Korean J Aerosp Environ Med.  2003 Mar;13(1):7-12.

Changes in Hypothalamic Expressions of Natriuretic Peptide mRNA following Head-down Suspension in Rats

• Bae JH
• Song DK
• Shin DH

Abstract

BACKGROUND
Head-down suspension (HDS) of rats has been used as a model for simulation of a microgravity environment. C-type natriuretic peptides (CNP) and atrial natriuretic peptide (ANP) are produced in the central nervous system, especially in hypothalamus, to complement their peripheral natriuretic effects. Therefore, this study investigated the changes in the central adaptations of hypothalamic ANP and CNP syntheses to 4 weeks of HDS in rats.
METHODS
Unanesthetized, unrestrained, male Sprague-Dawley rats were subjected to either a horizontal position (control rats) or a -45 degrees head-down tilt using the tail-traction technique (HDS rats). We determined the hypothalamic syntheses of natriuretic peptides as an expression of ANP and CNP mRNA. The expression of natriuretic peptide mRNA was measured by reverse transcription-polymerase chain reaction with [32P]-dCTP following 4 weeks of HDS in the hypothalamus of control and HDS rats.
RESULTS
After 4 weeks of HDS, the expression of ANP mRNA showed a decreasing trend in the hypothalamus of HDS rats. In contrast with ANP, CNP mRNA expression was significantly (p<0.01) increased in the hypothalamus of HDS rats. There were different changes in the hypothalamic CNP and ANP mRNA expressions of HDS rats compared with that of the control rats.CONCLUSION: These results represent that the hypothalamic syntheses of natriuretic peptides are differently responded and the role of CNP is augmented to compensate for the decrement of ANP action in the central nervous system following 4 weeks of HDS.

Keyword

Head-down suspension; CNP and ANP mRNA; Hypothalamus

MeSH Terms

Animals
Atrial Natriuretic Factor
Central Nervous System
Complement System Proteins
Head-Down Tilt
Humans
Hypothalamus
Male
Natriuretic Agents
Natriuretic Peptides
Rats*
Rats, Sprague-Dawley
RNA, Messenger*
Weightlessness
Atrial Natriuretic Factor
Complement System Proteins
Natriuretic Agents
Natriuretic Peptides
RNA, Messenger