Parvalbumin-containing cells of the angular portion of the vertical limb terminate on calbindin-immunoreactive neurons located at the border between the lateral and medial septum of the rat

Jozsef Kiss, Zsolt Borhegyi, Agnes Csaky, Gabor Szeiffert, Csaba Leranth

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Abstract

In the septal complex, both parvalbumin and calbindin neurons cocontain GABA. In the same area, a large number of GABA-GABA synaptic connections can be observed. In order to further characterize their neurochemical nature, as well as the extrinsic and/or intrinsic origin of these GABA: terminals, the following experiments were performed: (1) correlated light- and electronmicroscopic double Immunostaining for calbindin and parvalbumin on septal sections of control rats; (2) light microscopic parvalbumin immunostaining of septal sections after surgical isolation (5 days) of the septum from its telencephalic or (3) hypothalamic afferents; and (4) parvalbumin immunostaining of sections prepared from the entire brain 2 days following horseradish peroxidase injection into the border between the lateral and medial septum. The results demonstrated that: (1) in a well-circumscribed, vertically longitudinal area located between the lateral and medial septum, 0.1-0.6 mm anterior to the bregma, a group of calbindin-containing, nonsomatospiny neurons are surrounded by parvalbumin-immunoreactive baskets; (2) these basket-forming axon terminals establish symmetric synaptic contacts with their targets; a and (3) their cells of origin are not in the medial septum, but in the angular portion of the vertical limb. These observations indicate that a portion of the septal complex GABA-GABA synaptic connections represent functional interaction between two different types of GABAergic neurons. The presynaptic GABAergic neurons contain parvalbumin, and the postsynaptic GABAergic cells are immunoreactive for calbindin. Furthermore, a population of the medial septum/diagonal band parvalbumin neurons project only to the hippocampus, while others, which may also send axons to the hippocampus, terminate on lateral septum calbindin cells as well.

Original languageEnglish
Pages (from-to)48-56
Number of pages9
JournalExperimental brain research
Volume113
Issue number1
DOIs
Publication statusPublished - Jan 30 1997

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Keywords

  • Diagonal band
  • Disinhibition
  • Double immunostaining
  • GABA
  • Rat
  • Retrograde tracing

ASJC Scopus subject areas

  • Neuroscience(all)

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