Intracellular recording from dopamine neurons in the substantia nigra: double labelling for identification of projection site and morphological features.
We have adapted an intracellular recording technique that allows differentiation of dopamine neurons in vitro based on their projection sites and morphology. We pre-labelled 'nigrostriatal' dopamine neurons in vivo by stereotaxically injecting rhodamine-labelled microspheres (RFM) into the dorsal striatum. Following slice preparation, dense neuronal labelling with RFM was observed in the medial two-thirds of the substantia nigra zona compacta. The visible neurons in the superficial layers were not viable; consequently, we recorded from dopamine neurons that were located directly below the clusters of fluorescent neurons. Each recorded neuron was subsequently filled with N-(2-aminoethyl) biotinamide (1) to confirm whether it projected to the dorsal striatum (by presence of both RFM and biotinamide) and (2) to examine its morphological features. Four of 7 dopamine neurons successfully recovered were double labelled and exhibited multipolar cell bodies with dendrites projecting into the zona reticulata. No differences in the resting membrane potential, spontaneous activity, or membrane response to constant current injections were observed between the confirmed nigrostriatal dopamine neurons and the others. Our technique should allow pharmacological manipulations of selective dopamine pathways in vitro and help in elucidating various factors responsible for differential regulation of populations of dopamine neurons.
Lee
T H
TH
Department of Psychiatry, Duke University Medical Center, Durham, NC 27710.
Ellinwood
E H
EH
Einstein
G
G
D000818:Animals; D003342:Corpus Striatum / Q000378:metabolism / Q000502:physiology; D004298:Dopamine / Q000378:metabolism*; D004594:Electrophysiology; D006651:Histocytochemistry; D066298:In Vitro Techniques; D008297:Male; D008839:Microelectrodes; D008863:Microspheres; D009434:Neural Pathways / Q000166:cytology / Q000502:physiology; D009474:Neurons / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013238:Stereotaxic Techniques; D013378:Substantia Nigra / Q000166:cytology / Q000502:physiology*
D004298:Dopamine