J Korean Neuropsychiatr Assoc.  2000 Jan;39(1):190-198.

The Effects of Repeated Stress on the GABAergic Neurotransmission in Rats

• Kim CS
• Lee JB
• Sung HM
• See HS
• Kim JS
• Park HB
• Cheung SD
• Ha JH

Abstract

OBJECTIVES
Changes of GABAergic neurotransmission in response to the application of different types of environmental stress have been the subject of research for over two decades. However, the nature of the changes induced by stress appear to show a dependent phenomena on the type and duration of stressor agent employed.
METHODS
For this reason, this study was performed to observe the effects of repeated stress on the radioligands binding to GABA A/benzodiazepine receptors of discrete brain regions. The author also examined the activity of GABA transaminase and the concentration of endogenous GABA. Male Sprague-Dawley rats, weighing 150-200g were forced to suffer an immobilization stress for 2 hours during 14 consecutive days.
RESULTS
Repeated immobilization stress decreased the binding of [3H]flunitrazepam on the benzodiazepine receptor in the cortex, hippocampus and hypothalamus. Saturation experiments followed by scatchard analyses of the results showed decreased density of benzodiazepine receptor and the affinity remained unchanged. Repeated immobilization stress did not affect the binding of [3H]muscimol on the GABAA receptor, the activity of GABA transaminase, and the concentration of endogenous GABA in the brain regions.
CONCLUSIONS
From these results, it can be concluded that repeated immobilization stress modulated GABAergic neurotransmission via downregulation of the benzodiazepine receptor in the brain.

Keyword

Repeated stress; GABA receptor; GABA transaminase

MeSH Terms

4-Aminobutyrate Transaminase
Animals
Brain
Down-Regulation
gamma-Aminobutyric Acid
Hippocampus
Humans
Hypothalamus
Immobilization
Male
Rats*
Rats, Sprague-Dawley
Receptors, GABA
Receptors, GABA-A
Synaptic Transmission*
4-Aminobutyrate Transaminase
Receptors, GABA
Receptors, GABA-A
gamma-Aminobutyric Acid