Alternative splicing is an important mechanism for expanding proteome diversity from a limited number of genes, especially in higher vertebrates. Brain-specific splicing factors play an important role in establishing specific patterns of alternative splicing in the brain and thereby contribute to its complex architecture and function. Nova proteins are splicing factors that are expressed specifically in the central nervous system, where they regulate a large number of pre-mRNAs encoding synaptic proteins that are important for the balance of neuronal excitation and inhibition. Since this balance is interrupted in epileptic seizures, we explored whether LiCl/pilocarpine- or kainate-induced epileptic seizures would induce changes in the levels of Nova mRNAs in the rat brain. We found that the muscarinic agonist, pilocarpine, but not the glutamatergic agonist, kainate, induced a significant downregulation of Nova2 mRNA and upregulation of all three Nova1 mRNA isoforms in the striatum. Treatment with the muscarinic antagonist, scopolamine, at the onset of pilocarpine-induced seizures inhibited the seizures and the changes in Nova mRNA levels. Therefore it seems likely that pilocarpine stimulation of muscarinic acetylcholine receptors was a prerequisite for the observed changes, while the contribution of other striatal neurotransmitter systems activated by seizures could not be excluded.We propose that the LiCl/pilocarpine seizure model could serve as a valuable tool for studying mechanisms of Nova-regulated alternative splicing in rat striatum.
COBISS.SI-ID: 27181785
Synaptotagmin-IV (Syt-IV) may function as a regulator of Ca2+-dependent synaptic transmission. In the hemi-parkinsonian rats with unilateral lesions of dopaminergic nigrostriatal neurons Syt-IV and substance-P (SP) mRNAs could be upregulated within the dopaminergically hypersensitive striatum of the lesioned brain hemisphere via the stimulation of striatal dopamine D1 (D1-R), but not D2 receptors. The hypersensitive D1-R-mediated transmission may be the culprit for the undesired expression of levodopa-induced dyskinesia, implying the involvement of Syt-IV and SP in the process. First, striatal cellular phenotypes expressing Syt-IV were determined. It was found to be expressed in all striatal neurons and a small population of astrocytes. Then it was examined, if the D1-R-mediated upregulation of Syt-IV mRNA may result in the upregulation of the translated protein. It was found that, after acute stimulation with a selective D1 agonist, (±)-6-chloro-7,8-dihydroxy-3-allyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrobromide (SKF-82958), Syt-IV was elevated within the SP-expressing striatal neurons of the lesioned side. This was followed by the upregulation of Syt-IV, but not of its mRNA, within the ipsilateral target nuclei of the direct-pathway medium spiny neurons, indicating axonal transport of de novo synthesized protein to their SP-positive synaptic terminals. However, despite the striatal upregulation of SP and Syt-IV following a similar time-course, their subcellular co-localization within the axonal terminals was not found. It was therefore suggested that Syt-IV may regulate the hypersensitive striatal synaptic transmission, although via a SP-independent mechanism.
COBISS.SI-ID: 32475353
Previous studies in rat models of neurodegenerative disorders have shown disregulation of striatal synaptotagmin7 mRNA. Here we explored the expression of synaptotagmin7 mRNA in the brains of rats with seizures triggered by the glutamatergic agonist kainate (10 mg/kg) or by the muscarinic agonist pilocarpine (30 mg/kg) in LiCl (3 mEq/kg) pre-treated (24 h) rats, in a time-course experiment (30 min-1 day). After kainate-induced seizures, synaptotagmin7 mRNA levels were transiently and uniformly increased throughout the dorsal and ventral striatum (accumbens) at 8 and 12 h, but not at 24 h, followed at 24 h by somewhat variable upregulation within different parts of the cerebral cortex, amigdala and thalamic nuclei, the hippocampus and the lateral septum. By contrast, after LiCl/pilocarpine-induced seizures, there was a more prolonged increase of striatal Synaptotagmin7 mRNA levels (at 8, 12 and 24 h), but only in the ventromedial striatum, while in some other of the aforementioned brain regions there was a decline to below the basal levels. After systemic post-treatment with muscarinic antagonist scopolamine in a dose of 2 mg/kg the seizures were either extinguished or attenuated. In scopolamine post-treated animals with extinguished seizures the striatal synaptotagmin7 mRNA levels (at 12 h after the onset of seizures) were not different from the levels in control animals without seizures, while in rats with attenuated seizures, the upregulation closely resembled kainate seizures-like pattern of striatal upregulation. In the dose of 1 mg/kg, scopolamine did not significantly affect the progression of pilocarpine-induced seizures or pilocarpine seizures-like pattern of striatal upregulation of synaptotagmin7 mRNA. In control experiments, equivalent doses of scopolamine per se did not affect the expression of synaptotagmin7 mRNA. We conclude that here described differential time course and pattern of synaptotagmin7 mRNA expression imply regional differences of pathophysiological brain activation and plasticity in these two models of seizures.
