BRIEF REPORT |
Correspondence to: Naoyuki Kanoh, Dept. of Otolaryngology, Hyogo College of Medicine, 1-1 Mukogawacho, Nishinomiya, Hyogo 663, Japan.
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Summary |
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High doses of reserpine induce depletion of biogenic amines. The K-NPPase activity of choroid plexus was determined after one-shot reserpine administration using cerium-based cytochemistry. In normal untreated animals, reaction product was found on the microvilli of the choroidal epithelium but was almost undetectable 3 and 7 days after reserpinization. At 20 days after reserpinization, however, it was detectable. These findings suggested that reserpine decreased the choroidal Na,K-ATPase activity, and that catecholamines might be essential to maintain normal choroidal Na,K-ATPase activity. (J Histochem Cytochem 46: 975976, 1998)
Key Words: K-NPPase cytochemistry, Na,K-ATPase, catecholamine, reserpine, choroid plexus, guinea pig
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Introduction |
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Ouabain-sensitive, K+-dependent adenosine triphosphatase (Na,K-ATPase) participates in the active transport of Na+ and K+ ions. Na,K-ATPase activity is high in the choroid plexus and is responsible for the production and maintenance of the cerebrospinal fluid (
Reserpine belongs to the family of rauwolfia alkaloids and induces the release of biogenic amines. Using a cerium-based method (
The choroid plexus was obtained from 12 Hartly guinea pigs, weighing 400500 g, with a normal Prayer's reflex at 3 days (n = 3), 7 days (n = 3), and 20 days (n = 2) after one-shot reserpine administration (10 mg/kg IP) and from untreated animals (n = 4). Under deep ketamine hydrochloride anesthesia (IM), the animals were perfused through the heart with a fixative containing 2% paraformaldehyde and 0.05% glutaraldehyde in 0.1 M cacodylate buffer (pH 7.4). After decapitation, the choroid plexi were dissected from the excised brain and immersed in the same fixative for 1 hr at 4C. The tissue samples were rinsed in 50 mM Tricine buffer (pH 7.5) for 15 min and then incubated in medium according to the cerium method (
The cytochemical examination of K-NPPase activity revealed a fine granular reaction product that was found exclusively on the microvilli of normal choroidal epithelium (Figure 1A). In choroid plexus 3 days after reserpinization (Figure 1B) and 7 days after reserpinization (Figure 1C), enzyme reaction product was almost undetectable. However, at 20 days after reserpinization reaction product was detectable (Figure 1D). The formation of reaction product was almost completely inhibited when 10 mM ouabain was included in the medium (Figure 2A), and reaction product was undetectable in a substrate-free medium (Figure 2B), and in a medium in which K+ had been replaced with Na+ (Figure 2C).
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Controlling the CSF volume and electrolyte composition is necessary for normal neural functioning and is essential for maintaining physiological brain volume and intracranial pressure (
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Acknowledgments |
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Supported by a Grant-in-Aid (08671998) for Science Research from the Ministry of Education, Science and Culture of Japan.
Received for publication March 2, 1998; accepted March 3, 1998.
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