title: Parvalbumin, calbindin, or calretinin in cortically projecting and GABAergic, cholinergic, or glutamatergic basal forebrain neurons of the rat.
abstract: The basal forebrain (BF) plays an important role in modulating cortical activity and facilitating processes of attention, learning, and memory. This role is subserved by cholinergic neurons but also requires the participation of other noncholinergic neurons. Noncholinergic neurons include gamma-amino butyric acidergic (GABAergic) neurons, some of which project in parallel with the cholinergic cells to the cerebral cortex, others of which project caudally or locally. With the original aim of distinguishing different subgroups of GABAergic neurons, we examined immunostaining for the calcium binding proteins (CBPs) parvalbumin (Parv), calbindin (Calb), and calretinin (Calret) in the rat. Although the CBP(+) cell groups were distributed in a coextensive manner with the GABAergic cells, they were collectively more numerous. Of cells retrogradely labeled with cholera toxin (CT) from the prefrontal or parietal cortex, Parv(+) and Calb(+) cells, but not Calret(+) cells, represented substantial proportions ( approximately 35-45% each) that collectively were greater than that of GABAergic projection neurons. From dual immunostaining for the CBPs and glutamic acid decarboxylase (GAD), it appeared that the vast majority (>90%) of the Parv(+) group was GAD(+), whereas only a small minority (<10%) of the Calb(+) or Calret(+) group was GAD(+). Significant proportions of Calb(+) (>40%) and Calret(+) (>80%) neurons were immunopositive for phosphate-activated glutaminase, the synthetic enzyme for transmitter glutamate. The results suggested that, whereas Calret(+) cells predominantly comprise caudally or locally projecting, possibly glutamatergic BF neurons, Parv(+) cells likely comprise the cortically projecting GABAergic BF neurons and Calb(+) cells the cortically projecting, possibly glutamatergic BF neurons that would collectively participate with the cholinergic cells in the modulation of cortical activity.
authors.affiliation: Dipartimento di Scienze Cliniche L. Sacco, Università degli Studi di Milano, 20157 Milan, Italy.
authors.forename: Ivana
authors.initials: I
authors.lastname: Gritti
authors.forename: Ian D
authors.initials: ID
authors.lastname: Manns
authors.forename: Lynda
authors.initials: L
authors.lastname: Mainville
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Jones
mesh_terms: D000109:Acetylcholine / Q000032:analysis; D000818:Animals; D064032:Calbindin 2; D064026:Calbindins; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000737:chemistry*; D002795:Choline O-Acetyltransferase / Q000032:analysis; D005455:Fluorescent Antibody Technique; D005968:Glutamate Decarboxylase / Q000032:analysis; D018698:Glutamic Acid / Q000032:analysis; D005972:Glutaminase / Q000032:analysis; D007124:Immunoenzyme Techniques; D007395:Interneurons / Q000737:chemistry; D008297:Male; D009434:Neural Pathways / Q000737:chemistry; D009474:Neurons / Q000737:chemistry*; D010296:Parietal Lobe / Q000737:chemistry; D010320:Parvalbumins / Q000032:analysis*; D017397:Prefrontal Cortex / Q000737:chemistry; D016548:Prosencephalon / Q000737:chemistry*; D051381:Rats; D017208:Rats, Wistar; D064030:S100 Calcium Binding Protein G / Q000032:analysis*; D005680:gamma-Aminobutyric Acid / Q000032:analysis
chemical_list: C576512:Calb2 protein, rat; D064032:Calbindin 2; D064026:Calbindins; D010320:Parvalbumins; D064030:S100 Calcium Binding Protein G; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D002795:Choline O-Acetyltransferase; D005972:Glutaminase; D005968:Glutamate Decarboxylase; D000109:Acetylcholine