considered fully kindled when they showed stage 5 seizures on three consecutive days. One group of animals received LFS 4 times at 30 seconds, 6 hours, 18 and 24 hours following the last kindling stimulation. Each LFS consisted of 4 packages at 5 minutes intervals. Each package of LFS consisted of 200 pulses at 1 Hz and each monophasic square wave pulse duration was 0.1 millisecond. At 2-3 hours post-LFS, acute hippocampal slices were prepared and a whole cell patch clamp recording was performed in all animals to measure the different parameters of sEPSCs and sIPSCs.
In kindled animals, the inter-event interval (as an index of occurrence) of sEPSCs decreased, whereas sIPSC increased. In addition, the decay time constant of sIPSCs as an index of the duration of its activity decreased compared to the control group. There was no significant difference in other parameters between the kindled and control groups. Application of LFS in kindled animals prevented the observed changes. There was no significant difference between the measured parameters in kindledⱔ and control groups.
LFS application may prevent seizure-induced increase in the occurrence of sEPSCs and seizure-induced decrease in occurrence and activity duration of sIPSCs.

The rostral ventromedial medulla (RVM) acts a key role in the descending inhibitory pain modulation. Neuropeptide orexin-A (ORXA) is confined to thousands of neurons in the lateral hypothalamus (LH). While RVM gets the orexinergic projections, the orexin receptors are also expressed in this structure. The aim of this study was to specify the cellular effects of ORXA on RVM neurons in vitro by using the whole cell patch-clamp recording. RVM neurons were classified into three types based on their electrophysiological characteristics. Type 1 neurons exhibited an irregular spontaneous activity which was interrupted by periods of pause in 25% of recorded neurons. Type 2 neurons did not show any spontaneous baseline activity (53.8% of recorded neurons). Type 3 neurons fired repetitively without interruption (51.2% of recorded neurons). ORXA had either inhibitory or excitatory effects on 53.8% (7/13) of type 1 neurons. ORXA excited 46.4% (13/28) of type 2 neurons and 27.3% (3/11) of type 3 neurons. The excitatory effect of ORXA observed in type 2 neurons was suppressed by an orexin 1 receptor (OXR1) antagonist, SB-334867. Briefly, we hypothesized that the ORXA mediated excitation and/or inhibition in RVM neurons might work as a mechanism to modulate pain processing by orexinergic neurons.

Exposure to morphine decreases neurogenesis in the hippocampus. Recent studies have shown that voluntary running decreases the severity of anxiety behaviors and cognitive deficits, and increased synaptic plasticity in morphine-dependent rats.

This study aimed to investigate whether the morphine dependence-induced attenuation of hippocampal neuron number in rats would be reversed by voluntary running through a brain-derived neurotrophic factor (BDNF)-mediated mechanism.

The rats were received injections of 10 mg/kg of morphine twice a day over ten days of voluntary running. A specific antagonist of BDNF action (TrkB-IgG) was used to block the hippocampal BDNF action during the study period; cytochrome C (Cyt C) was used as the control drug.

We found that chronic exposure to morphine had decreased the number of dentate gyrus neurons in sedentary rats receiving Cyt C or IgG in comparison to the control rats (P < 0.05). Moreover, exercise groups receiving saline or morphine showed an increase in the number of neurons following ten days running; blocking the BDNF action with TrkB-IgG fully inhibited this effect (both, P = 0.0001).

This study demonstrates that that voluntary exercise can ameliorate the attenuation of hippocampal neuron number induced by morphine dependence through a BDNF-mediated mechanism. Thus, physical activity might have a potential role in ameliorating chronic morphine-induced neuronal changes in the hippocampus.

Alzheimer’s disease (AD) has been suggested to be a form of neuroplasticity failure. In addition to long term maladaptive changes in synaptic function, short term synaptic plasticity that has a role in information processing can be affected in AD that was investigated in this study. Field excitatory post synaptic potential (fEPSP) from Stratum radiatum of CA1 neurons were recorded following Schaffer collateral stimulation in a rat model of Alzheimer’s disease (AD). 1 µl of Aβ 1-42 (5µg/µl) and 1 µl of ibotenic acid (5µg/µl) were injected in dorsal hippocampus of male rats for AD induction. For examining the short-term synaptic plasticity, paired pulse stimulations with inter pulse interval (IPI) of 20, 80, and 200 ms were applied and paired pulse index (PPI) was calculated. Results showed that although AD induction decreased basal synaptic responses especially at high stimulus intensity, this change was not significant (ANOVA; P>0.05). Also there were no significant changes in PPI of AD rats at different IPIs including 20 ms (%40.4±4.68, n=5), 80 ms (%129.8±4.1, n=5), and 200 ms (%129±6.8, n=5) in comparison with control ones (%75.2±5.08, %138±7.56, %108.4±2.09 respectively, n=5, P>0.05, unpaired t-test). Such results indicate that hippocampal Aβ treatment does not lead to impairment of basal synaptic response and short term synaptic plasticity.

