"PL146" Dotaz Zobrazit nápovědu

Přesná shoda Sémantické

Stereological methods, using the principle of point counting and unbiased counting frames, for the estimation of muscle area, total fibre area, number of muscle fibres and mean fibre area are described in detail. Their practical application is demonstrated on cross-sections of the rat soleus muscles. It is shown that the efficiency of these methods is high and their results are comparable with those achieved by the conventional manual and image analysis methods. The main advantages of two-dimensional stereological methods in muscle morphometry are pointed out: measurements are made directly on specimens under the microscope and in the simplest implementation do not require sophisticated and expensive technical equipment. Furthermore, unbiased results are obtained, no segmentation and edge effect problems arise and the quantity of work invested in stereological estimation is reasonable. Based upon the study of the efficiency of used stereological methods, a suitable test system for muscle morphometry is proposed.

MeSH
histologické techniky MeSH
kosterní svalová vlákna cytologie enzymologie MeSH
kosterní svaly cytologie enzymologie MeSH
krysa rodu rattus MeSH
myosiny analýza metabolismus MeSH
zkreslení výsledků (epidemiologie) MeSH
zvířata MeSH
Check Tag
krysa rodu rattus MeSH
zvířata MeSH
Publikační typ
časopisecké články MeSH
práce podpořená grantem MeSH
srovnávací studie MeSH

Článek online

Neurokinin 1 and 2 antagonists attenuate the responses and NK1 antagonists prevent the sensitization of primate spinothalamic tract neurons after intradermal capsaicin

Journal of neurophysiology. 1994 ; 72 (4) : 1464-1175.

J Neurophysiol
ISSN 0022-3077
Medvik
Zdroj

1. Activation of neurokinin receptors contributes to the excitation of many dorsal horn neurons by cutaneous sensory stimuli, particularly noxious stimuli. In the present study we investigate the role of neurokinin receptors in the activation of primate spinothalamic tract (STT) neurons by cutaneous mechanical stimuli and by intradermal injection of capsaicin. This was done by testing the responses of these neurons to a battery of cutaneous stimuli before and during infusion by microdialysis of antagonists selective for NK1 and NK2 receptors. 2. The NK1 receptor antagonists cis-3-(2-methoxybenzyl-amino-2-benzhydrylquinuclidine (CP96345) and D-Pro9-[Spiro-y-lactam]-Leu10,Trp11)-Physalaemin(1-11) (GR82334) did not significantly reduce the responses of STT cells to mechanical stimulation of the skin. Both NK1 antagonists did, however, produce a significant reduction in the responses of STT neurons to an intradermal injection of capsaicin. Finally, despite having no effects on responses to mechanical stimuli, both NK1 antagonists prevented the sensitization of the responses to cutaneous stimuli that is usually observed after intradermal injections of capsaicin. 3. The NK2 selective antagonists PhCO-Ala-Ala-D-Trp-Phe-D-Pro-Pro-Nle-NH2 (GR98400) and [Tyr5,D-Trp6,8,9,Lys10]-NKA (4-10) (MEN10376) had effects very similar to those of the NK1 antagonists, but with an important difference. Neither NK2 antagonist affected the responses of STT neurons to noxious or innocuous mechanical stimulation of the skin, but they did reduce the responses to intradermal capsaicin injections. These compounds failed to prevent capsaicin-induced sensitization. In fact, cells exposed to GR98400 or MEN10376 showed unusually sustained increases in the responses to mechanical stimuli after the first capsaicin injection, suggesting that these compounds actually induced sensitization. 4. These results support the contention that both neurokinin receptors participate in the processing of nociceptive information in the dorsal horn, especially responses to strong stimuli such as intradermal injection of capsaicin. NK1 receptors are also involved in the sensitization of STT neurons after peripheral injury. A clearer understanding of the role of NK2 receptors in sensitization requires further studies with improved antagonists.

Článek online

The effect of trans-ACPD, a metabotropic excitatory amino acid receptor agonist, on the responses of primate spinothalamic tract neurons

Pain. 1994 ; 56 (3) : 261-269.

ISSN 0304-3959
Medvik
Zdroj

The responses of primate spinothalamic tract (STT) neurons to innocuous and noxious mechanical stimuli applied to the skin can be enhanced for more than an hour following prolonged noxious stimulation. This increased responsiveness is thought to reflect sensitization of dorsal horn neurons and may help account for secondary hyperalgesia and mechanical allodynia. The proposal that central sensitization is due to the activation of second messenger system was tested in this study by examining the effect of trans-ACPD (trans-D,L-1-amino-1,3-cyclopentanedicarboxylic acid), an agonist of metabotropic excitatory amino acid (EAA) receptors, introduced into the dorsal horn by microdialysis. A low dose of trans-ACPD resulted in an increase in the responses of STT cells to an innocuous mechanical stimulus (BRUSH), but no increase in the responses to noxious mechanical and thermal stimuli or in the excitation produced by iontophoretically applied EAAs. A high dose of trans-ACPD caused a transient increase in background activity, but no change in the responsiveness of spinothalamic cells to any of the test stimuli. It is concluded that low doses of trans-ACPD can selectively enhance transmission through interneuronal pathways mediating tactile inputs to spinothalamic cells.

Článek online

The effect of phorbol esters on the responses of primate spinothalamic neurons to mechanical and thermal stimuli

Journal of neurophysiology. 1994 ; 71 (2) : 529-537.

J Neurophysiol
ISSN 0022-3077
Medvik
Zdroj

1. Sensitization of dorsal horn neurons is thought to play an important role in pain perception, secondary hyperalgesia, and allodynia. Recent experimental evidence suggests that the sensitization of dorsal horn neurons is induced by combined increased release of excitatory amino acids and peptides in the spinal cord dorsal horn from nociceptive primary afferents due to an injury-caused barrage of impulses. We tested the hypothesis that protein kinase C (PKC) is involved as a second messenger in this process of neuronal sensitization. To activate PKC, infusion of a phorbol ester [12-O-tetradecanoylphorbol-13-acetate (TPA)] into the dorsal horn through a microdialysis fiber was used. During TPA infusion the background activity of spinothalamic (STT) neurons increased substantially. After TPA application, while the background activity of the STT neurons was still increased, the responses evoked by either innocuous or noxious mechanical stimulation of the cutaneous receptive field did not change from the control level. However, 1 h after TPA administration the background activity returned to the control level and responses to innocuous mechanical stimuli were significantly elevated. The responses of STT cells to noxious heat and noxious mechanical stimuli did not change significantly after TPA administration. When a phorbol ester that does not activate PKC was applied (alpha-TPA), no significant changes in background or evoked activity of STT cells were observed. Our results provide evidence that PKC may play an important role in the process of sensitization of dorsal horn neurons to innocuous mechanical stimuli.