Estrogen induces a rapid increase in galanin levels in female rat hippocampal formation--possibly a nongenomic/indirect effect.
Administration of 17beta-estradiol to ovariectomized rats increased the concentrations of galanin-like immunoreactivity (LI) in the hippocampal formation by 215% (P < 0.001) within 1 h. An increase of 125% (P < 0.05) was observed in the same brain region in the proestrous phase of a normal estrous cycle. Tamoxifen did not block the 17beta-estradiol-induced increase in the concentration of galanin-LI but resulted in a 62% decrease in the hypothalamus within 1 h. In vivo microdialysis in the dorsal hippocampal formation showed a decrease of extracellular galanin-LI (P < 0.001) 1-2 h after treatment with 17beta-estradiol, indicating a decreased release of galanin. For comparison, we studied the concentrations of neuropeptide Y, which were not influenced significantly in any of the regions studied. Taken together our results suggest that 17beta-estradiol inhibits galanin release, presumably from noradrenergic nerve terminals, and primarily via a nongenomic/indirect action, not necessarily involving the classical nuclear receptors ER-alpha or ER-beta. These rapid estrogen-induced changes in galanin release could influence transmitter signalling and plasticity in the hippocampal formation.
Hilke
Susanne
S
Department of Biomedicine and Surgery, Division of Clinical Chemistry, Faculty of Health Sciences, University Hospital, SE-581 82 Linköping, Sweden. sushi@ibk.liu.se
Theodorsson
Annette
A
Fetissov
Serguei
S
Aman
Katarina
K
Holm
Lovisa
L
Hökfelt
Tomas
T
Theodorsson
Elvar
E
D000704:Analysis of Variance; D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004958:Estradiol / Q000097:blood / Q000494:pharmacology*; D030762:Estrous Cycle / Q000187:drug effects / Q000502:physiology; D005260:Female; D019004:Galanin / Q000378:metabolism*; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D017403:In Situ Hybridization / Q000379:methods; D017551:Microdialysis / Q000379:methods; D009478:Neuropeptide Y / Q000378:metabolism; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D009478:Neuropeptide Y; D004958:Estradiol; D019004:Galanin