TY - JOUR
T1 - Regional differences in estradiol effects on numbers of HSD2-containing neurons in the nucleus of the solitary tract of rats
AU - Fan, Liming
AU - Smith, Courtney E.
AU - Curtis, Kathleen S.
N1 - Funding Information:
This research was supported by grants from the National Institute on Deafness and Communication Disorders ( DC-06360 ) and the Oklahoma Center for the Advancement of Science and Technology ( HR09-123S ). Preliminary versions of portions of these data were presented at the annual meetings of the Society for the Study of Ingestive Behaviors (Portland, OR; July, 2009) and of the Society for Neuroscience (Chicago, IL; October, 2009). We thank Ms. Jennifer Hackett and Ms. Minh Ngo for assistance with animal handling and analyses of uteri.
PY - 2010/10/28
Y1 - 2010/10/28
N2 - Estrogens affect body fluid balance, including sodium ingestion. Recent findings of a population of neurons in the hindbrain nucleus of the solitary tract (NTS) of rats that are activated during sodium need suggest a possible central substrate for this effect of estrogens. We used immunohistochemistry to label neurons in the NTS that express 11-β-hydroxysteroid dehydrogenase type 2 (HSD2), an enzyme that promotes aldosterone binding, in male rats, and in ovariectomized (OVX) rats given estradiol benzoate (EB) or oil vehicle (OIL). During baseline conditions, the number of HSD2 immunoreactive neurons in the NTS immediately rostral to the area postrema was greater in EB-treated OVX rats compared to those in OIL-treated OVX and male rats. A small number of HSD2 immunoreactive neurons was also labeled for dopamine-β-hydroxylase (DBH), an enzyme involved in norepinephrine biosynthesis. Double-labeled neurons in the NTS were located primarily in the more lateral portion of the HSD2 population, at the level of the area postrema in all three groups, with no sex or estrogen-mediated differences in the number of double-labeled neurons. These results suggest that two subpopulations of HSD2 neurons are present in the NTS. One subpopulation, which does not colocalize with DBH and is increased during conditions of elevated estradiol, may contribute to the effects of estrogens on sodium ingestion. The role of the other, smaller subpopulation, which colocalizes with DBH and is not affected by estradiol, remains to be determined, but one possibility is that these latter neurons are part of a larger network of catecholaminergic input to neuroendocrine neurons in the hypothalamus.
AB - Estrogens affect body fluid balance, including sodium ingestion. Recent findings of a population of neurons in the hindbrain nucleus of the solitary tract (NTS) of rats that are activated during sodium need suggest a possible central substrate for this effect of estrogens. We used immunohistochemistry to label neurons in the NTS that express 11-β-hydroxysteroid dehydrogenase type 2 (HSD2), an enzyme that promotes aldosterone binding, in male rats, and in ovariectomized (OVX) rats given estradiol benzoate (EB) or oil vehicle (OIL). During baseline conditions, the number of HSD2 immunoreactive neurons in the NTS immediately rostral to the area postrema was greater in EB-treated OVX rats compared to those in OIL-treated OVX and male rats. A small number of HSD2 immunoreactive neurons was also labeled for dopamine-β-hydroxylase (DBH), an enzyme involved in norepinephrine biosynthesis. Double-labeled neurons in the NTS were located primarily in the more lateral portion of the HSD2 population, at the level of the area postrema in all three groups, with no sex or estrogen-mediated differences in the number of double-labeled neurons. These results suggest that two subpopulations of HSD2 neurons are present in the NTS. One subpopulation, which does not colocalize with DBH and is increased during conditions of elevated estradiol, may contribute to the effects of estrogens on sodium ingestion. The role of the other, smaller subpopulation, which colocalizes with DBH and is not affected by estradiol, remains to be determined, but one possibility is that these latter neurons are part of a larger network of catecholaminergic input to neuroendocrine neurons in the hypothalamus.
KW - Dopamine-β-hydroxylase
KW - Ovariectomy
KW - Salt intake
KW - Sex difference
UR - http://www.scopus.com/inward/record.url?scp=77957373551&partnerID=8YFLogxK
U2 - 10.1016/j.brainres.2010.08.037
DO - 10.1016/j.brainres.2010.08.037
M3 - Article
C2 - 20728435
AN - SCOPUS:77957373551
SN - 0006-8993
VL - 1358
SP - 89
EP - 101
JO - Brain Research
JF - Brain Research
ER -