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Estrogen treatment suppresses forebrain p75 neurotrophin receptor expression in aged, noncycling female rats
Author(s) -
Ping Sophie E.,
Greferath Ursula,
Barrett Graham L.
Publication year - 2002
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.10273
Subject(s) - basal forebrain , choline acetyltransferase , medicine , endocrinology , cholinergic neuron , neurotrophin , estrogen , low affinity nerve growth factor receptor , cholinergic , forebrain , nerve growth factor , biology , estrogen receptor , basal (medicine) , receptor , central nervous system , cancer , breast cancer , insulin
There is increasing evidence that estrogen has beneficial effects on cognition, both in humans and in rodents, and may delay Alzheimer's disease onset in postmenopausal women. Several rodent studies have utilised the ovariectomy model to show estrogen regulation of the p75 neurotrophin receptor, TrkA, and markers of acetylcholine synthesis in the cholinergic basal forebrain. We studied estrogenic effects in aged (16–17‐month‐old), noncycling rats. Estrogen treatment for 10 days drastically reduced p75 NTR immunoreactivity in the rostral parts of the basal forebrain. The number of p75 NTR ‐immunoreactive neurons was decreased, and those neurons remaining positive for p75 NTR showed reduced p75 NTR staining intensity. In vehicle‐treated rats, almost all choline acetyltransferase‐immunoreactive neurons were p75 NTR positive (and vice versa), but, in estrogen treated rats, large numbers of choline acetyltransferase‐immunoreactive cells were negative for p75 NTR . Similar levels of p75 NTR down‐regulation in the rostral basal forebrain were found when estrogen treatment was extended to 6 weeks. There was no reduction in the number of p75 NTR ‐immunoreactive neurons in the caudal basal forebrain after 10 days of treatment. After 6 weeks of treatment, however, there was evidence of p75 NTR down‐regulation in the caudal basal forebrain. There was no evidence of hypertrophy or atrophy of cholinergic neurons even after 6 weeks of estrogen treatment. Considering the evidence for the role of p75 NTR in regulating survival, growth and nerve growth factor responsiveness of cholinergic basal forebrain neurons, the results indicate an important aspect of estrogen's effects on the nervous system. © 2002 Wiley‐Liss, Inc.