In vivo serotonin release and learned helplessness.
Learned helplessness, a behavioral depression caused by exposure to inescapable stress, is considered to be an animal model of human depressive disorder. Like human depression, learned helplessness has been associated with a defect in serotonergic function, but the nature of this relationship is not entirely clear. We have used in vivo microdialysis brain perfusion to measure serotonin (5-hydroxytryptamine, 5HT) in extracellular space of medial frontal cortex in conscious, freely moving rats. Basal 5HT levels in rats perfused before exposure to tail-shock stress did not themselves correlate with subsequent learned helplessness behavior. However, 5HT release after stress showed a significant increase with helpless behavior. These data support the hypothesis that a cortical serotonergic excess is causally related to the development of learned helplessness.
Petty
F
F
Mental Health Clinic, Dallas Veterans Affairs Medical Center, TX.
Kramer
G
G
Wilson
L
L
Jordan
S
S
D000818:Animals; D001143:Arousal / Q000502:physiology; D004195:Disease Models, Animal; D004597:Electroshock; D005110:Extracellular Space / Q000502:physiology; D005625:Frontal Lobe / Q000502:physiology*; D006380:Helplessness, Learned; D008297:Male; D017551:Microdialysis; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000502:physiology*
D012701:Serotonin