Effects of repeated stress on regeneration of serotonergic and noradrenergic axons in the cerebral cortex of adult rats.
We examined whether regeneration of serotonergic (5-HT) and noradrenergic (NA) axons might be affected by stress. Neurotoxins to 5-HT or NA axons were injected into the frontal cortex to cause partial denervation. Mild restraint stress (40 min/day) was started 16 days later and given for 14 consecutive days (30-day stressed group). Non-stressed animals were divided into two groups, animals sacrificed at 14 days (14-day control group) and those sacrificed at 30 days (30-day control group) after the toxin injection. In immunohistochemical study, the denervation area of 5-HT axons but not that of NA axons was significantly smaller in the 30-day control group than in the 14-day control group. However, there was no significant difference between the 14-day control and 30-day stressed groups. These findings suggested that regeneration of 5-HT axons occurred earlier than that of NA axons, and that stress exerted inhibitory influence on regeneration of 5-HT axons.
Liu
Ying
Y
Department of Neuroscience, Yamaguchi University School of Medicine, Ube, Yamaguchi 755-8505, Japan.
Ishida
Yoshiyuki
Y
Shinoda
Koh
K
Nakamura
Shoji
S
D000818:Animals; D001369:Axons / Q000502:physiology*; D002540:Cerebral Cortex / Q000502:physiology; D002908:Chronic Disease; D008297:Male; D009416:Nerve Regeneration / Q000502:physiology*; D009638:Norepinephrine / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000502:physiology*; D013312:Stress, Physiological / Q000503:physiopathology*
D012701:Serotonin; D009638:Norepinephrine