PMID- 1967162
OWN - NLM
STAT- MEDLINE
DCOM- 19900207
LR  - 20131121
IS  - 0013-7227 (Print)
IS  - 0013-7227 (Linking)
VI  - 126
IP  - 1
DP  - 1990 Jan
TI  - The preovulatory prolactin surge is prolonged by a progesterone-dependent 
      dopaminergic mechanism.
PG  - 246-52
AB  - The preovulatory PRL surge consists of a sharp peak, a prolonged plateau, and a 
      termination phase. This study examined the role of progesterone in maintaining 
      elevated PRL release during the plateau phase and its effect on dopaminergic (DA) 
      neuronal activity. Immature rats were injected with PMSG on day 28, and blood was 
      collected during the periovulatory period. Plasma estradiol levels were elevated 
      before and during the PRL peak and declined during the plateau. Plasma 
      progesterone levels were low before and during the peak, rose 4- to 5-fold during 
      the plateau, and decreased to basal levels at the termination phase. In a second 
      experiment rats were subjected to acute ovariectomy (OVEX) or sham surgery (SHAM) 
      just before the onset of the PRL surge. Some OVEX rats were either immediately 
      implanted with an estradiol-containing capsule or given three injections of 
      progesterone during the time of the plateau phase. Blood PRL levels in SHAM rats 
      showed the typical peak, plateau, and termination phases. The PRL peak was 
      evident, but the plateau was missing in OVEX rats with or without estradiol 
      treatment. Replacement with progesterone restored the plateau. In a third 
      experiment, the stalk-median eminence, posterior pituitary, and striatum were 
      removed during the time of the midplateau phase. Tyrosine hydroxylase activity 
      was determined in tissue homogenates by a coupled hydroxylation-decarboxylation 
      assay. Tyrosine hydroxylase activity in the stalk-median eminence of SHAM and 
      progesterone-treated OVEX rats was similar, but was significantly lower than that 
      in OVEX rats with or without estradiol. Tyrosine hydroxylase activity in the 
      posterior pituitary and striatum was unchanged. To assess the functional DA input 
      to the anterior pituitary, haloperidol, a DA antagonist, was injected during the 
      midplateau phase. It induced a 12- to 17-fold rise in plasma PRL in both 
      untreated and estradiol-treated OVEX rats, but failed to increase PRL above the 
      plateau levels in SHAM and progesterone-treated OVEX rats. We conclude that the 
      plateau phase of the preovulatory PRL surge is dependent on the concomitant rise 
      in progesterone. Progesterone probably acts by reducing the DA neuronal activity 
      in the SME, resulting in an absence of functional DA input to anterior pituitary 
      lactotrophs.
FAU - Arbogast, L A
AU  - Arbogast LA
AD  - Department of Physiology and Biophysics, Indiana University School of Medicine, 
      Indianapolis 46223.
FAU - Ben-Jonathan, N
AU  - Ben-Jonathan N
LA  - eng
GR  - HD-21135/HD/NICHD NIH HHS/United States
GR  - NS-13243/NS/NINDS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Endocrinology
JT  - Endocrinology
JID - 0375040
RN  - 4G7DS2Q64Y (Progesterone)
RN  - 4TI98Z838E (Estradiol)
RN  - 9002-62-4 (Prolactin)
RN  - EC 1.14.16.2 (Tyrosine 3-Monooxygenase)
RN  - VTD58H1Z2X (Dopamine)
SB  - IM
MH  - Animals
MH  - Biomechanical Phenomena
MH  - Dopamine/*physiology
MH  - Estradiol/blood
MH  - Female
MH  - Median Eminence/enzymology
MH  - Ovariectomy
MH  - Ovulation/*physiology
MH  - Pituitary Gland/enzymology
MH  - Pituitary Gland, Anterior/metabolism
MH  - Progesterone/blood/*physiology
MH  - Prolactin/blood/*metabolism
MH  - Rats
MH  - Rats, Inbred Strains
MH  - Time Factors
MH  - Tyrosine 3-Monooxygenase/metabolism
EDAT- 1990/01/01 00:00
MHDA- 1990/01/01 00:01
CRDT- 1990/01/01 00:00
PHST- 1990/01/01 00:00 [pubmed]
PHST- 1990/01/01 00:01 [medline]
PHST- 1990/01/01 00:00 [entrez]
AID - 10.1210/endo-126-1-246 [doi]
PST - ppublish
SO  - Endocrinology. 1990 Jan;126(1):246-52. doi: 10.1210/endo-126-1-246.