Detrimental effects of tropisetron on permanent ischemic stroke in the rat

Background  

Recent in vitro evidence indicates that blockade of 5-hydroxytryptamine (5-HT) receptor 3 (5-HT₃) is able to confer protection in different models of neuronal injury. The purpose of the present study was to investigate the effect of tropisetron, a 5-HT₃ receptor antagonist, on infarct size and neurological score in a model of ischemic stroke induced by permanent middle cerebral artery occlusion (pMCAO) in the rat.     

Blockade of stress-induced increase of glutamate release in the rat prefrontal/frontal cortex by agomelatine involves synergy between melatonergic and 5-HT2C receptor-dependent pathways

Background

Agomelatine is a melatonergic receptor agonist and a 5HT_2C receptor antagonist that has shown antidepressant efficacy. In order to analyze separately the effect of the two receptorial components, rats were chronically treated with agomelatine, melatonin (endogenous melatonergic agonist), or S32006 (5-HT_2C antagonist), and then subjected to acute footshock-stress.

Results

Only chronic agomelatine, but not melatonin or S32006, completely prevented the stress-induced increase of glutamate release in the rat prefrontal/frontal cortex.

Conclusions

These results suggest a potential synergy between melatonergic and serotonergic pathways in the action of agomelatine.     

Detection of human and rodent 5-HT3B receptor subunits by anti-peptide polyclonal antibodies

Background  

The 5-HT₃ receptor is a member of a neurotransmitter-gated ion channel family which includes nicotinic acetylcholine, GABA_A, and glycine receptors. While antibodies specific for the 5-HT_3A receptor subunit are plentiful, and have revealed a wealth of structural and functional information, few antisera exist for the detection of 5-HT_3B receptor subunits. Here we describe the generation and characterisation of a rabbit polyclonal antiserum that specifically recognises 5-HT_3B receptor subunits     

Serotonin 5-HT2A and 5-HT6 receptors in the prefrontal cortex of Alzheimer and normal aging patients

Background  

It has been hypothesized that alterations of the serotonergic system contribute to neuropsychiatric symptoms in Alzheimer disease (AD). Cellular expressions of the two serotonergic receptors 5-HT_2A and 5-HT₆ have therefore been determined by immunohistochemistry in the prefrontal cortex of patients with AD (n=6) and normal age-matched controls (n = 7).     

Evidence for neuroprotective properties of human umbilical cord blood cells after neuronal hypoxia <Emphasis Type="Italic">in vitro</Emphasis>

Background  

One of the most promising options for treatment of stroke using adult stem cells are human umbilical cord blood (HUCB) cells that were already approved for therapeutic efficacy in vivo. However, complexity of animal models has thus far limited the understanding of beneficial cellular mechanisms. To address the influence of HUCB cells on neuronal tissue after stroke we established and employed a human in vitro model of neuronal hypoxia using fully differentiated vulnerable SH-SY5Y cells. These cells were incubated under an oxygen-reduced atmosphere (O₂< 1%) for 48 hours. Subsequently, HUCB mononuclear cells (MNC) were added to post-hypoxic neuronal cultures. These cultures were characterized regarding to the development of apoptosis and necrosis over three days. Based on this we investigated the therapeutic influence of HUCB MNC on the progression of apoptotic cell death. The impact of HUCB cells and hypoxia on secretion of neuroprotective and inflammatory cytokines, chemokines and expression of adhesion molecules was proved.     

Non-invasive evaluation of nigrostriatal neuropathology in a proteasome inhibitor rodent model of Parkinson's disease

Background  

Predominantly, magnetic resonance imaging (MRI) studies in animal models of Parkinson's disease (PD) have focused on alterations in T₂ water ¹H relaxation or ¹H MR spectroscopy (MRS), whilst potential morphological changes and their relationship to histological or behavioural outcomes have not been appropriately addressed. Therefore, in this study we have utilised MRI to scan in vivo brains from rodents bearing a nigrostriatal lesion induced by intranigral injection of the proteasome inhibitor lactacystin.     

Ankyrin repeat and SOCS box containing protein 4 (Asb-4) colocalizes with insulin receptor substrate 4 (IRS4) in the hypothalamic neurons and mediates IRS4 degradation

Background

Cigarette smoking enhances the risk of stroke. However, the underlying molecular mechanisms are largely unknown. The present study established an in vivo rat secondhand cigarette smoking (SHS) model and examined the hypothesis that SHS upregulates endothelin receptors with increased cerebrovascular contraction via the Raf/extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinases (MAPK) pathway.

