Neurochemical Characterization of the Alterations in the Noradrenergic Afferents to the Cerebellum of Adult Rats Exposed to X‐Irradiation at Birth

Alejandro Dopico, Luis M. Zieher

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Abstract

Abstract: 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. In spite of the enhanced noradrenaline content, the lack of increase in maximal tyrosine hydroxylase activity and 3H retention seems to indicate that a long‐term sprouting of the noradrenergic terminals in the cerebellum induced by the ionizing treatment is unlikely.

Original languageEnglish (US)
Pages (from-to)481-489
Number of pages9
JournalJournal of Neurochemistry
Volume61
Issue number2
DOIs
StatePublished - Jan 1 1993

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Cerebellum
Rats
Norepinephrine
Parturition
Tyrosine 3-Monooxygenase
2-Ethyl-1,3,4,6,7,11b-hexahydro-3-isobutyl-9,10-dimethoxy-2H-benzo(a)quinolizin-2-ol
Rat control
Cerebellar Cortex
Reserpine
Monoamine Oxidase
Animals
Head
X-Rays
Tissue
Weights and Measures
Injections
Proteins
Therapeutics

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Cellular and Molecular Neuroscience

Cite this

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title = "Neurochemical Characterization of the Alterations in the Noradrenergic Afferents to the Cerebellum of Adult Rats Exposed to X‐Irradiation at Birth",
abstract = "Abstract: 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. In spite of the enhanced noradrenaline content, the lack of increase in maximal tyrosine hydroxylase activity and 3H retention seems to indicate that a long‐term sprouting of the noradrenergic terminals in the cerebellum induced by the ionizing treatment is unlikely.",
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N2 - Abstract: 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. In spite of the enhanced noradrenaline content, the lack of increase in maximal tyrosine hydroxylase activity and 3H retention seems to indicate that a long‐term sprouting of the noradrenergic terminals in the cerebellum induced by the ionizing treatment is unlikely.

AB - Abstract: 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. In spite of the enhanced noradrenaline content, the lack of increase in maximal tyrosine hydroxylase activity and 3H retention seems to indicate that a long‐term sprouting of the noradrenergic terminals in the cerebellum induced by the ionizing treatment is unlikely.

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