Increased activity of tyrosine hydroxylase in the cerebellum of the x-irradiated dystonic rat

Journal Article · Wed Aug 01 00:00:00 EDT 1990 · Molecular and Chemical Neuropathology; (United States)

DOI:https://doi.org/10.1007/BF03159914· OSTI ID:5395712

Dopico, A M; Rios, H; Mayo, J; Zieher, L M ^[1]

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1. Departamentos de Biologia Celular e Histologia y de Farmacologia y Toxicologia, Facultad de Medicina, Universidad de Buenos Aires, (Argentina)

The exposure of the cephalic end of rats to repeated doses of x-irradiation (150 rad) immediately after birth induces a long-term increase in the noradrenaline (NA) content of cerebellum (CE) (+ 37.8%), and a decrease in cerebellar weight (65.2% of controls), which results in an increased NA concentration (+ 109%). This increase in the neurotransmitter level is accompanied by a dystonic syndrome and histological abnormalities: Purkinje cells (the target cells for NA afferents to CE) fail to arrange in a characteristic monolayer, and their primary dendritic tree appears randomly oriented. The injection of reserpine 0.9 and 1.2 mg/kg ip to adult rats for 18 h depletes cerebellar NA content in both controls (15.7 {plus minus} 4 ng/CE and 2.8 {plus minus} 1.5 ng/CE, respectively) and x-irradiated rats (17.1 {plus minus} 1 ng/CE and 8.3 {plus minus} 2 ng/CE, respectively). The activity of tyrosine hydroxylase (TH) in CE of adult rats, measured by an in vitro assay, is significantly increased in neonatally x-irradiated animals when compared to age-matched controls (16.4 {plus minus} 1.4 vs 6.32 {plus minus} 0.6 nmol CO2/h/mg prot., p less than 0.01). As observed for NA levels, a net increase in TH activity induced by the ionizing radiation is also measured: 308.9 {plus minus} 23.8 vs 408.2 {plus minus} 21.5 nmol CO2/h/CE, p less than 0.01 (controls and x-treated, respectively). These results suggest that x-irradiation at birth may induce an abnormal sprouting of noradrenergic afferents to CE. The possibility that these changes represent a response of the NA system to the dystonic syndrome is discussed.

• OSTI ID: 5395712
• Journal Information: Molecular and Chemical Neuropathology; (United States), Vol. 13:1-2; ISSN 1044-7393
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
CEREBELLUM
BIOLOGICAL RADIATION EFFECTS
HYDROXYLASES
ENZYME ACTIVITY
NORADRENALINE
BIOSYNTHESIS
BIOLOGICAL PATHWAYS
NEONATES
RADIATION DOSES
RATS
TYROSINE
X RADIATION
ADRENAL HORMONES
AMINO ACIDS
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BIOLOGICAL EFFECTS
BODY
BRAIN
CARBOXYLIC ACIDS
CARDIOTONICS
CARDIOVASCULAR AGENTS
CENTRAL NERVOUS SYSTEM
DOSES
DRUGS
ELECTROMAGNETIC RADIATION
ENZYMES
HORMONES
HYDROXY ACIDS
IONIZING RADIATIONS
MAMMALS
NERVOUS SYSTEM
NEUROREGULATORS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
OXIDOREDUCTASES
RADIATION EFFECTS
RADIATIONS
RODENTS
SYMPATHOMIMETICS
SYNTHESIS
VERTEBRATES
560152* - Radiation Effects on Animals- Animals