Results

Rats were exposed to SHS for up to 8 weeks. The cerebral artery vasoconstriction was recorded by a sensitive myograph. The mRNA and protein expressions for endothelin receptors in cerebral arteries were studied by real-time PCR and Western blot. Compared to fresh air exposed rats, cerebral arteries from SHS rats exhibited stronger contractile responses (P < 0.05) mediated by endothelin type A (ET_A) receptors. The expressions of mRNA and protein for ET_A receptors in the cerebral arteries from SHS rats were higher (P < 0.05) than that in control. SHS did not affect endothelin type B (ET_B) receptor-mediated contractions, mRNA or protein levels. The results suggest that SHS upregulates ET_A, but not ET_B receptors in vivo. After SHS exposure, the mRNA levels of Raf-1 and ERK1/2, the protein expression of phosphorylated (p)-Raf-1 and p-ERK1/2 were increased (P < 0.05). Raf-1 inhibitor, GW5074 suppressed the enhanced ET_A receptor-mediated contraction, mRNA and protein levels induced by SHS. In addition, GW5074 inhibited the SHS-caused increased mRNA and phosphorylated protein levels of Raf-1 and ERK1/2, suggesting that SHS induces activation of the Raf/ERK/MAPK pathway.

Conclusions

SHS upregulates cerebrovascular ET_A receptors via the Raf/ERK/MAPK pathway, which provides novel understanding of mechanisms involved in SHS-associated stroke.     

Transient change in GABAA receptor subunit mRNA expression in Lurcher cerebellar nuclei during Purkinje cell degeneration

Background  

Lurcher mice suffer from a complete Purkinje cell (PC) loss in the first four postnatal weeks. Parallel to this degeneration, GABAergic synapses in the deep cerebellar nuclei (DCN), the major recipient of the inhibitory PC projection, increase synaptic conductance. Here, we further investigated this phenomenon, using real-time RT-PCR to assess GABA_A receptor subunit gene expression during PC degeneration.     

Effects of brain polarization on reaction times and pinch force in chronic stroke

Background  

Previous studies showed that anodal transcranial DC stimulation (tDCS) applied to the primary motor cortex of the affected hemisphere (M1_{affected hemisphere}) after subcortical stroke transiently improves performance of complex tasks that mimic activities of daily living (ADL). It is not known if relatively simpler motor tasks are similarly affected. Here we tested the effects of tDCS on pinch force (PF) and simple reaction time (RT) tasks in patients with chronic stroke in a double-blind cross-over Sham-controlled experimental design.     

EPR studies on the di-nitrogen centers with nonequivalent atoms in a reddish-brown plastically deformed diamond

Two new di-nitrogen centers, which were labeled M2 and M3, were found together with known W7 and N4 centers in an unusual reddish-brown natural diamond. The following magnetic hyperfine interaction parameters (expressed in MHz) were determined for the two nitrogen atoms:A ₁ ⁽¹⁾ =117.95(5),A ₁ ⁽²⁾ =A ₁ ⁽³⁾ =84.48(5),A ₂ ⁽¹⁾ =7.1(1),A ₂ ⁽²⁾ =A ₂ ⁽³⁾ =6.6(1) for M2 andA ₁ ⁽¹⁾ =121.55(5),A ₁ ⁽²⁾ =A ₁ ⁽³⁾ =85.90(5),A ₂ ⁽¹⁾ =6.0(1),A ₂ ⁽²⁾ =5.4(1),A ₂ ⁽³⁾ =5.1(1) for M3. Hyperfine interaction tensors for the nitrogen atom N₁ with a larger interaction have axial symmetry about the <111> direction, but those for the other nitrogen atom, N₂, appear to be small, almost isotropic. Probable models of the M2 and M3 centers are suggested and discussed.     

The hematopoietic factor GM-CSF (Granulocyte-macrophage colony-stimulating factor) promotes neuronal differentiation of adult neural stem cells in vitro

Background  

Granulocyte-macrophage colony stimulating factor (GM-CSF) is a hematopoietic growth factor involved in the generation of granulocytes, macrophages, and dendritic cells from hematopoietic progenitor cells. We have recently demonstrated that GM-CSF has anti-apoptotic functions on neurons, and is neuroprotective in animal stroke models.     

Automated quantitative gait analysis in animal models of movement disorders

Background  

Accurate and reproducible behavioral tests in animal models are of major importance in the development and evaluation of new therapies for central nervous system disease. In this study we investigated for the first time gait parameters of rat models for Parkinson's disease (PD), Huntington's disease (HD) and stroke using the Catwalk method, a novel automated gait analysis test. Static and dynamic gait parameters were measured in all animal models, and these data were compared to readouts of established behavioral tests, such as the cylinder test in the PD and stroke rats and the rotarod tests for the HD group.     

