Suppression of glucocorticoid secretion enhances cholinergic transmission in rat hippocampus.
We previously demonstrated that suppression of glucocorticoid secretion by adrenalectomy (ADX) impaired prefrontal cortex-sensitive working memory, but not reference memory. Since the cholinergic system in the hippocampus is also involved in these memories, we examined the effects of glucocorticoid suppression on cholinergic transmission in the rat hippocampus. A microdialysis study revealed that ADX did not affect the basal acetylcholine release, but enhanced the KCl-evoked response. This enhanced response was reversed by the corticosterone replacement treatment. The extracellular choline concentrations increased under both basal and KCl-stimulated conditions in the ADX rats, and these increases were also reversed by the corticosterone replacement. These results indicate that suppression of glucocorticoid secretion enhances cholinergic transmission in the hippocampus in response to stimuli. It is possible that this enhanced cholinergic transmission may not contribute to the ADX-induced working memory impairment, but it may be involved in maintenance of reference memory.
Mizoguchi
Kazushige
K
Department of Geriatric Medicine, National Institute for Longevity Sciences, National Center for Geriatrics and Gerontology, 36-3 Gengo, Morioka, Obu, Aichi 474-8511, Japan. k-mizo@nils.go.jp
Shoji
Hirotaka
H
Ikeda
Ryuji
R
Tanaka
Yayoi
Y
Maruyama
Wakako
W
Tabira
Takeshi
T
D000109:Acetylcholine / Q000032:analysis / Q000378:metabolism*; D000315:Adrenalectomy / Q000379:methods; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology; D002794:Choline / Q000378:metabolism; D002799:Cholinergic Fibers / Q000187:drug effects / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003345:Corticosterone / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D005938:Glucocorticoids / Q000378:metabolism* / Q000502:physiology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007274:Injections, Intraperitoneal; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology; D017551:Microdialysis / Q000379:methods; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*
D000893:Anti-Inflammatory Agents; D005938:Glucocorticoids; D011189:Potassium Chloride; D002794:Choline; D000109:Acetylcholine; D003345:Corticosterone