Background Ca^2＋ in the central nervous system plays important roles in brain physiology, including neuronal survival and regeneration in rats with injured facial motoneurons. The present research was to study the mo...Background Ca^2＋ in the central nervous system plays important roles in brain physiology, including neuronal survival and regeneration in rats with injured facial motoneurons. The present research was to study the modulations of intracellular free Ca^2＋ concentrations by cholinergic receptors in rat facial nucleus, and the mechanisms of the modulations. Methods The fluorescence intensity of facial nucleus in Fluo-3 AM loaded acute brainstem slices was detected by applying intracellular free Ca^2＋ measurement technique via confocal laser scanning microscope. The changes of fluorescence intensity of facial nucleus indicate the average changes of intracellular free Ca^2＋ levels of the neurons. Results Acetylcholine was effective at increasing the fluorescence intensity of facial nucleus. Muscarine chloride induced a marked increase of fluorescence intensity in a concentration dependent fashion. The enhancement of fluorescence intensity by muscarine chloride was significantly reduced by thapsigargin （depletor of intracellular Ca^2＋ store; P 〈0.01）, rather than Ca^2＋ free artifical cerebrospinal fluid or EGTA （free Ca^2＋ chelator; P〉0.05）. And the increase of fluorescence intensity was also significantly inhibited by pirenzepine （M1 subtype selective antagonist; P 〈0.01） and 4-DAMP （M3 subtype selective antagonist; P 〈0.01）. In addition, fluorescence intensity was markedly increased by nicotine. The enhancement of fluorescence intensity by nicotine was significantly reduced by EGTA, nifedipine （L-type voltage-gated Ca^2＋ channel blocker）, dihydro-β-erythroidine （α4β2 subtype selective antagonist）, and in Ca^2＋ free artificial cerebrospinal fluid （P 〈0.01）, but not in the presence of mibefradil （M-type voltage-gated Ca^2＋ channel blocker） or thapsigargin （P〉0.05）. Conclusions The data provide the evidence that muscarinic receptors may induce the increase of intracellular free Ca^2＋ levels through the Ca^2＋ release of intracellular Ca^2＋ stores, in a manner related to M1 and M3 subtypes of muscarinic receptors in rat facial nucleus. Nicotine may increase intracellular free Ca^2＋ concentrations via the influx of extracellular Ca^2＋ mainly across L-type voltacle-clated Ca^2＋ channels, in a manner related to the α4β2 subtype of nicotinic receptors.展开更多
基金This work was supported by a grant from the Youth Science Foundation of Qingdao University （No. 2007）.
文摘Background Ca^2＋ in the central nervous system plays important roles in brain physiology, including neuronal survival and regeneration in rats with injured facial motoneurons. The present research was to study the modulations of intracellular free Ca^2＋ concentrations by cholinergic receptors in rat facial nucleus, and the mechanisms of the modulations. Methods The fluorescence intensity of facial nucleus in Fluo-3 AM loaded acute brainstem slices was detected by applying intracellular free Ca^2＋ measurement technique via confocal laser scanning microscope. The changes of fluorescence intensity of facial nucleus indicate the average changes of intracellular free Ca^2＋ levels of the neurons. Results Acetylcholine was effective at increasing the fluorescence intensity of facial nucleus. Muscarine chloride induced a marked increase of fluorescence intensity in a concentration dependent fashion. The enhancement of fluorescence intensity by muscarine chloride was significantly reduced by thapsigargin （depletor of intracellular Ca^2＋ store; P 〈0.01）, rather than Ca^2＋ free artifical cerebrospinal fluid or EGTA （free Ca^2＋ chelator; P〉0.05）. And the increase of fluorescence intensity was also significantly inhibited by pirenzepine （M1 subtype selective antagonist; P 〈0.01） and 4-DAMP （M3 subtype selective antagonist; P 〈0.01）. In addition, fluorescence intensity was markedly increased by nicotine. The enhancement of fluorescence intensity by nicotine was significantly reduced by EGTA, nifedipine （L-type voltage-gated Ca^2＋ channel blocker）, dihydro-β-erythroidine （α4β2 subtype selective antagonist）, and in Ca^2＋ free artificial cerebrospinal fluid （P 〈0.01）, but not in the presence of mibefradil （M-type voltage-gated Ca^2＋ channel blocker） or thapsigargin （P〉0.05）. Conclusions The data provide the evidence that muscarinic receptors may induce the increase of intracellular free Ca^2＋ levels through the Ca^2＋ release of intracellular Ca^2＋ stores, in a manner related to M1 and M3 subtypes of muscarinic receptors in rat facial nucleus. Nicotine may increase intracellular free Ca^2＋ concentrations via the influx of extracellular Ca^2＋ mainly across L-type voltacle-clated Ca^2＋ channels, in a manner related to the α4β2 subtype of nicotinic receptors.
