GABAergic septohippocampal neurons are not necessary for spatial memory

Kevin Pang, Romy Nocera, Adam J. Secor, Ryan M. Yoder

Research output: Contribution to journalArticle

69 Citations (Scopus)

Abstract

The medial septum/vertical limb of the diagonal band of Broca (MSDB) provides a major input to the hippocampus and is important for spatial memory. Both cholinergic and GABAergic MSDB neurons project to the hippocampus, and nonselective lesions of the MSDB or transections of the septohippocampal pathway impair spatial memory. However, selective lesions of cholinergic MSDB neurons using 192-IgG saporin (SAP) do not impair or only mildly impair spatial memory. Previously, intraseptal kainic acid was found to reduce levels of glutamic acid decarboxylase, a marker of GABAergic neurons, but not to alter the levels of choline acetyltransferase, a marker of cholinergic neurons. The present study further characterized the effects of kainic acid on GABAergic MSDB neurons and examined the effects of intraseptal kainic acid on spatial memory. Saline, kainic acid, SAP, or the combination of kainic acid and SAP was administered into the MSDB of rats. Spatial memory was assessed in an eight-arm radial maze and a water maze. Kainic acid destroyed GABAergic septohippocampal neurons, but spared cholinergic neurons. SAP eliminated MSDB cholinergic neurons, sparing noncholinergic neurons. Coadministration of kainic acid and SAP destroyed GABAergic and cholinergic MSDB neurons. Acquisition of the radial maze task and performance on this task with 4-h delays were unimpaired by intraseptal kainic acid or SAP, but were impaired by coadministration of kainic acid and SAP. Acquisition of the water maze task was unaffected by intraseptal kainic acid, delayed slightly by SAP, and impaired severely by coadministration of kainic acid and SAP. These results provide evidence that kainic acid at appropriate concentrations effectively destroys GABAergic septohippocampal neurons, while sparing cholinergic MSDB neurons. Furthermore, lesions of the GABAergic septohippocampal neurons do not impair spatial memory. While lesions of cholinergic MSDB neurons may mildly impair spatial memory, the combined lesion of GABAergic and cholinergic septohippocampal neurons resulted in a memory impairment that was greater than that observed after a selective lesion to either population. Thus, damage of GABAergic or cholinergic MSDB neurons, which together comprise the majority of the septohippocampal pathway, cannot totally account for the spatial memory impairment that is observed after nonselective lesions of the MSDB.

Original languageEnglish (US)
Pages (from-to)814-827
Number of pages14
JournalHippocampus
Volume11
Issue number6
DOIs
StatePublished - Dec 1 2001
Externally publishedYes

Fingerprint

GABAergic Neurons
Kainic Acid
Cholinergic Neurons
Spatial Memory
Hippocampus
Diagonal Band of Broca
Glutamate Decarboxylase
Choline O-Acetyltransferase
saporin
Water
Task Performance and Analysis
Cholinergic Agents
Arm
Extremities

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

Cite this

Pang, Kevin ; Nocera, Romy ; Secor, Adam J. ; Yoder, Ryan M. / GABAergic septohippocampal neurons are not necessary for spatial memory. In: Hippocampus. 2001 ; Vol. 11, No. 6. pp. 814-827.
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GABAergic septohippocampal neurons are not necessary for spatial memory. / Pang, Kevin; Nocera, Romy; Secor, Adam J.; Yoder, Ryan M.

In: Hippocampus, Vol. 11, No. 6, 01.12.2001, p. 814-827.

Research output: Contribution to journalArticle

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