Neurochemical characterization of the alterations in the noradrenergic afferents to the cerebellum of adult rats exposed to X-irradiation at birth.
A single dose of x-irradiation was applied on the cephalic end of newborn rats, and the alterations in the noradrenergic afferents to the cerebellum were studied 180 days later. A net increase in the noradrenaline content of cerebellum was found (122% of nonirradiated controls). The response of noradrenaline content to reserpine injection (0.9 mg/kg, i.p.) was similar in exposed and control rats. Likewise, the 3H release induced by Ro 4-1284 from cerebellar cortex slices labeled with [3H]noradrenaline was unmodified by x-rays, although a mild increase in the spontaneous efflux of 3H was found. The retention of 3H by the slices was reduced in exposed animals (58% of controls). Both the in vitro activity of tyrosine hydroxylase and the accumulation of L-3,4-dihydroxyphenylalanine (L-DOPA) were not significantly different between x-treated rats and controls. In contrast, monoamine oxidase activity was markedly reduced in x-irradiated cerebellum (38% of controls). The x-ray-induced decrease in cerebellar weight (-60%) resulted in marked increases in noradrenaline concentration (223%), tyrosine hydroxylase activity per milligram of protein (206%), and 3H retention (50%). The accumulation of L-DOPA per gram of tissue was also increased at every time considered. These data indicate that x-irradiation at birth produces a cerebellar loss not completely shared by the noradrenergic afferents, and a permanent imbalance between the noradrenergic afferent input and its target cells might eventually result.(ABSTRACT TRUNCATED AT 250 WORDS)
Dopico
A M
AM
Instituto de Investigaciones Farmacológicas, Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina, Buenos Aires.
Zieher
L M
LM
D012369:2H-Benzo(a)quinolizin-2-ol, 2-Ethyl-1,3,4,6,7,11b-hexahydro-3-isobutyl-9,10-dimethoxy- / Q000494:pharmacology; D000344:Afferent Pathways / Q000378:metabolism*; D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D002525:Cerebellar Cortex / Q000187:drug effects / Q000378:metabolism; D002531:Cerebellum / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D005260:Female; D066298:In Vitro Techniques; D007700:Kinetics; D007980:Levodopa / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012110:Reserpine / Q000494:pharmacology; D014316:Tritium; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D014316:Tritium; D012369:2H-Benzo(a)quinolizin-2-ol, 2-Ethyl-1,3,4,6,7,11b-hexahydro-3-isobutyl-9,10-dimethoxy-; D007980:Levodopa; D012110:Reserpine; D014446:Tyrosine 3-Monooxygenase; D009638:Norepinephrine