Effects of cocaine treatment on the nervous system of planaria (Dugesia gonocephala s. l.). Histochemical and ultrastructural observations

V. Margotta, B. Caronti, G. Meco, A. Merante, S. Ruggieri, G. Venturini, G. Palladini

Research output: Contribution to journalArticlepeer-review

Abstract

Acute high dose treatment with cocaine in planaria has been shown to produce hyperkinesia followed by immobilization, thus suggesting progressive neuronal dopamine (DA) depletion. On the contrary, treatment with low doses of cocaine inhibits motor activity in planaria, without producing hyperkinesias. Here we investigated the morpho-functional changes of the DA presynaptic terminals following cocaine treatment in planaria (acute high dose and chronic low dose). Neuronal DA content was determined by means of histochemical methods, and nerve cell ultrastructure was examined by electron microscopy. The effects of cocaine were compared to those of L-dopa, reserpine (used as positive and negative controls, respectively) and normal untreated specimens. Presynaptic vesicles and DA content were significantly reduced by chronic low-dose cocaine treatment. These effects were even more robust when the drag was acutely administered at high dose. Thus, depletion of DA vesicles is produced by cocaine in planaria, as well as in mammals. The behavioral effects of chronic low-dose treatment with cocaine, however, suggest that the drug acts not only as a DA reuptake blocker, but also as a direct agonist on presynaptic DA receptors. Acute high-dose administration of cocaine also produced signs of neuronal suffering, thus providing evidence for a direct neurotoxic effect of the drug.

Original languageEnglish
Pages (from-to)223-230
Number of pages8
JournalEuropean journal of histochemistry : EJH
Volume41
Issue number3
Publication statusPublished - 1997

Keywords

  • Catecholamines
  • Cocaine
  • Dopamine receptors
  • Planaria

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Cell Biology
  • Developmental Biology
  • Anatomy

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