PMID- 3496207
OWN - NLM
STAT- MEDLINE
DCOM- 19870727
LR  - 20181130
IS  - 0013-7227 (Print)
IS  - 0013-7227 (Linking)
VI  - 121
IP  - 1
DP  - 1987 Jul
TI  - Posterior pituitary lobectomy abolishes the suckling-induced rise in prolactin 
      (PRL): evidence for a PRL-releasing factor in the posterior pituitary.
PG  - 205-11
AB  - The aim of this study was to determine the role of the posterior pituitary in the 
      regulation of PRL release during suckling. Lactating rats were subjected to 
      posterior pituitary lobectomy (LOBEX) or sham surgery (SHAM) and separation from 
      pups in the evening; experimental manipulations and blood collection were 
      performed the next morning. In the first experiment rats were divided into three 
      groups: SHAM, LOBEX, and LOBEX treated with a vasopressin analog, 
      1-desamino-8-D-arginine vasopressin and oxytocin. Plasma PRL levels in SHAM rats 
      increased 20- to 25-fold upon introduction of pups and remained elevated for the 
      duration of suckling. In contrast, basal plasma PRL levels in LOBEX rats were 3- 
      to 4-fold higher than in SHAM but suckling failed to induce a further increase. 
      Treatment of LOBEX rats with 1-desamino-8-D-arginine vasopressin and oxytocin 
      reduced water consumption and allowed for milk ejection and milk intake by the 
      pups but did not restore the suckling-induced rise in PRL. The second experiment 
      tested the functional integrity of the hypothalamic dopamine (DA) and 
      serotonergic systems after LOBEX and the ability of LOBEX-lactating rats to 
      respond to PRL-releasing stimuli other than suckling. Injections of 
      alpha-methyl-para tyrosine, an inhibitor of tyrosine hydroxylase, and 
      5-hydroxytryptophan, a precursor of serotonin, caused 20- to 30-fold rises in 
      plasma PRL levels in both LOBEX and SHAM rats. Exposure to ether elicited a 3- to 
      4-fold rise in PRL which was higher in magnitude and of longer duration in LOBEX 
      than in SHAM rats. CONCLUSIONS: Removal of the posterior pituitary from lactating 
      rats results in an increase in basal PRL levels and a complete abolishment of the 
      suckling-induced rise. Vasopressin and oxytocin restore water balance and milk 
      ejection in the LOBEX rat but fail to affect PRL secretion. The LOBEX-lactating 
      rat is not refractory to PRL-releasing stimuli other than suckling and its 
      hypothalamic DA and serotonergic systems are functionally intact. In addition to 
      DA, the posterior pituitary appears to contain a PRL-releasing factor(s) which 
      mediates the suckling-induced rise in PRL.
FAU - Murai, I
AU  - Murai I
FAU - Ben-Jonathan, N
AU  - Ben-Jonathan N
LA  - eng
GR  - NS 13234/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  - 0 (Methyltyrosines)
RN  - 333DO1RDJY (Serotonin)
RN  - 50-56-6 (Oxytocin)
RN  - 658-48-0 (alpha-Methyltyrosine)
RN  - 9002-62-4 (Prolactin)
RN  - C1LJO185Q9 (5-Hydroxytryptophan)
RN  - ENR1LLB0FP (Deamino Arginine Vasopressin)
RN  - VTD58H1Z2X (Dopamine)
SB  - IM
MH  - 5-Hydroxytryptophan/pharmacology
MH  - Animals
MH  - Deamino Arginine Vasopressin/pharmacology
MH  - Dopamine/physiology
MH  - Drinking/drug effects
MH  - Female
MH  - Hypothalamus/physiology
MH  - Lactation/drug effects/*physiology
MH  - Methyltyrosines/pharmacology
MH  - Milk Ejection/drug effects
MH  - Oxytocin/pharmacology
MH  - Pituitary Gland, Posterior/*physiology
MH  - Pregnancy
MH  - Prolactin/*metabolism
MH  - Rats
MH  - Rats, Inbred Strains
MH  - Serotonin/physiology
MH  - Stress, Physiological/physiopathology
MH  - alpha-Methyltyrosine
EDAT- 1987/07/01 00:00
MHDA- 1987/07/01 00:01
CRDT- 1987/07/01 00:00
PHST- 1987/07/01 00:00 [pubmed]
PHST- 1987/07/01 00:01 [medline]
PHST- 1987/07/01 00:00 [entrez]
AID - 10.1210/endo-121-1-205 [doi]
PST - ppublish
SO  - Endocrinology. 1987 Jul;121(1):205-11. doi: 10.1210/endo-121-1-205.