PMID- 10433997
OWN - NLM
STAT- MEDLINE
DCOM- 19991021
LR  - 20190614
IS  - 0006-8993 (Print)
IS  - 0006-8993 (Linking)
VI  - 837
IP  - 1-2
DP  - 1999 Aug 7
TI  - Rhythmicity of beta-endorphinergic neuronal activity in the mediobasal 
      hypothalamus during pregnancy in the rat.
PG  - 152-60
AB  - During the first half of gestation in the rat, prolactin (PRL) from the anterior 
      pituitary gland exerts its luteotropic function on the ovary to stimulate 
      progesterone secretion. During this period, beta-endorphin stimulates PRL 
      secretion by regulation of dopaminergic neurons in the hypothalamus. During the 
      second half, placental lactogens (PLs) take the place of PRL in maintenance of 
      pregnancy, and initiate a negative feedback to suppress PRL secretion. However, 
      the effect of PLs on beta-endorphinergic neurons is not known. The aim of this 
      study was to examine the possibility that PLs suppress PRL secretion by 
      inhibiting beta-endorphinergic neuronal activity. To accomplish this aim, we 
      examined the changes in the neuronal activity of beta-endorphinergic neurons in 
      the mediobasal hypothalamus, as measured by Fos immunoreactivity, after 
      manipulating the levels of PRL and PLs during pregnancy. On day 4 of pregnancy, 
      animals received either Rcho-1 cells in the lateral ventricle that secrete PLs or 
      HRP-1 cells as controls. In a separate experiment on day 12, hysterectomy was 
      performed to remove the intrinsic source of PLs. These rats received Rcho-1 
      cells, HRP-1 cells, or nothing. Intracerebroventricular (i.c.v.) injection of 
      Rcho-1 into hysterectomized rats was done to examine the effect of PL 
      replacement. Sham-hysterectomy was also performed as a control. Animals were 
      sacrificed 2 days after each treatment at 0200 h, 1400 h, and 1800 h. Brains were 
      used for dual immunocytochemistry of Fos/beta-endorphin. The neuronal activity of 
      beta-endorphinergic neurons of HRP-1 i.c.v. injected animals showed a daily 
      rhythm, with high levels at 0200 h and 1800 h, and a low level at 1400 h. These 
      animals also exhibited two surges of PRL secretion on day 6 of pregnancy. This 
      rhythmicity of beta-endorphinergic neurons was also observed in Rcho-1 i.c.v. 
      injected animals, which showed very low and unchanging PRL levels. However, the 
      magnitude of neuronal activity was reduced. On day 14 of pregnancy, all four 
      experimental groups showed diurnal rhythms of beta-endorphinergic neurons. This 
      rhythmicity occurred even though PRL was elevated at all three time points in the 
      hysterectomized rats and very low in the Rcho-1 i.c.v. injected hysterectomized 
      and sham-hysterectomized rats. Our results demonstrate that there is a diurnal 
      rhythm of beta-endorphinergic neuronal activity in the mediobasal hypothalamus 
      during pregnancy in the rat. PLs might reduce the neuronal activity of 
      beta-endorphinergic neurons, but only during the first half of pregnancy, 
      partially explaining the suppression of PRL surges.
CI  - Copyright 1999 Elsevier Science B.V.
FAU - Lee, Y
AU  - Lee Y
AD  - Department of Molecular and Integrative Physiology, University of Kansas Medical 
      Center, 3901 Rainbow Boulevard, Kansas City, KS 66160-7401, USA.
FAU - Voogt, J L
AU  - Voogt JL
LA  - eng
GR  - HD-24190/HD/NICHD NIH HHS/United States
GR  - HD-33994/HD/NICHD NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - Netherlands
TA  - Brain Res
JT  - Brain research
JID - 0045503
RN  - 0 (Proto-Oncogene Proteins c-fos)
RN  - 60617-12-1 (beta-Endorphin)
RN  - 9002-62-4 (Prolactin)
SB  - IM
MH  - Analysis of Variance
MH  - Animals
MH  - Cells, Cultured
MH  - Choriocarcinoma/physiopathology
MH  - Female
MH  - Hypothalamus, Middle/*physiology
MH  - Male
MH  - Neoplasm Transplantation
MH  - Neurons/*physiology
MH  - Pregnancy
MH  - Pregnancy, Animal/*physiology
MH  - Prolactin/blood/*metabolism
MH  - Proto-Oncogene Proteins c-fos/analysis
MH  - Rats
MH  - Rats, Sprague-Dawley
MH  - Tumor Cells, Cultured
MH  - Uterine Neoplasms/physiopathology
MH  - beta-Endorphin/*physiology
EDAT- 1999/08/06 00:00
MHDA- 1999/08/06 00:01
CRDT- 1999/08/06 00:00
PHST- 1999/08/06 00:00 [pubmed]
PHST- 1999/08/06 00:01 [medline]
PHST- 1999/08/06 00:00 [entrez]
AID - S0006-8993(99)01603-0 [pii]
AID - 10.1016/s0006-8993(99)01603-0 [doi]
PST - ppublish
SO  - Brain Res. 1999 Aug 7;837(1-2):152-60. doi: 10.1016/s0006-8993(99)01603-0.