COBISS.SI-ID: 2564687
The aim of the work was to develop the chamber to be used in biomechanical, electrochemical and electrophysiological measurements in functional segments of peripheral nerves, when electrical stimulating pulses are selectively applied to preselected locations along the nerve and neural responses are measured. The main part of the chamber is the silicone multi-electrode spiral cuff system (cuff). It includes a spirally rolled matrix of ninety-nine platinum electrodes, arranged in eleven longitudinal spiral configurations of nine electrodes for establishing electrical contact with specific sites on theperipheral nerve. The chamber is constructed to enable simulation of various mechanical actions which could occur when the spiral cuff is installedon the nerve. For this purpose the chamber is equipped with sensors for measurement of stretching forces, spiral cuff diameter/radial pressure andstretching elongation. Nevertheless, the chamber is equipped also with a 3Dmicro-manipulator for precise positioning of various stimulating or recording microelectrodes. To perform electrochemical measurements using the method of cyclic voltammetry, the chamber is instrumented also with a Ag/AgCl reference electrode. To maintain appropriate thermal conditions, the chamber body was machined out from Plexiglas using a CNC milling machine and is instrumented with a water bath circulator and with a precision temperature probe for precise temperature regulation. A functionality of both, the developed experimental chamber and a single-part cuff was tested on the isolated and functional segment of the left vagus nerve of a pig at simulated physiological conditions.
COBISS.SI-ID: 30144985
Deposition of aggregates of hyperphosphorylated tau protein is a hallmark of tauopathies like Alzheimer and many other neurodegenerative diseases. A sensitive and selective method of in vivo detection of tau-aggregate presence and distribution could provide the means of an early diagnosis of tau-associated diseases. Furthermore, the use of selective molecular probes that enable histochemical differentiation of protein aggregates post-mortem would be advantageous for the insight into the properties of tau protein aggregates. We chose to design new molecular probes based on the structure of 2-(1-(6-((2-[18F]fluoroethyl)(methyl)amino)-2-naphthyl)ethylidene)malononitrile to investigate their likelihood of fitting into VQIVYK tau protein binding channel model. In a modular approach, using cross-coupling reactions, we synthesized a series of candidates, radiolabeled them with fluorine-18 radioisotope, and determined their physicochemical and in vitro binding properties. Herein we report the synthesis of a series of molecular probes capable of detection of tau protein deposits in vitro.
COBISS.SI-ID: 1537632707
This article reviews an improved methodology and technology for crafting a multi-electrode spiral cuff for the selective activation of nerve fibres in particular superficial regions of a peripheral nerve. The analysis, structural and mechanical properties of the spot welds used for the interconnections between the stimulating electrodes and stainless-steel lead wires are presented. The cuff consisted of 33 platinum electrodes embedded within a self-curling 17-mm-long silicone spiral sheet with a nominal internal diameter of 2.5 mm. The weld was analyzed using scanning electron microscopy and nanohardness tests, while the interconnection was investigated using destructive load tests. The functionality of the cuff was tested in an isolated porcine vagus nerve. The results of the scanning electron microscopy show good alloying and none of the typical welding defects that occur between the wire and the platinum foil. The results of the destructive load tests show that the breaking loads were between 3.22 and 5 N. The results of the nanohardness testing show that the hardness of the weld was different for the particular sites on the weld sample. Finally, the results of the functional testing show that for different stimulation intensities both the compound action potential deflection and the shape are modulated.
