Calbindin-D 28kD immunofluorescence in ventral mesencephalic neurons labeled following injections of Fluoro-Gold in nucleus accumbens subterritories:inverse relationship relative to known neurotoxin vulnerabilities

The shell and core of the nucleus accumbens exhibit different vulnerabiliti es to neurotoxins. Calcium binding proteins are reported to offer some neur oprotection against excitotoxicity by suppressing or buffering intracellula r calcium. Differences in the distributions of the calbindin-D 28kD (CB) an d calretinin (CR) might be related to the different vulnerabilities to neur otoxins of dopaminergic neurons in the ventral mesencephalon that project t o the core and medial shell of the nucleus accumbens. To address this possi bility, Fluoro-Gold (FG) was injected into accumbens subterritories and num bers of retrogradely labeled neurons in the ventral tegmental area containi ng CB and CR immunoreactivities (ir) were expressed as a percentage of tota l numbers of labeled neurons. The perikaryal diameters and lengths of the i mmunoreactive dendrites of FG labeled neurons were also measured. About 70% and 35% of retrogradely labeled cells observed following core and medial s hell injections, respectively, exhibited CB immunoreactivity. Differences w ere not observed in the percentages of FG labeled cells exhibiting CR immun oreactivity following medial shell (13%) and core (15%) injections. The mea n perikaryal diameters and median summed lengths of dendrites of retrograde ly labeled neurons containing CB were smaller than in labeled neurons lacki ng CB following injections in both core and medial shell of the nucleus acc umbens. The data indicate that the different 6-hydroxydopamine (6-OHDA) vul nerabilities of ventral mesencephalic dopaminergic neurons are not obviousl y related to the presence of CB and CR. (C) 1999 Published by Elsevier Scie nce B.V. All rights reserved.