Endothelin-1 (ET-1) and Nerve Growth Factor (NGF) are proteins, released from cancer-ridden tissues, which cause spontaneous pain and hypersensitivity to noxious stimuli. Here we examined the electrophysiological and behavioral effects of these two agents for evidence of their interactions. Individual small-medium cultured DRG sensory neurons responded to both ET-1 (50 nM, n=6) and NGF (100 ng/ml, n=4), with increased numbers of action potentials and decreased slow K(+) currents; pre-exposure to ET-1 potentiated NGF´s actions, but not vice versa. Behaviorally, single intraplantar (i.pl.) injection of low doses of ET-1 (20 pmol) or NGF (100 ng), did not increase hindpaw tactile or thermal sensitivity, but their simultaneous injections sensitized the paw to both modalities. Daily i.pl. injections of low ET-1 doses in male rats caused tactile sensitization after 21 days, and enabled further tactile and thermal sensitization from low dose NGF, in ipsilateral and contralateral hindpaws. Single injections of 100 ng NGF, without changing the paw's tactile sensitivity by itself, acutely sensitized the ipsilateral paw to subsequent injections of low ET-1. The sensitization from repeated low ET-1 dosing and the cross-sensitization between NGF and ET-1 were both significantly greater in female than in male rats. These findings reveal a synergistic interaction between cutaneously administered low doses of NGF and ET-1, which could contribute to cancer-related pain.

• MeSH
• bolest chemicky indukované   metabolismus   MeSH
• endotelin-1 aplikace a dávkování   metabolismus   toxicita   MeSH
• fyzikální stimulace škodlivé účinky   MeSH
• hmat účinky léků   fyziologie   MeSH
• injekce subkutánní MeSH
• krysa rodu rattus MeSH
• měření bolesti metody   MeSH
• nervový růstový faktor aplikace a dávkování   metabolismus   toxicita   MeSH
• potkani Sprague-Dawley MeSH
• vazba proteinů fyziologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The period around birth is a risky time for stroke in infants, which is associated with two major acute and subacute processes: anatomical damage and seizures. It is unclear as to what extent each of these processes independently contributes to poor outcome. Furthermore, it is unclear whether there is an interaction between the two processes - does seizure activity cause additional brain damage beyond that produced by ischemia and/or does brain damage foster seizures? The model of focal cerebral ischemia induced by the intrahippocampal infusion of endothelin-1 (ET-1) in 12-day-old rat was used to examine the role of the endothelin receptors in the development of focal ischemia, symptomatic acute seizures and neurodegeneration. ET-1 (40pmol/μl) was infused either alone or co-administered with selective antagonists of ETA (BQ123; 70nmol/μl) or ETB receptors (BQ788; 70nmol/1μl). Effects of activation of ETB receptors were studied using selective agonist 4-Ala-ET-1 (40pmol/1μl). Regional cerebral blood flow (rCBF) and tissue oxygenation (pO2) were measured in anesthetized animals with a Doppler-flowmeter and a pO2-sensor, respectively. Seizure development was assessed with video-EEG in freely moving rats. Controls received the corresponding volume of the appropriate vehicle (10mM PBS or 0.01% DMSO-PBS solution; pH7.4). The extent of hippocampal lesion was determined using FluoroJade B staining performed 24h after ET-1 infusion. Infusion of ET-1 or ET-1+ETB receptor antagonist reduced rCBF to ~25% and pO2 to ~10% for about 1.5h, whereas selective ETB agonist, ET-1+ETA antagonist and the PBS vehicle had only negligible effect on the rCBF and pO2 levels. Reduction of rCBF was associated with the development of lesion in the injected hippocampus. In all groups, except sham operated and PBS controls, epileptiform activity was observed after activation of the ETA or the ETB receptors. The data revealed a positive correlation between the severity of morphological damage and all the measured seizure parameters (seizure frequency, average and total seizure duration) in the ET-1 group. In addition, the severity of morphological damage positively correlated with the average seizure duration in animals after infusion of ET-1+ETA receptor antagonist or after infusion of ET-1+ETB receptor antagonist. Our results indicate that the activation of ETA receptors is crucial for ischemia development, however either ETA or ETB receptors mediate the development of seizures following the application of ET-1 in immature rats. The dissociation between the ischemic-producing and seizure-producing processes suggests that damage is not necessary to induce seizures, although it may exacerbate them.

• MeSH
• elektroencefalografie * účinky léků   MeSH
• endotelin-1 aplikace a dávkování   toxicita   MeSH
• hipokampus účinky léků   metabolismus   MeSH
• injekce intraventrikulární MeSH
• krysa rodu rattus MeSH
• potkani Wistar MeSH
• receptor endotelinu A agonisté   metabolismus   MeSH
• receptor endotelinu B agonisté   metabolismus   MeSH
• záchvaty chemicky indukované   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• Klíčová slova
• erytropoetin, Any-maze,
• MeSH
• bludiště - učení MeSH
• cévní mozková příhoda * MeSH
• endotelin-1 aplikace a dávkování   MeSH
• erythropoetin * aplikace a dávkování   terapeutické užití   MeSH
• kognice klasifikace   účinky léků   MeSH
• kognitivní poruchy * prevence a kontrola   MeSH
• lidé MeSH
• Morrisovo vodní bludiště MeSH
• potkani Wistar MeSH
• prospektivní studie MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH

The goal of this study was to develop a new model of ischemia-induced seizures in immature rats using injection of vasoconstrictor Endothelin-1 (ET-1) into the brain. ET-1 (10, 20, or 40 pmol) was infused into the left dorsal hippocampus of freely moving Wistar rats 12 (P12) and 25 (P25) days old. Animals were then video/EEG-monitored for 100 min and monitoring was repeated 22 h later. Parameters of electrographic seizures (frequency and mean duration) as well as pattern of their behavioral correlates were evaluated. The pattern of behavioral seizures was used to develop model-specific scoring system. Cresyl violet and Fluoro Jade-B-staining were used to evaluate brain damage. Extension of the lesion was correlated with seizure severity. After ET-1-injection, seizures occurred in 83-100% animals of all age-and-dose groups and persisted for 24 h except P12 rats with 10 pmol. There were no differences in average seizure duration (18-40 s) or seizure frequency (3-7 seizures/100 min) among individual dose-groups. Between the 1st and 2nd observation period, total seizure duration decreased in 71% of P12 and 47% of P25 rats. Electrographic seizure activity was most frequently accompanied by clonus, incidence of more severe convulsions (barrel rolling or generalized clonic seizures) increased with dose of ET-1. Morphologic examination did not reveal any dose-related difference in damage severity, hippocampal damage was however more extensive in P12 compared to P25 animals. Seizure severity correlated positively with severity of the damage in both age groups. Our study presents focal injection of ET-1 into the brain as a new and practical model of ischemia-induced seizures in immature rats.

• MeSH
• elektroencefalografie statistika a číselné údaje   MeSH
• endotelin-1 aplikace a dávkování   farmakologie   MeSH
• epilepsie chemicky indukované   patofyziologie   patologie   MeSH
• financování organizované MeSH
• hipokampus patofyziologie   patologie   účinky léků   MeSH
• injekce MeSH
• ischemie mozku chemicky indukované   patofyziologie   patologie   MeSH
• krysa rodu rattus MeSH
• novorozená zvířata MeSH
• potkani Wistar MeSH
• videozáznam MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH