Degeneration of monoaminergic fibers in the aged micrencephalic rat.
Age-related changes in the monoaminergic neuron systems in the brains of methylazoxymethanol acetate (MAM)-induced micrencephalic rats were studied. Neurochemical analysis revealed high levels of serotonin, norepinephrine and associated metabolites in several brain areas of MAM-treated rats. In particular, serotonin levels in the frontal cortex, cingulate cortex and hippocampus of 12-month-old (12 M) MAM-treated rats were significantly higher than in corresponding age-matched controls. Immunohistochemical analysis demonstrated numerous aberrant serotonin-immunoreactive fibers and small numbers of aberrant tyrosine hydroxylase-immunoreactive fibers in the septum, caudate putamen, thalamus, cerebral cortex, hippocampus and midbrain tegmentum of 12 M MAM-treated rats. Aberrant monoaminergic fibers characterized by swollen varicosities and thickening of intervaricose segments were common compared to 12 M control rats. In the cortex and hippocampus of 12 M MAM-treated rats, aberrant fibers were observed near cortical heterotopic tissue. These results indicate early onset of age-related degeneration of monoaminergic fibers in micrencephalic rats. Aged MAM-treated rats may thus offer a good model for studying age-related monoaminergic changes in the cortical heterotopic tissue of human cortical malformations.
Watabe
Yoshiyuki
Y
Department of Pediatrics, Dokkyo University School of Medicine, Mibu, Tochigi 321-0293, Japan.
Yoshimoto
Kanji
K
Eguchi
Mitsuoki
M
Ueda
Shuichi
S
D000375:Aging / Q000378:metabolism*; D000818:Animals; D015306:Biogenic Monoamines / Q000378:metabolism*; D001923:Brain Chemistry / Q000187:drug effects / Q000502:physiology*; D001930:Brain Injuries / Q000139:chemically induced / Q000150:complications / Q000473:pathology; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005260:Female; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D008746:Methylazoxymethanol Acetate; D009410:Nerve Degeneration / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D009412:Nerve Fibers / Q000378:metabolism* / Q000473:pathology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D015306:Biogenic Monoamines; D008746:Methylazoxymethanol Acetate