ISSN:
1432-0878
Keywords:
Key words: Hypertonic stimulation
;
Microdialysis
;
c-fos
;
Cholecystokinin
;
Glial fibrillary acidic protein
;
Vasopressin neurones
;
Oxytocin neurones
;
Rat (Spraque Dawley)
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract. We investigated whether hypertonicity acts directly on supraoptic neurones to activate c-fos expression. Hypertonic artificial cerebrospinal fluid was infused into the supraoptic nucleus (SON) via a microdialysis probe implanted 24 h previously. The rats were decapitated after 90 min for immunohistochemistry with a Fos protein antibody. Direct hypertonic stimulation increased Fos protein expression in glial cells, identified by glial fibrillary acidic protein immunoreactivity, but not in magnocellular neurones. Similarly, with in situ hybridisation c-fos mRNA expression was predominantly seen in glial cells. Fos expression in SON neurones was stimulated by systemic hypertonicity even with a microdialysis probe in the SON, and magnocellular neurones expressed Fos after direct microinjection of cholecystokinin-8S into the SON. Thus, while direct hypertonic stimulation of SON neurones activates secretion of vasopressin and oxytocin, the c-fos gene is not activated, unlike following systemic hypertonic stimulation. This indicates that excitation of neuronal electrical and secretory activity does not necessarily lead to activation of the c-fos gene. Activation of c-fos expression in glial cells by direct hypertonic stimulation may reflect their role in regulating brain extracellular fluid composition.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004410050733
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