Modulatory effect of adenosine receptors on the ascending and descending neural reflex responses of rat ileum

Background

Adenosine is known to act as a neuromodulator by suppressing synaptic transmission in the central and peripheral nervous system. Both the release of adenosine within the small intestine and the presence of adenosine receptors on enteric neurons have been demonstrated. The aim of the present study was to characterize a possible involvement of adenosine receptors in the modulation of the myenteric reflex. The experiments were carried out on ileum segments 10 cm in length incubated in an single chambered organ bath, and the reflex response was initiated by electrical stimulation (ES).

Results

ES caused an ascending contraction and a descending relaxation followed by a contraction. All motility responses to ES were completely blocked by tetrodotoxin, indicating that they are mediated by neural mechanisms. Atropine blocked the contractile effects, whereas the descending relaxation was significantly increased. The A₁ receptor agonist N6-cyclopentyladenosine increased the ascending contraction, whereas the ascending contraction was reduced by the A₁ receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine. Activation of the A₁ receptor further reduced the descending relaxation and the latency of the peristaltic reflex. The A_2B receptor antagonist alloxazine increased ascending contraction, whereas descending relaxation remained unchanged. For A_2A and A₃ receptors, we found contradictory effects of the agonists and antagonists, thus there is no clear physiological role for these receptors at this time.

Conclusions

This study suggests that the myenteric ascending and descending reflex response of the rat small intestine is modulated by release of endogenous adenosine via A₁ receptors.     

Slow GABA<Subscript>A</Subscript>mediated synaptic transmission in rat visual cortex

Background  

Previous reports of inhibition in the neocortex suggest that inhibition is mediated predominantly through GABA_A receptors exhibiting fast kinetics. Within the hippocampus, it has been shown that GABA_A responses can take the form of either fast or slow response kinetics. Our findings indicate, for the first time, that the neocortex displays synaptic responses with slow GABA_A receptor mediated inhibitory postsynaptic currents (IPSCs). These IPSCs are kinetically and pharmacologically similar to responses found in the hippocampus, although the anatomical specificity of evoked responses is unique from hippocampus. Spontaneous slow GABA_A IPSCs were recorded from both pyramidal and inhibitory neurons in rat visual cortex.     

Dynamic changes in GABA<Subscript>A</Subscript>receptors on basal forebrain cholinergic neurons following sleep deprivation and recovery

Background  

The basal forebrain (BF) cholinergic neurons play an important role in cortical activation and arousal and are active in association with cortical activation of waking and inactive in association with cortical slow wave activity of sleep. In view of findings that GABA_A receptors (Rs) and inhibitory transmission undergo dynamic changes as a function of prior activity, we investigated whether the GABA_ARs on cholinergic cells might undergo such changes as a function of their prior activity during waking vs. sleep.     

Imaging longitudinal changes in articular cartilage and bone following doxycycline treatment in a rabbit anterior cruciate ligament transection model of osteoarthritis

Objective

The development of osteoarthritis following traumatic anterior cruciate ligament (ACL) injury is well established. However, few reliable indicators of early osteoarthritic changes have been established, which has limited the development of effective therapies. T_1ρ and T₂ mapping techniques have the ability to provide highly accurate and quantitative measurements of articular cartilage degeneration in vivo. Relating these cartilaginous changes to high-resolution bone-densitometric evaluations of the late-stage osteoarthritic bone is crucial in elucidating the mechanisms of development of traumatic osteoarthritis (OA) and potential therapies for early- or late-stage intervention.

Methods

Twelve rabbits were monitored with in vivo magnetic resonance imaging (MRI) scans following ACL transection surgery with a contralateral leg sham operation. Six of the rabbits were treated with oral doxycycline for the duration of the experiment. At 12 weeks, the excised knees from three animals from each group (n=6 overall) were subjected to micro-computed tomography (CT) analysis.

Results

Consistent with previous studies, initial elevations in T_1ρ and T₂ values in ACL-transected animals were observed with relative normalization towards values see in sham-operated legs over the 12-week study. This biphasic pattern could hold diagnostic potential to differentiate osteoarthritic cartilage by tracking the relative proportions of T_1ρ and T₂ values as they rise with inflammation then fall as collagen and proteoglycan loss leads to further dehydration. The addition of doxycycline resulted in inconclusive, yet potentially interesting, cartilaginous changes in several compartments of the rabbit legs. Micro-CT studies demonstrated decreased bone densitometrics in ACL-transected knees. Correlation studies suggest that the cartilaginous changes may be associated with some aspects of bony change and the development of OA.

Conclusion

We conclude that there are definite relationships between cartilaginous changes as seen on MRI and late-stage microstructural bony changes after traumatic ACL injury in rabbits. In addition, doxycycline may show promise in mitigating early-stage cartilage damage that may serve to lessen late-stage osteoarthritic changes. This study demonstrates the ability to track OA progression and therapeutic efficacy with imaging modalities in vivo.     