It is well known that intracerebroventricular (ICV) and supraspinal injections of orexin-A elicit analgesia, but the mechanism(s) of action remains unidentified. This study aims to characterize the effect of orexin-A on rostral ventromedial medulla (RVM) neurons which are involved in the descending nociception modulating pathway. In this experimental study, we injected orexin-A or vehicle directly into rats’ ICV while the tail flick (TF) latencies were measured and the on- and off-cell firing activities were monitored for more than 60 minutes. In response to noxious stimuli on the tail, we observed increased firing rate of on-cells and a decreased association with the firing rate of off-cells and in neutral cells the firing rate was unchanged just prior to tail flicking. ICV injection of orexin-A decreased the spontaneous firing rate of on-cells (the type of RVM neurons believed to have facilitatory action on nociception). Furthermore, orexin-A increased firing rate of off-cells (the type of RVM neurons believed to have an inhibitory action on nociception). Orexin-A reduced the TF-related responses of on-cells and TF-related pause duration of off-cells. These results have shown that the analgesic effect produced by orexin-A may be induced by brainstem neurons. It is suggested that the orexinergic system from the hypothalamus to the RVM may have a potential role in modulation of nociceptive transmission.

The prostaglandin E2 (PGE2), a cyclooxygenase (COX) product, play critical roles in the synaptic plasticity. Therefore, long term use of COX inhibitors may impair the synaptic plasticity. Considering the wide clinical administration of aspirin and its unknown effects on information processing in the brain, the effect of aspirin and sodium salicylate on the short term synaptic plasticity was investigated.

Field excitatory post synaptic potential (fEPSP) from stratum radiatum of CA1 neurons were recorded following Schaffer collateral stimulation in rats receiving aspirin in drinking water (2 mg/ml) for 6 weeks or sodium salicylate (six injection of 300 mg/kg, IP, twice daily) for 3 days. In order to examine the short-term synaptic plasticity, paired pulse stimulations with inter pulse intervals (IPI) of 20, 80, and 200 ms were applied and paired pulse index (PPI) was calculated.

The data showed that both sodium salicylate and aspirin decreased basal synaptic responses, although this change was significant in the sodium salicylate group, but not in aspirin treated rats (ANOVA; P<0.001). Sodium salicylate significantly increased PPI at 20 ms IPI (%90.7±1.6, n=5Vs. control: %76.1±1.5, n=5). Also significant increase in PPI was observed in aspirin treated rats (%125.9±6.6, n=5) at 20 ms IPI compared to control ones (%76.3±2.4, n=5, P<0.05, unpaired t-test).

In summary, our study suggests that aspirin and sodium salicylate may affect synaptic transmission and short term synaptic plasticity in the rat hippocampus.

A close link between spreading depression (SD) and several neurological diseases such as epilepsy could be demonstrated in many experimental studies. Epilepsy is among the most common brain disorders. Despite a large number of investigations, its mechanisms have not been yet well elucidated. Hippocampus is one of the important structures involved in seizures. The aim of this study is to get an insight into the patho-physiological processes induced by SD that lead to the generation of epileptiform field potentials. The horizontal amygdala-hippocampus-neocortex slices of rat brain in which SD was induced by KCl application in each brain structure were used. Following GABAA receptor antagonist bicuculline superfusion (1.25 μmol/L, for 45 min), SD induced epileptic activity in all tested slices was monitored. The induction of SD in the hippocampus resulted in interictal and ictal epileptiform field potentials and intracellular paroxysmal depolarization shifts (PDS). After SD, RMP slightly depolarized and the threshold of AP decreased, while the frequency of AP significantly increased. Amplitude of depolarization and also amplitude of discharges were also significantly increased. ISI significantly decreased and the most of neurons shifted from FA to SA indicating an enhanced excitability. SD may cause pathological changes in brain structures such as increased excitation and/or decreased inhibition. Propagation of SD over epileptogenic areas may trigger seizure attacks in some patients and our findings provide evidence on the role of SD in temporal lobe epilepsy.

Addiction is a chronic disorder that requires long-term drug treatments. However، the most drug treatments programs have limited success. The aim of the present study was to investigate the effects of voluntary exercise on naloxone-precipitated morphine withdrawal signs in rats.

All rats were individually housed in cages with a free access to a running wheel and received subcutaneous injection of saline or morphine (10 mg/kg) twice per day at 12 hr intervals for 10 days. Non-runner groups were confined to the similar cages with no access to the wheels، but treated by morphine or saline. Morphine dependent intensity was examined by acute morphine withdrawal and naloxone injection (2 mg/kg، IP) according to a modified version of the Gellert–Holtzman scale.

