Long-Term Ovarian Hormone Deprivation Alters the Ability of Subsequent Oestradiol Replacement to Regulate Choline Acetyltransferase Protein Levels in the Hippocampus and Prefrontal Cortex of Middle-Aged Rats

The role of oestrogen replacement therapy in preventing or delaying age‐associated cognitive decline is controversial. Therapy success may critically depend on the time of treatment initiation following cessation of ovarian function. The present study aimed to assess, in middle‐aged rats, whether th...

Full description

Saved in:

Bibliographic Details
Published in:	Journal of neuroendocrinology Vol. 20; no. 8; pp. 1023 - 1027
Main Authors:	Bohacek, J., Bearl, A. M., Daniel, J. M.
Format:	Journal Article
Language:	English
Published:	Oxford, UK Blackwell Publishing Ltd 01-08-2008 Blackwell Science
Subjects:	acetylcholine Aging - metabolism Aging - physiology Animals Biological and medical sciences ChAT Choline O-Acetyltransferase - metabolism cholinergic Estradiol - pharmacology Estrogen Replacement Therapy - veterinary Female Fundamental and applied biological sciences. Psychology Gonadal Steroid Hormones - deficiency Gonadal Steroid Hormones - metabolism Gonadal Steroid Hormones - pharmacology Hippocampus - drug effects Hippocampus - enzymology Hippocampus - metabolism oestrogen ovariectomy Ovariectomy - rehabilitation Ovary - metabolism Prefrontal Cortex - drug effects Prefrontal Cortex - enzymology Prefrontal Cortex - metabolism Rats Rats, Long-Evans Time Factors Treatment Failure Vertebrates: endocrinology oestrogen Ovariectomy Rat Rodentia Central nervous system Estrogen Prefrontal cortex Estradiol Long term Ovarian hormone Protein Encephalon Vertebrata Mammalia Animal Choline cholinergic Neurotransmitter ChAT Acetylcholine Sex steroid hormone Hippocampus
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	The role of oestrogen replacement therapy in preventing or delaying age‐associated cognitive decline is controversial. Therapy success may critically depend on the time of treatment initiation following cessation of ovarian function. The present study aimed to assess, in middle‐aged rats, whether the ability of oestradiol to modulate the cholinergic system depends on the timing of treatment initiation following ovariectomy. Using western blotting, protein levels of choline acetyltransferase (ChAT) were measured in the hippocampus and prefrontal cortex (PFC), which are both important areas with respect to cognitive function. In an initial experiment, we established the effects of oestradiol delivered via implanted capsules on ChAT levels in the hippocampus and PFC of young adult animals. In a second experiment, we tested the ability of the same oestradiol treatment paradigm to affect ChAT protein in 15‐month‐old middle‐aged rats that had been ovariectomised either at the age of 10 months or at 15 months. In both experiments, rats were sacrificed 10 days after receiving implants and ChAT protein levels were measured. In both young adult and middle‐aged animals, oestradiol treatment initiated immediately after ovariectomy significantly increased ChAT levels in the hippocampus but not in the PFC compared to cholesterol control treatment. However, when oestradiol treatment was initiated 5 months after ovariectomy, it failed to significantly increase ChAT levels in the hippocampus, but did so in the PFC. These data indicate that, after prolonged ovarian hormone deprivation, the ability of subsequent oestradiol treatment to modulate ChAT protein levels is altered in a site‐specific manner.
Bibliography:	ArticleID:JNE1752 istex:1C289D2C767D9FC1FE34FB806DDAD07E200856C7 ark:/67375/WNG-CJXHXQ9X-8 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	0953-8194 1365-2826
DOI:	10.1111/j.1365-2826.2008.01752.x