Neonatal estrogen decreases neural density of the septum-midbrain central gray connection underlying the lordosis-inhibiting system in female rats

Shinji Tsukahara, Naoki Ezawa, Korehito Yamanouchi

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Neurons in the lateral septum (LS) with projecting axons to the midbrain central gray (MCG) exert an inhibitory influence on lordosis. The number of such neurons is greater in female than in male rats. In this experiment, effects of neonatal estrogen on the density of the LS-MCG connections and on lordosis behavior were examined in female rats. On postnatal day 4 (day 0 = day of birth), females were injected subcutaneously with 50 or 100 μg estradiol benzoate (EB) or oil. On postnatal day 60, females and control males were gonadectomized. Behavioral tests were carried out after the implantation of silicone tubes containing estradiol. Lordotic activities in both males and EB-treated females were lower than in oil-treated females. After completing the behavioral tests, the animals were injected with Fluoro-Gold (FG), a retrograde tracer, into the right-side MCG and the number of FG-labeled neurons in the LS was measured. In all groups, the right-side LS ipsilateral to the FG injection had more FG-labeled neurons than the left-side LS. The number of FG-labeled neurons in the LS of oil-treated females was larger than that of males on both right and left sides. In the females treated with 100 μg EB (EB100), the number of FG-labeled neurons was comparable with that of males and lower than that of oil-treated females. The number of FG-labeled neurons in the EB50 females was also lower than that in oil-treated females, but tended to be larger than that observed in the EB100 group. These results indicate that neonatal estrogen decreases both lordotic activity and the density of the LS-MCG neural connections in female rats.

Original languageEnglish
Pages (from-to)226-233
Number of pages8
JournalNeuroendocrinology
Volume78
Issue number4
DOIs
Publication statusPublished - 2003

Fingerprint

Lordosis
Periaqueductal Gray
Estrogens
Neurons
Oils
Silicones
methanesulfonate salt 2-hydroxy-4,4'-diamidinostilbene
Axons
Estradiol

Keywords

  • Gonadal steroids
  • Lordosis
  • Midbrain central gray
  • Neonatal imprinting
  • Septum
  • Sex dimorphism

ASJC Scopus subject areas

  • Endocrinology
  • Neuroscience(all)

Cite this

Neonatal estrogen decreases neural density of the septum-midbrain central gray connection underlying the lordosis-inhibiting system in female rats. / Tsukahara, Shinji; Ezawa, Naoki; Yamanouchi, Korehito.

In: Neuroendocrinology, Vol. 78, No. 4, 2003, p. 226-233.

Research output: Contribution to journalArticle

@article{1153470f9002450da87243cf212e2210,
title = "Neonatal estrogen decreases neural density of the septum-midbrain central gray connection underlying the lordosis-inhibiting system in female rats",
abstract = "Neurons in the lateral septum (LS) with projecting axons to the midbrain central gray (MCG) exert an inhibitory influence on lordosis. The number of such neurons is greater in female than in male rats. In this experiment, effects of neonatal estrogen on the density of the LS-MCG connections and on lordosis behavior were examined in female rats. On postnatal day 4 (day 0 = day of birth), females were injected subcutaneously with 50 or 100 μg estradiol benzoate (EB) or oil. On postnatal day 60, females and control males were gonadectomized. Behavioral tests were carried out after the implantation of silicone tubes containing estradiol. Lordotic activities in both males and EB-treated females were lower than in oil-treated females. After completing the behavioral tests, the animals were injected with Fluoro-Gold (FG), a retrograde tracer, into the right-side MCG and the number of FG-labeled neurons in the LS was measured. In all groups, the right-side LS ipsilateral to the FG injection had more FG-labeled neurons than the left-side LS. The number of FG-labeled neurons in the LS of oil-treated females was larger than that of males on both right and left sides. In the females treated with 100 μg EB (EB100), the number of FG-labeled neurons was comparable with that of males and lower than that of oil-treated females. The number of FG-labeled neurons in the EB50 females was also lower than that in oil-treated females, but tended to be larger than that observed in the EB100 group. These results indicate that neonatal estrogen decreases both lordotic activity and the density of the LS-MCG neural connections in female rats.",
keywords = "Gonadal steroids, Lordosis, Midbrain central gray, Neonatal imprinting, Septum, Sex dimorphism",
author = "Shinji Tsukahara and Naoki Ezawa and Korehito Yamanouchi",
year = "2003",
doi = "10.1159/000073706",
language = "English",
volume = "78",
pages = "226--233",
journal = "Neuroendocrinology",
issn = "0028-3835",
publisher = "S. Karger AG",
number = "4",

