The role of cortico-tectal pathways in auditory signal processing was studied in anesthetized rats by comparing the extracellular single unit activity in the inferior colliculus (IC) before and after functional ablation of the auditory cortex (AC) by tetrodotoxin (TTX). The responses of several IC neurons to sound stimuli were simultaneously recorded with a 16-channel electrode probe introduced into the IC. Click-evoked middle latency responses (MLR) recorded from the AC were suppressed for several hours after TTX injection. During AC inactivation the firing rate of IC neurons increased (40 % of neurons), decreased (44 %) or did not change (16 %) in comparison with control conditions. In several IC neurons, TTX injection resulted in alterations in the shape of the rate-level functions. Response thresholds, tuning properties and the type of discharge pattern of IC neurons were not altered during AC inactivation. However, in one-third of the neurons, the initial part of the response was less altered than the later, sustained part. In two-thirds of neuronal pairs, functional decortication resulted in a change in the cross-correlation coefficient. The results reveal the complex changes that appear in IC neuronal activity after functional ablation of the ipsilateral auditory cortex., J. Popelář, F. C. Nwabueze-Ogbo, J. Syka., and Obsahuje bibliografii
Salusin-β is newly identified bioactive peptide of 20 amino acids, which is widely distributed in hematopoietic system, endocrine system, and the central nervous system (CNS). Although salusin- β extensively expressed in the CNS, the central cardiovascular functions of salusin-β are unclear. Our main objective was to determine the cardiovascular effect of microinjection of salusin-β into the nucleus tractus solitarii (NTS) in anesthetized rats. Bilateral or unilateral microinjection of salusin-β (0.94-94 μg/rat) into the NTS dose-dependently decreased blood pressure and heart rate. Bilateral NTS microinjection of salusin-β (9.4 μg/rat) did not alter baroreflex sensitivity. Prior application of the glutamate receptor antagonist kynurenic acid (0.19 μg/rat, n=9) into the NTS did not alter the salusin-β (9.4 μg/rat) induced hypotension and bradycardia. However, pretreatment with the GABA receptor agonist muscimol (0.5 ng/rat) within the rostral ventrolateral medulla (RVLM) completely abolished the hypotension (-14±5 vs. -3±5 mm Hg, P <0.05) and bradycardia (-22±6 vs. -6±5 bpm, P <0.05) evoked by intra-NTS salusin-β (9.4 μg/rat). In addition, we found that vagotomy didn’t influence the actions of salusin-β (9.4 μg/rat) in the NTS. In conclusion, our present study shows that microinjection of salusin-β into the NTS significantly produces hypotension and bradycardia, presumably by suppressing the activities of presympathetic neurons in the RVLM., Y. Lu, Y. S. Wu, D. S. Chen, M. M. Wang, W. Z. Wang, W. J. Yuan., and Obsahuje bibliografii
This review summarizes recent information on the role of calcium in the process of neuronal injury with special attention to the role of calcium stores in the endoplasmic reticulum (ER). Experimental results present evidence that ER is the site of complex processes such as calcium storage, synthesis and folding of proteins and cell response to stress. ER function is impaired in many acute and chronic diseases of the brain which in turn induce calcium store depletion and conserved stress responses. Understanding the mechanisms leading to ER dysfunction may lead to recognition of neuronal protection strategies., J. Lehotský, P. Kaplán, E. Babušíková, A. Strapková, R. Murín., and Obsahuje bibliografii
To understand the contribution of potassium (K+) channels, particularly α-dendrotoxin (D-type)-sensitive K+ channels (Kv.1, Kv1.2 or Kv1.6 subunits), to the generation of neuronal spike output we must have detailed information of the functional role of these channels in the neuronal membrane. Conventional intracellular recording methods in current clamp mode were used to identify the role of α-dendrotoxin (α-DTX)-sensitive K+ channel currents in shaping the spike output and modulation of neuronal properties of cerebellar Purkinje neurons (PCs) in slices. Addition of α-DTX revealed that D-type K+ channels play an important role in the shaping of Purkinje neuronal firing behavior. Repetitive firing capability of PCs was increased following exposure to artificial cerebrospinal fluid (aCSF) containing α-DTX, so that in response to the injection of 0.6 nA depolarizing current pulse of 600 ms, the number of action potentials insignificantly increased from 15 in the presence of 4-AP to 29 action potentials per second after application of DTX following pretreatment with 4-AP. These results indicate that D-type K+ channels (Kv.1, Kv1.2 or Kv1.6 subunits) may contribute to the spike frequency adaptation in PCs. Our findings suggest that the activation of voltage-dependent K+ channels (D and A types) markedly affect the firing pattern of PCs., H. Haghdoust, M. Janahmadi, G. Behzadi., and Obsahuje bibliografii a bibliografické odkazy
Spatial navigation and memory is considered to be a part of the declarative memory system and it is widely used as an animal model of human declarative me mory. However, spatial tests typically involve only static settings, despite the dynamic nature of the real world. Animals, as well as people constantly need to interact with moving objects, other subjects or even with entire moving environments (flowing water, running stairway). Therefore, we design novel spatial tests in dynamic environments to study brain mechanisms of spatial processing in more natural settings with an interdisciplinary approach including neuropharmacology. We also translate data from neuropharmacological studies and animal models into development of novel therapeutic approaches to neuropsychiatric disorders and more sensitive screening tests for impairments of memory, thought, and behavior., A. Stuchlik ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy