Differential Expression of Estrogen Receptor &amp;agr; and &amp;bgr; Immunoreactivity by Oxytocin Neurons of Rat Paraventricular Nucleus

Simonian, Sharon X.; Herbison, Allan E.

doi:10.1046/j.1365-2826.1997.00659.x

Cited by 118 publications

(91 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Specifically, immunocytochemistry recognizes ERa in the pituitary and neurons in specific brain regions (Okamura et al 1992(Okamura et al , 1994. While it is known that ERb immunoreactivity is expressed in the PVN and the NTS (Simonian & Herbison 1997, Shughrue et al 1997, our previous reports have shown that 48-h fasting significantly increases ERa expression in these nuclei (Estacio et al 1996a, 1996b, Estacio et al 2004). To our knowledge, whether ERb expression is increased during fasting has not been elucidated.…”

Section: Discussionmentioning

confidence: 98%

Temporal expression of estrogen receptor α in the hypothalamus and medulla oblongata during fasting: a role of noradrenergic neurons

Reyes¹,

Tsukamura²,

I’Anson³

et al. 2006

Journal of Endocrinology

View full text Add to dashboard Cite

Fasting-induced LH suppression is augmented by estrogen in female rats. We investigated the temporal changes in the number of estrogen receptor a (ERa)-immunoreactive (ir) cells in various brain regions in ovariectomized rats fasted for 6, 24, 30, and 48 h, commencing at 1300 h. We also determined the anatomical relationship of ERa immunoreactivity and dopamine-b-hydroxylase (DBH) neurons in the A2 region of the nucleus of the solitary tract (NTS) and the paraventricular nucleus (PVN). The number of ERa-ir cells significantly increased after 30 h from the onset of fasting in the PVN and NTS compared with the unfasted controls and was sustained until 48 h. In the A2 region of 48-h fasted rats, 46$75% DBH-ir cells expressed ERa, and this was significantly higher than in unfasted controls (8$16% DBH-ir cells expressed ERa). In the PVN, most ERa-ir neurons were juxtaposed with DBH-ir varicosities. These results suggest that ERa is expressed in specific brain regions at a defined time from the onset of fasting. In addition, the anatomical relationship of noradrenergic and ERa-ir neurons in the A2 region and PVN may suggest a role for estrogen in increasing the activity of noradrenergic neurons in the A2 region and enhancing sensitivity of the PVN to noradrenergic input arising from the lower brainstem and thereby augmenting the suppression of LH secretion during fasting.

show abstract

Section: Discussionmentioning

confidence: 98%

Temporal expression of estrogen receptor α in the hypothalamus and medulla oblongata during fasting: a role of noradrenergic neurons

Reyes¹,

Tsukamura²,

I’Anson³

et al. 2006

Journal of Endocrinology

View full text Add to dashboard Cite

show abstract

“…The plasma levels of estradiol in rats that received estradiol injections in the current study correspond to physiological levels during late estrus and early diestrus [38, 39]. As both CRF and oxytocin neurons in the hypothalamic paraventricular nucleus have been reported to express estrogen receptor-beta [42, 57], the effects of estradiol on the 5-HT 1A receptor systems could be directly mediated by the transcriptional effects of these estrogen receptors inside CRF and oxytocin neurons in the paraventricular nucleus of the hypothalamus.…”

Section: Discussionmentioning

confidence: 99%

Ovariectomy-Induced Increases in Hypothalamic Serotonin-1A Receptor Function in Rats Are Prevented by Estradiol

Raap¹,

DonCarlos

García³

et al. 2002

Neuroendocrinology

View full text Add to dashboard Cite

The present study investigated the effects of long-term estradiol withdrawal (ovariectomy) on hypothalamic serotonin-1A (5-HT_1A) receptor signaling. Changes in neuroendocrine responses to the 5-HT_1A agonist 8-OH-DPAT and levels of G_z protein in the hypothalamus were used to examine 5-HT_1A receptor signaling. Five days following ovariectomy, rats received daily injections of either 2 µg of β-estradiol 3-benzoate or vehicle (subcutaneously) for 2, 4 or 14 days. Twenty-four hours after the last injection, and 15 min prior to sacrifice, rats were injected with (±)8-OH-DPAT (50 µg/kg, s.c.) or saline. Estradiol treatment did not alter basal corticotropin (ACTH) or oxytocin levels. Injection of (±)8-OH-DPAT produced significant increases in plasma ACTH and oxytocin levels. In the vehicle-treated rats, hormone responses to 8-OH-DPAT were enhanced in rats that received injections for 14 days compared with rats that received injections for either 2 or 4 days. Estradiol treatment for 4 or 14 days blunted this enhanced ACTH response to 8-OH-DPAT, whereas the oxytocin response to 8-OH-DPAT was only blunted after 14 daily injections of β-estradiol 3-benzoate. The treatment with β-estradiol 3-benzoate (2 µg/rat) did not reduce membrane-associated G_z protein levels in the paraventricular nucleus of the hypothalamus. Hence, the inhibitory influence of a low dose of β-estradiol 3-benzoate on 5-HT_1A receptor signaling in the hypothalamus is not accompanied by a change in the levels of G_z protein in the paraventricular hypothalamic nucleus. Results from the present study indicate a supersensitivity of 5-HT_1A receptors after withdrawal of estradiol and suggest that estradiol suppresses 5-HT_1A receptor signaling.

show abstract

“…Estrogen decreases the sensitivity of 5-HT 1A receptors in both the paraventricular [20] and the ventromedial nucleus of the hypothalamus [41, 42]. Neurons in the hypothalamic PVN predominantly express estrogen receptor-β (ER-β) but very little estrogen receptor-α(ER-α) [43,44,45,46]. In contrast, neurons in the MBH (ventromedial and arcuate nuclei) predominantly express ER-α [44,45,46,47].…”

Section: Introductionmentioning

confidence: 99%

“…Neurons in the hypothalamic PVN predominantly express estrogen receptor-β (ER-β) but very little estrogen receptor-α(ER-α) [43,44,45,46]. In contrast, neurons in the MBH (ventromedial and arcuate nuclei) predominantly express ER-α [44,45,46,47]. Therefore, a differential effect of estrogen treatment on the levels of Gα i , Gα o and Gα z protein in the PVN versus MBH could provide information on the relative contribution of ER-α and ER-β in mediating the effects of estrogen on 5-HT 1A receptor signaling.…”

Section: Introductionmentioning

confidence: 99%

Estrogen Reduces Serotonin-1A Receptor-Mediated Oxytocin Release and Gαi/o/z Proteins in the Hypothalamus of Ovariectomized Rats

D’Souza¹,

Zhang²,

Damjanoska³

et al. 2004

Neuroendocrinology

View full text Add to dashboard Cite

The present study examined the effect of estradiol on hypothalamic serotonin-1A (5-HT_1A) receptor signaling in female rats. We first examined the time-course effects of a single injection of the 5-HT_1A receptor agonist (±)8-OH-DPAT (5, 15 or 30 min prior to decapitation), and dose response of (+)8-OH-DPAT (50, 100, 200 or 500 µg/kg, s.c.) on plasma hormones in ovariectomized rats that received a daily injection of β-estradiol 3-benzoate (10 µg/day, s.c.) or vehicle (sesame oil) for 2 days. In vehicle- and estrogen-treated rats, the peak response of hormones occurred at 15 min after injection and the time-course of oxytocin and adrenocorticotropic hormone (ACTH) responses to an injection of 8-OH-DPAT were comparable. However, only the oxytocin response was reduced by estrogen treatment. A second experiment compared the ACTH and oxytocin responses with doses of 50 or 200 µg/kg, s.c. of (+)8-OH-DPAT vs. (±)8-OH-DPAT in ovariectomized rats that were treated with oil or β-estradiol 3-benzoate (10 µg/day, s.c.) for 2 days. (+)8-OH-DPAT and (±)8-OH-DPAT produced a similar magnitude of increase in plasma levels of ACTH and oxytocin. Treatment with β-estradiol 3-benzoate produced a significant and comparable reduction in the oxytocin response to the highest dose (200 µg/kg, s.c.) of both (+)8-OH-DPAT and (±)8-OH-DPAT but did not alter the ACTH response to either (+)8-OH-DPAT or (±)8-OH-DPAT. In the dose-response experiment, a dose of 50 µg/kg of (+)8-OH-DPAT produced a maximal increase in plasma levels of ACTH, while the maximal oxytocin response was achieved with a dose of 200 µg/kg, s.c. Treatment with β-estradiol 3-benzoate reduced the maximal oxytocin response to (+)8-OH-DPAT (by 29%) but did not alter the ACTH response to any doses of (+)8-OH-DPAT. To examine potential mechanisms mediating the effects of estrogen on 5-HT_1A receptor signaling, we measured the levels of Gα_i, Gα_oand Gα_zproteins, which couple 5-HT_1A receptors to their effector enzymes, in two subregions of the hypothalamus. The levels of Gα_z protein were reduced in the mediobasal hypothalamus (containing the ventromedial and arcuate nuclei), which mainly expresses estrogen receptor-α, but not in the paraventricular hypothalamus, which mainly expresses estrogen receptor-β. Estradiol reduced the levels of Gα_i2 and Gα_i3proteins in both hypothalamic regions but did not affect Gα_i1 levels in either area. Combined, the data suggest that racemic and stereoselective 8-OH-DPAT have similar neuroendocrine effects and that both estrogen receptor-α and estrogen receptor-β mediate the reduction in levels of Gα_i2,3 proteins.

show abstract

Differential Expression of Estrogen Receptor &agr; and &bgr; Immunoreactivity by Oxytocin Neurons of Rat Paraventricular Nucleus

Cited by 118 publications

References 10 publications

Temporal expression of estrogen receptor α in the hypothalamus and medulla oblongata during fasting: a role of noradrenergic neurons

Temporal expression of estrogen receptor α in the hypothalamus and medulla oblongata during fasting: a role of noradrenergic neurons

Ovariectomy-Induced Increases in Hypothalamic Serotonin-1A Receptor Function in Rats Are Prevented by Estradiol

Estrogen Reduces Serotonin-1A Receptor-Mediated Oxytocin Release and Gα<sub>i/o/z</sub> Proteins in the Hypothalamus of Ovariectomized Rats

Contact Info

Product

Resources

About