COBISS.SI-ID: 33600985
Purpose Aerobic training accelerates Heart Rate Recovery after exercise in healthy subjects and in patients with coronary disease. As shown by pharmacological autonomic blockade, HRR early after exercise is dependent primarily on parasympathetic reactivation. Thus, accelerated HRR early after exercise in endurance-trained athletes may be attributed to augmented parasympathetic reactivation. In the present study, we tested the hypothesis that the HRR early after submaximal exercise is related to the pre-exercise parasympathetic modulation. Methods Thirty endurance-trained athletes (20 males,50 +-7 years) and thirty control subjects (20 males,52+- 6 years) performed a submaximal exercise on acyclo-ergometer. Pre-exercise resting short-term heart rate variability (HRV) parameters in time and frequency domains were correlated with HRR during the first 30 s, 1and 2 min after cessation of exercise. Results We found that HRR was statistically significantly faster in athletes than in controls at all examination time points (p(0.05). HF, SDNN and RMSSD were statistically significantly higher in athletes than in controls(p(0.05), but other resting HRV parameters were not statistically different between groups. After 30 s, 1 and 2 min of recovery, HRR correlation with total power, HF,HFnu and RMSSD was positive, while the correlation with LF/HF was negative for small and positive for larger values.The opposite was true for SDNN. Conclusions These findings support the hypothesis that HRR early after submaximal exercise is related to resting parasympathetic modulation in the middle-aged subjects.In addition, they suggested an optimal range of HRV formaximal HRR after exercise.
COBISS.SI-ID: 31151065
We investigated the hypothesis that during tonic pain stimulus, neurovascular coupling (NVC) decreases, measuring visually evoked cerebral blood flow velocity response (VEFR) during cold pressor test (CPT) in healthy human subjects as a test. VEFR was calculated as a relative increase in blood flow velocity in the posterior cerebral artery from average values during the last 5 s of the stimulus-OFF period to average values during the last 10 s of the stimulus-ON period. Three consecutive experimental phases were compared: basal, CPT and recovery. During CPT, end-diastolic and mean VEFR increased from 20.2 to 23.6% (p ( 0.05) and from 17.5 to 20.0% (p ( 0.05), respectively.In recovery phase, end-diastolic and mean VEFR decreased to 17.7%and 15.5%, respectively. Both values were statistically significantly different from CPT phase (p ( 0.05). Compared with the basal phase, only end-diastolic VEFR was statistically significantly different in the recovery phase (p ( 0.05). Our results are consistent with the assumption that there isa change in the activity of NVC during CPT because of the modulatory influence of subcortical structures activated during tonic pain. Contrary to our expectations, the combined effect of such influences increases rather thandecreases NVC.
COBISS.SI-ID: 29112537
Sprouting of uninjured nociceptive axons was examined in young adult, middle aged and aged rats. Axon sprouting from the spared sural nerve, both into adjacent denervated skin and into end-to-side coapted nerve graft, was significantly higher in young rats than in aged rats. Cross-transplantations of the end-to-side coapted nerve grafts between young and aged rats demonstrated that axon sprouting from young recipient nerves into aged donor nerve grafts was significantly deteriorated, whereas the axon sprouting from aged recipient nerves into young donor nerve grafts was not statistically significantly affected. The levels of laminin polypeptides in peripheral nerves were 50-100% higher in young adult than in aged rats. However, the levels of peripherin, NGF isoforms and TrkA in skin, peripheral nerves and DRG, respectively, were not significantly reduced in aged rats. Therefore, impaired sprouting of nociceptive axons in aged rats is due rather to the alterations in peripheral neural pathways, than to the limited sprouting capacity of aged sensory neurons. Decreased levels of extracellular matrix components might be important in this respect.
COBISS.SI-ID: 24118745
The report presents the clinical course, neuropathology and ultrastructure of neuronal tau inclusions of four Slovene relatives with P364S MAPT mutation. P364S MAPT mutation is characterized clinically by a variable combination of frontotemporal dementia, parkinsonism and motor neurone disease of short duration, and neuropathologically by a widespread distribution of all known neuronal tau inclusions. Two-compartment CNTI is a unique characteristic of the P364S MAPT mutation.
COBISS.SI-ID: 31360985