Monoamines in the dorsomedial hypothalamus of rats following exposure to different tests of "anxiety".
1. Adult male Sprague-Dawley rats were subjected to the fear-potentiated startle, elevated plus-maze and social interaction tests and the levels of norepinephrine, dopamine and serotonin in the dorsomedial hypothalamus were determined by high-performance liquid chromatography. 2. Only rats subjected to the full fear potentiated startle test and not the other tests of anxiety or components (foot shocks or acoustic startle) of fear-potentiated startle showed significant increases in norepinephrine and dopamine levels after 24 hours. 3. A time course experiment specific for the norepinephrine changes in the dorsomedial hypothalamus of fear-potentiated startle rats revealed a significant increase in tissue content as compared to controls at both the 12 and 24 hour post-test time points. 4. Tyrosine hydroxylase activity in the dorsomedial hypothalamus of the fear-potentiated startle rats did not show a significant change from controls. 5. An in vitro release study found a significant decrease in potassium-stimulated release of norepinephrine in the dorsomedial hypothalamus as compared to controls at 24 hours post-test. 6. These results suggest that animals exposed to fear-potentiated startle and not other tests of "anxiety" have a change in tissue catecholamine levels and that the norepinephrine change may be the result of a decrease in release and not an increase in synthesis.
Sajdyk
T J
TJ
Department of Psychiatry, Indiana University School of Medicine, Indianapolis, USA.
Katner
J S
JS
Shekhar
A
A
D000818:Animals; D001007:Anxiety / Q000378:metabolism*; D015306:Biogenic Monoamines / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism*; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013216:Reflex, Startle / Q000502:physiology
D015306:Biogenic Monoamines; D004298:Dopamine; D009638:Norepinephrine