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

Alejandro Dopico, Hugo Ríos, José Mayo, Luis M. Zieher

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Abstract

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±4 ng/CE and 2.8±1.5 ng/CE, respectively) and X-irradiated rats (17.1±1 ng/CE and 8.3±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 agematched controls (16.4±1.4 vs 6.32±0.6 nmol CO2/h/mg prot., p<0.01). As observed for NA levels, a net increase in TH activity induced by the ionizing radiation is also measured: 308.9±23.8 vs 408.2±21.5 nmol CO2/h/CE, p<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.

Original languageEnglish (US)
Pages (from-to)129-143
Number of pages15
JournalMolecular and Chemical Neuropathology
Volume13
Issue number1-2
DOIs
StatePublished - Aug 1 1990
Externally publishedYes

Fingerprint

Tyrosine 3-Monooxygenase
Cerebellum
Norepinephrine
Parturition
Purkinje Cells
Reserpine
Ionizing Radiation
Neurotransmitter Agents
Head
Weights and Measures
Injections

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology

Cite this

Increased activity of tyrosine hydroxylase in the cerebellum of the X-irradiated dystonic rat. / Dopico, Alejandro; Ríos, Hugo; Mayo, José; Zieher, Luis M.

In: Molecular and Chemical Neuropathology, Vol. 13, No. 1-2, 01.08.1990, p. 129-143.

Research output: Contribution to journalArticle

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