The results showed that there was no significant differences between control and morphine treated groups in running rates for a period of 10 days، indicating no effect of morphine on running activity. Withdrawal signs including abdominal contractions، wet dog shakes، weight loss (24h) and overall Gellert–Holtzman score were significantly lower in the exercising morphine treated rats as compared with non-exercising control rats (P= 0. 0001).

Our findings indicated that the physical activity diminishes severity of dependency on morphine. Thus، it could be a potential natural reward method for substituting with the others of care methods.

To assess the effect of penetration depth of the surface tripolar electrical stimulation, Tripolar TENS was applied with different intensities (equal to sensory threshold (ST), 1.25 ST, 1.5 ST) on vertebral column of twenty healthy and three hemiplegic subjects. The cathode of TENS was laid on the T11 vertebra and anodes were put 3cm apart from cathode, longitudinally and in the anode-cathode-anode arrangement. Before, after and 10 min after TENS the recruitment curve of soleus and gastrocnemius H-reflex and M wave were recorded. Experiments were done in four separate sessions. One of them was control session and the TENS apparatus was off in it. In each of the test sessions, TENS was applied with one of the intensities. The results showed that the 1.5 ST TENS have a complex facilitatory-inhibitory effect on recruitment curve of soleus H-reflex in the way that slow motoneurons were inhibited and fast motoneurons were facilitated. So the positive slope of curve was increased and the intensity needed to evoke Hmax was decreased. Amplitude of Hmax and threshold of the curve were slightly decreased. Gastrocnemius was facilitated after 1.5 ST TENS. The threshold of the H-reflex curve and needed intensity to evoke Hmax were decreased, while peak to peak amplitude of Hmax was increased. After ST TENS, soleus was facilitated and gastrocnemius had little change. It seems that 1.5 ST TENS facilitate Ia, Ib, fast motoneurons and renshaw cells via stimulating the dorsal column of the cord and renshaw inhibit slow motoneurons, so a complex of facilitation and inhibition appears in soleus motoneurons. In the case of gastrocnemius which the renshaw cells had not strong effect, H-reflex curve was facilitated. In ST TENS which only the skin afferents were stimulated the renshaw cells were inhibited by skin afferents and H-reflex was facilitated, But because the gastrocnemius motoneurons are slightly under control of renshaw and skin afferents synapses with motoneurons are not engaged in reflex loop, facilitation of skin afferents synapses after TENS application had no effect on the H-reflex parameters of gastrocnemius.

Chronic morphine exposure can cause addiction and affect synaptic plasticity, but the underlying neural mechanisms of this phenomenon remain unknown. Herein we used electrophysiologic approaches in hippocampal CA1 area to examine the effect of chronic morphine administration on short-term plasticity. Experiments were carried out on hippocampal slices taken from either control animals or animals made dependent via oral chronic morphine administration. Population spikes (PSs) were recorded from stratum pyramidale of CA1 following stimulation the Schaffer collateral afferents. For examining the short-term synaptic plasticity, paired pulse stimulations with inter pulse interval (IPI) of 10, 20, 80, and 200 ms were applied and paired pulse index (PPI) was calculated. Chronic morphine exposure had no effect on the baseline response. A significant increase in PPI was observed in dependent slices at 80 ms IPI as compared to the control ones. There was no significant difference in baseline response between control and dependent slices when we used long term morphine, naloxone, and both. However, long term morphine administration caused significant difference in PPI at IPI of 20 ms. This effect was eliminated in the presence of naloxone. These findings suggest that morphine dependence could affect short-term plasticity in hippocampal CA1 area and increase the hippocampus network excitability.

Orexin-A and B (Hypocretin 1 and 2) are neuropeptides that are mostly expressed in the posterior and lateral hypothalamus (LH). Intracisternal (ICV) and intratechal (IT) injections of orexin-A (hypocretin-1) have been shown to elicit analgesic responses in formalin test. However, the locations of central sites that may mediate these effects have not been clearly elucidated. Orexin-containing fibers are projected to periaqueductal gray matter (PAG), which is involved in pain modulation. Behavioral study was done on male Sprague Dawley rats (200-300 g) in formalin induced nociceptive behaviour. Intra-PAG microinjection of orexin-A produced a dose-dependent inhibition of formalin-evoked behaviour in interphase and phase 2, but not in phase 1, indicating an antinociceptive role of exogenous orexin-A in the PAG. Analgesic effect of orexin-A was less than and specific to inter- and late phase of formalin test, when compared with that of morphine (5 μg/0.5μl) after intra-PAG administration. The obtained results suggest that orexin-A plays an anti-nociceptive role in PAG, on the interphase and late phase of formalin test in rats. So it is possible that orexin-A might be involved in the mechanisms of inter- and last phases of formalin induced behaviours.