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Results of this investigation indicate that the ferret (Mustela putorius) closely resembles the dog (Canis familiaris) and should be a useful research animal alternative. The tapetum lucidum is a common structure present in the eyes of dogs, cats (Felis catus) and other nocturnal animals. Our study showed that this structure was present in ferret eyes. The color or reflection of the ferret and dog tapetum was remarkably reduced by the general fixation with glutaraldehyde. However, this color fading phenomenon was not observed in the cat tapetum. These observations led to this comparative study on several morphological, histochemical and biochemical parameters on mature ferrets, dogs and cats including: (1) the number of center tapetum cell layers, (2) thickness of center tapetum, (3) presence of a microtubule-like structure in each tapetal rod, (4) presence of electron-dense cores in tapetal rods after prolonged fixation in glutaraldehyde, (5) retention of reflection or color of tapetum after prolonged glutaraldehyde fixation, (6) zygomatic bones of eye orbits, (7) zinc content in tapetum, (8) cysteine in the tapetum, (9) cysteine sulfinic acid decarboxylase in liver, (10) thickness of retina from center tapetum, (11) anterior view of skull configuration, and (12) lateral view of skull configuration (jaw and teeth). Among these 12 parameters, ferret and dog were similar in the first nine points; ferret and cat were similar to each other only in the last two points. There was no difference in retinal thickness among these three animals. 相似文献
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Muscarinic acetylcholine receptor regulates phosphatidylcholine phospholipase D in canine brain 总被引:10,自引:0,他引:10
The hydrolytic activity of phosphatidylcholine phospholipase D in the synaptosomes from canine brain was examined using a radiochemical assay with 1,2-dipalmitoyl-sn-glycerol-3-phosphoryl[3H]choline as the exogenous substrate. The involvement of G protein(s) in regulation of this enzyme was demonstrated by a 2- to 3-fold stimulation of the basal activity (4.81 +/- 0.44 nmol choline released/mg protein/h) with guanosine 5'-(3-O-thiol)triphosphate (GTP gamma S), guanyl-5'-yl-(beta, gamma-methylene)diphosphonate, aluminum fluoride, or cholera toxin. The stimulation of phospholipase D hydrolytic activity by GTP gamma S was inhibited by 2 mM guanosine 5'-(2-O-thiol)diphosphate. GTP gamma S at the maximum stimulatory concentration (10 microM) had an additive effect on the maximum cholera toxin stimulation of phospholipase D activity. However, the reverse was not true, thus indicating the possibility that more than one G protein may be involved. Furthermore, cholinergic agonists, including acetylcholine, carbachol, and muscarine, were able to increase the phospholipase D hydrolytic activity at low but not maximally stimulatory concentrations of guanine nucleotide. These cholinergic stimulations were antagonized by atropine, a muscarinic blocker. In addition, O-tetradecanoylphorbol 13-acetate, a protein kinase C activator, was able to stimulate the hydrolytic activity of phospholipase D more than 300% in the presence of 0.2 microM GTP gamma S. However, in the absence of GTP gamma S, stimulation was less than 60%. Our results not only indicate that the receptor-G protein-regulated phospholipase D may be directly responsible for the rapid accumulation of choline and phosphatidic acid in the central nervous system but also reveal that muscarinic acetylcholine receptor-G protein-regulated phospholipase D is a novel signal transduction process coupling the neuronal muscarinic receptor to cellular responses. 相似文献