Biochemistry of Somatodendritic Dopamine Release in Substantia Nigra: An In Vivo Comparison with Striatal Dopamine Release
Version of Record online: 23 NOV 2002
Journal of Neurochemistry
Volume 65, Issue 1, pages 192–200, July 1995
How to Cite
Heeringa, M. J. and Abercrombie, E. D. (1995), Biochemistry of Somatodendritic Dopamine Release in Substantia Nigra: An In Vivo Comparison with Striatal Dopamine Release. Journal of Neurochemistry, 65: 192–200. doi: 10.1046/j.1471-4159.1995.65010192.x
- Issue online: 23 NOV 2002
- Version of Record online: 23 NOV 2002
- Received September 15, 1994; revised manuscript received January 12, 1995; accepted January 23, 1995.
- Substantia nigra;
Abstract: The somatodendritic release of dopamine in substantia nigra previously has been suggested to be nonvesicular in nature and thus to differ from the classical, exocytotic release of dopamine described for the dopaminergic nerve terminal in striatum. We have compared the effects of reserpine, a compound that disrupts vesicular sequestration of monoamines, on the storage and release of dopamine in substantia nigra and striatum of rats. Reserpine administration (5 mg/kg, i.p.) significantly decreased the tissue level of dopamine in substantia nigra pars reticulata, substantia nigra pars compacta, and striatum. In these brain areas, reserpine-induced reductions in tissue dopamine level occurred within 2 h and persisted at 24 h postdrug. In vivo measurements using microdialysis revealed that reserpine administration rapidly decreased the extracellular dopamine concentration to nondetectable levels in substantia nigra as well as in striatum. In both structures, it was observed that reserpine treatment significantly attenuated the release of dopamine evoked by a high dose of amphetamine (10 mg/kg, i.p.) given 2 h later. In contrast, dopamine efflux in response to a low dose of amphetamine (2 mg/kg, i.p.) was not altered by reserpine pretreatment either in substantia nigra or in striatum. The present data suggest the existence, both at the somatodendritic and at the nerve terminal level, of a vesicular pool of dopamine that is the primary site of transmitter storage and that can be displaced by high but not low doses of amphetamine. The physiological release of dopamine in substantia nigra and in striatum is dependent on the integrity of this vesicular store.