}

TY - JOUR

T1 - Neonatal estrogen decreases neural density of the septum-midbrain central gray connection underlying the lordosis-inhibiting system in female rats

AU - Tsukahara, Shinji

AU - Ezawa, Naoki

AU - Yamanouchi, Korehito

PY - 2003

Y1 - 2003

N2 - Neurons in the lateral septum (LS) with projecting axons to the midbrain central gray (MCG) exert an inhibitory influence on lordosis. The number of such neurons is greater in female than in male rats. In this experiment, effects of neonatal estrogen on the density of the LS-MCG connections and on lordosis behavior were examined in female rats. On postnatal day 4 (day 0 = day of birth), females were injected subcutaneously with 50 or 100 μg estradiol benzoate (EB) or oil. On postnatal day 60, females and control males were gonadectomized. Behavioral tests were carried out after the implantation of silicone tubes containing estradiol. Lordotic activities in both males and EB-treated females were lower than in oil-treated females. After completing the behavioral tests, the animals were injected with Fluoro-Gold (FG), a retrograde tracer, into the right-side MCG and the number of FG-labeled neurons in the LS was measured. In all groups, the right-side LS ipsilateral to the FG injection had more FG-labeled neurons than the left-side LS. The number of FG-labeled neurons in the LS of oil-treated females was larger than that of males on both right and left sides. In the females treated with 100 μg EB (EB100), the number of FG-labeled neurons was comparable with that of males and lower than that of oil-treated females. The number of FG-labeled neurons in the EB50 females was also lower than that in oil-treated females, but tended to be larger than that observed in the EB100 group. These results indicate that neonatal estrogen decreases both lordotic activity and the density of the LS-MCG neural connections in female rats.

AB - Neurons in the lateral septum (LS) with projecting axons to the midbrain central gray (MCG) exert an inhibitory influence on lordosis. The number of such neurons is greater in female than in male rats. In this experiment, effects of neonatal estrogen on the density of the LS-MCG connections and on lordosis behavior were examined in female rats. On postnatal day 4 (day 0 = day of birth), females were injected subcutaneously with 50 or 100 μg estradiol benzoate (EB) or oil. On postnatal day 60, females and control males were gonadectomized. Behavioral tests were carried out after the implantation of silicone tubes containing estradiol. Lordotic activities in both males and EB-treated females were lower than in oil-treated females. After completing the behavioral tests, the animals were injected with Fluoro-Gold (FG), a retrograde tracer, into the right-side MCG and the number of FG-labeled neurons in the LS was measured. In all groups, the right-side LS ipsilateral to the FG injection had more FG-labeled neurons than the left-side LS. The number of FG-labeled neurons in the LS of oil-treated females was larger than that of males on both right and left sides. In the females treated with 100 μg EB (EB100), the number of FG-labeled neurons was comparable with that of males and lower than that of oil-treated females. The number of FG-labeled neurons in the EB50 females was also lower than that in oil-treated females, but tended to be larger than that observed in the EB100 group. These results indicate that neonatal estrogen decreases both lordotic activity and the density of the LS-MCG neural connections in female rats.

KW - Gonadal steroids

KW - Lordosis

KW - Midbrain central gray

KW - Neonatal imprinting

KW - Septum

KW - Sex dimorphism

UR - http://www.scopus.com/inward/record.url?scp=0242658437&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0242658437&partnerID=8YFLogxK

U2 - 10.1159/000073706

DO - 10.1159/000073706

M3 - Article

VL - 78

SP - 226

EP - 233

JO - Neuroendocrinology

JF - Neuroendocrinology

SN - 0028-3835

IS - 4

ER -