Neurochemical characteristics and behavioral responses to psychological stress in ovariectomized rats.
The present study was designed to clarify the time-dependent changes in brain monoamine turnover in the frontal cortex, hypothalamus, hippocampus, septum and amygdala after ovariectomy, and the difference in behavioral responses to psychological stress between sham-operated and ovariectomized (OVX) rats. At 2 and 4 weeks after ovariectomy, the turnover rates of dopamine and norepinephrine in all of the brain regions examined did not differ significantly between the sham-operated and OVX rats. However, 5-hydroxytryptamine (5-HT) turnover in all of the brain regions at 2 weeks after OVX was significantly lower than that in sham-operated rats. This difference was greater in the hypothalamus than in other brain regions. At 4 weeks after ovariectomy, 5-HT turnover in all of the brain regions examined was not significantly different between sham-operated and OVX rats. At 2 and 4 weeks after ovariectomy, exploratory behaviour (e.g., locomotor activity, head- dipping, crossing and rearing behaviours) in a non-stressed ovariectomy group did not differ from that in a non-stressed sham-operation group. Locomotor activity and the number of head-dips and crossings significantly (P<0.05) increased after repeated exposure to psychological stress for 5 days in sham-operated rats, but not in those at 2 weeks after OVX. At 4 weeks after ovariectomy, locomotor activity and the number of crossings and rearings in sham-operated and OVX rats were not significantly different in the psychological stress and non-stress groups. However, the number of head-dips significantly (P<0.05) increased with psychological stress in the sham-operated rats, but not in OVX rats. These results suggest that female gonadal hormones may play an important role in the regulation of brain 5-HTergic systems. These interactions between gonadal hormones and 5-HT metabolism may be related to 5-HT-related neuropsychiatric disorders.
Zhang
J
J
Department of Pharmacology, Tokyo Medical University, 6-1-1 Shinjuku, Tokyo, Shinjuku-ku, 160-8402, Japan.
Inazu
M
M
Tsuji
K
K
Yamada
E
E
Takeda
H
H
Matsumiya
T
T
D000679:Amygdala / Q000378:metabolism; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D001921:Brain / Q000378:metabolism; D001923:Brain Chemistry / Q000502:physiology*; D004298:Dopamine / Q000378:metabolism; D005106:Exploratory Behavior / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D009929:Organ Size / Q000502:physiology; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D012688:Septum Pellucidum / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism; D013315:Stress, Psychological / Q000503:physiopathology*; D014599:Uterus / Q000254:growth & development; D015430:Weight Gain / Q000502:physiology
D012701:Serotonin; D004298:Dopamine; D009638:Norepinephrine