Resonant shielding of an inhomogeneous gyrotropic plasma slab

Conclusions The problem of the incidence of a plane TM electromagnetic wave on an isotropic, symmetric, resonance plasma slab (n=2, 4, 6, ...), discussed in [1], was solved by an iteration method in a recent paper [6]. The physical results found there are the same as those of [1]. Zhivulin and Makarov [6] then applied the iteration method to the analogous problem of a gyrotropic resonance plasma slab [7]. The analysis in these papers furnishes a clearer mathematical justification of the results of [1] and the present paper and thus of the method used there. The present method, which satisfies only a physical condition of rigor, is preferable to the mathematically more rigorous methods (in particular, the iteration method) because of its simplicity, its graphic nature, and its clear physical meaning. It also answers many questions which cannot be answered in the more rigorous approach because of the serious difficulties which arise (and which have not yet been overcome).N. G. Denisov has called our attention to the fact that complete shielding was actually found previously by Rytov and Yudkevich [8], who treated the problem of the incidence of a plane TE electromagnetic wave on a slab with a dielectric constant (x)=₁ – A₁/(a – x)² for x<0. (x)=₂ – A₂/(b + x)² for x>0, and ₁ – A₁/(a² = ₂ – A₂/b² in the plane x=0. In the limita0, b0, they found results corresponding to a slab with a dielectric constant having a first-order pole; it is in this case that complete shielding is achieved. This method for obtaining the corresponding results is analogous to the method used in [1] and the present paper. We also note that the distribution of the effective dielectric constant (6) in the immediate vicinity of the pole—where the contribution of the last term. (1–u)x², can be neglected—is the same as the distribution adopted in [8] if we seta-b-0, ₁ = ₂, A₁=A₂=u.Scientific-Research Institute of Radiophysics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 19, No. 8, pp. 1130–1141, August, 1976.     

Fiber-coupled Al2O3:C radioluminescence dosimetry for total body irradiations

In vivo dosimetry can be important and relevant in radiotherapy, especially when commissioning new treatment techniques at hospitals. This study investigates the potential use of fiber-coupled radioluminescence (RL) dosimetry based on Al₂O₃:C or organic plastic scintillators for this purpose in the context of Total Body Irradiations (TBIs) where patients are treated with large fields of 6 or 18 MV photons at an extended source-to-surface distance (SSD). The study shows that Al₂O₃:C dosimetry using the saturated-RL protocol may be suitable for real-time in vivo dosimetry during TBI treatments from the perspective of the good agreement with alanine dosimetry and other critical phantom tests, including the ability to cope with the large stem signal experienced during TBI treatments at extended SSD. In contrast, the chromatic stem removal technique often used for organic plastic scintillators did not work well in large fields with the tested calibration procedure and instrumentation. An apparent dose-rate effect discussed in a previous study of the RL properties of Al₂O₃:C (Andersen et al., 2011) was found to have resulted from an overlooked dead time problem in the counting system, and this potential caveat can therefore be removed from the list of potential problems associated with fiber-coupled Al₂O₃:C dosimetry using the saturated-RL protocol. This further has implications for TBI dosimetry using the RL Al₂O₃:C system due to large dose-rate differences between calibrations at the iso-center and in vivo measurements at extended source-to-surface distances.     

Changes in the 5-HT2A receptor system in the pre-mammillary hypothalamus of the ewe are related to regulation of LH pulsatile secretion by an endogenous circannual rhythm

Background  

We wanted to determine if changes in the expression of serotonin 2A receptor (5HT2_A receptor) gene in the premammillary hypothalamus are associated with changes in reproductive neuroendocrine status. Thus, we compared 2 groups of ovariectomized-estradiol-treated ewes that expressed high vs low LH pulsatility in two different paradigms (2 groups per paradigm): (a) refractoriness (low LH secretion) or not (high LH secretion) to short days in pineal-intact Ile-de-France ewes (RSD) and (b) endogenous circannual rhythm (ECR) in free-running pinealectomized Suffolk ewes in the active or inactive stage of their reproductive rhythm.     

Role of ionotropic GABA,glutamate and glycine receptors in the tonic and reflex control of cardiac vagal outflow in the rat

Background  

Cardiac vagal preganglionic neurons (CVPN) are responsible for the tonic, reflex and respiratory modulation of heart rate (HR). Although CVPN receive GABAergic and glutamatergic inputs, likely involved in respiratory and reflex modulation of HR respectively, little else is known regarding the functions controlled by ionotropic inputs. Activation of g-protein coupled receptors (GPCR) alters these inputs, but the functional consequence is largely unknown. The present study aimed to delineate how ionotropic GABAergic, glycinergic and glutamatergic inputs contribute to the tonic and reflex control of HR and in particular determine which receptor subtypes were involved. Furthermore, we wished to establish how activation of the 5-HT_1A GPCR affects tonic and reflex control of HR and what ionotropic interactions this might involve.