Expression and neuropeptidergic characterization of estrogen receptors (ER? and ER?) throughout the rat brain: Anatomical evidence of distinct roles of each subtype

Modulation by Estrogen-Receptor Directed Drugs of 5-Hydroxytryptamine-2A Receptors in Rat Brain

“…The ␤ form of the ER is generally less abundant and highly localized within the limbic system including the nucleus accumbens where an estrogenic effect was also observed and no ER ␣ mRNA was found. Thus, the comparison of our results with those of Laflamme et al (1998) suggests that the estrogenic effect on 5-HT 2A receptors would be mediated by the ER ␤, rather than ␣, the mRNA for which is present in the cortical regions as well as in the nucleus accumbens of the rat brain. No expression of the receptor ␣ and ␤ was found in the striatum.…”

“…Strongest hybridization signal of the 5-HT 2A receptor cRNA probe was found in cortical regions of the brain such as the frontal cortex that is the region where a strong estrogenic effect was observed. Little hybridization signal from the specific cRNA probe of the ER ␤ but no ER ␣ subtype was found in the frontal cortex (Laflamme et al 1998). The ␤ form of the ER is generally less abundant and highly localized within the limbic system including the nucleus accumbens where an estrogenic effect was also observed and no ER ␣ mRNA was found.…”

“…On the other hand, with newly designed ligands, specific conformation of the receptor-ligand complex will activate unique subsets of estrogen-responsive genes resulting in differential modulation and, ultimately, gene-and tissue-selective outcomes (Paige et al 1999). Interestingly, we have recently shown that estrogen regulates N-methyl-D-aspartate (NMDA) receptors with tissue selectivity; an increase has been observed in the hippocampus after estradiol treatment, whereas, a decrease was found in the frontal cortex (Cyr et al 2000), two rat brain areas expressing ER ␤ (Laflamme et al 1998).…”

Estrogen Receptor β, but not α, Mediates Estrogen's Effect on Cocaine-Induced Reinstatement of Extinguished Cocaine-Seeking Behavior in Ovariectomized Female Rats

“…However, the concentration and distribution of each receptor subtype within as well as outside these regions can vary greatly (Laflamme et al, 1998, reviewed by McEwen andAlves, 1999). It has been reported that ERb mRNA exists in brain regions where there is little or no ERa (eg, isocortex, cerebellum, ventral tegmental area (VTA)), and ERa can be found in other regions (eg, periaquaductal grey, arcuate nucleus, subfornical organ) that have little or no ERb (Kuiper et al, 1997;Shughrue et al, 1997;Laflamme et al, 1998). However, it should be noted that the relative abundance of ERa and ERb found in various brain regions can be ambiguous.…”

“…However, it should be noted that the relative abundance of ERa and ERb found in various brain regions can be ambiguous. For example, whereas a predominance of ERb mRNA has been consistently reported throughout the isocortex (Laflamme et al, 1998;Shughrue et al, 1997), there is conflict regarding which ER subtype predominates in the allocortex (Laflamme et al, 1998;Shughrue et al, 1997). Similarly, variable results have been found regarding ER localization in the substantia nigra, with some investigators finding more ERa than ERb mRNA in the pars compacta (Laflamme et al, 1998), and others reporting only weak staining for ERb mRNA in this region (Shughrue et al, 1997).…”