PMID- 9688344
OWN - NLM
STAT- MEDLINE
DCOM- 19981009
LR  - 20190921
IS  - 0953-8194 (Print)
IS  - 0953-8194 (Linking)
VI  - 10
IP  - 6
DP  - 1998 Jun
TI  - Reduced noradrenergic tone to the hypothalamic paraventricular nucleus 
      contributes to the stress hyporesponsiveness of lactation.
PG  - 417-27
AB  - Lactation in mammals is accompanied by a marked decrease in stress responsiveness 
      that we previously attributed, in part, to a reduction in noradrenergic (NA) 
      innervation of hypothalamic paraventricular nucleus (PVN) neurons controlling 
      neuroendocrine stress responses. In the present study, we compared in-vivo PVN 
      catecholamine secretion by microdialysis between nonlactating and lactating 
      females and tested the effects of NA alpha-1 and alpha-2 receptor antagonists 
      (corynanthine and idazoxan, respectively) on the acute stress response of 
      lactating and virgin female rats. To determine if PVN alpha-adrenoreceptor 
      density, affinity, or synthesis, changes as a function of lactation, we performed 
      receptor autoradiography, Scatchard analysis and in situ hybridization of 
      alpha-adrenoreceptors. Densitometric analysis of the alpha-adrenoreceptors in the 
      supraoptic nucleus (SON) was used to evaluate changes in magnocellular neurons. 
      Endogenous PVN norepinephrine release under basal conditions was lower in 
      lactating females than in females who had their pups removed for 2 days, and 
      microdialysate concentrations of adrenaline and MHPG were attenuated in lactating 
      females. Alpha-2 adrenoreceptor density in the PVN showed a significant decrease 
      from lactation day 3 to lactation days 10-12 and a reduction to 40% of virgin 
      controls on days 10-20 of lactation. A similar pattern was observed for the SON. 
      The affinity of hypothalamic alpha-2 adrenoreceptors was reduced as a function of 
      lactation. Alpha-1 adrenoreceptor density in the PVN and in the hypothalamus rose 
      as a function of lactation, although the affinity of these receptors was not 
      altered. In contrast, alpha-1D adrenoreceptor subtype mRNA expression in the PVN 
      decreased in middle lactating females (day 10) compared to virgins. 
      Intracerebroventricular (i.c.v.) application of idazoxan, significantly increased 
      the ACTH response to swim stress in virgin females, but had the opposite effect 
      in lactating females. In contrast, i.c.v. corynanthine treatment significantly 
      decreased the ACTH response in virgins, but not in lactating females. Overall, 
      these data suggest that the secretion of NA in the PVN is reduced during 
      lactation, and that the ability of PVN parvocellular neurons to respond to 
      changes in synaptic NA levels (i.e. after stress) is also altered.
FAU - Toufexis, D J
AU  - Toufexis DJ
AD  - Douglas Hospital Research Center, Department of Psychiatry, Neurology & 
      Neurosurgery, McGill University, Montreal, Quebec, Canada.
FAU - Thrivikraman, K V
AU  - Thrivikraman KV
FAU - Plotsky, P M
AU  - Plotsky PM
FAU - Morilak, D A
AU  - Morilak DA
FAU - Huang, N
AU  - Huang N
FAU - Walker, C D
AU  - Walker CD
LA  - eng
GR  - MH53851/MH/NIMH NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - J Neuroendocrinol
JT  - Journal of neuroendocrinology
JID - 8913461
RN  - 0 (Adrenergic alpha-Antagonists)
RN  - 0 (Receptors, Adrenergic, alpha)
RN  - 534-82-7 (Methoxyhydroxyphenylglycol)
RN  - 9002-60-2 (Adrenocorticotropic Hormone)
RN  - X4W3ENH1CV (Norepinephrine)
RN  - YKH834O4BH (Epinephrine)
SB  - IM
MH  - Adrenergic alpha-Antagonists/pharmacology
MH  - Adrenocorticotropic Hormone/pharmacology
MH  - Animals
MH  - Down-Regulation
MH  - Epinephrine/metabolism
MH  - Female
MH  - *Lactation
MH  - Methoxyhydroxyphenylglycol/metabolism
MH  - Microdialysis
MH  - Norepinephrine/metabolism/*physiology
MH  - Paraventricular Hypothalamic Nucleus/drug effects/metabolism/*physiology
MH  - Pregnancy
MH  - Rats
MH  - Rats, Sprague-Dawley
MH  - Receptors, Adrenergic, alpha/classification
MH  - Stress, Physiological/*physiopathology
EDAT- 1998/08/04 00:00
MHDA- 1998/08/04 00:01
CRDT- 1998/08/04 00:00
PHST- 1998/08/04 00:00 [pubmed]
PHST- 1998/08/04 00:01 [medline]
PHST- 1998/08/04 00:00 [entrez]
AID - 10.1046/j.1365-2826.1998.00223.x [doi]
PST - ppublish
SO  - J Neuroendocrinol. 1998 Jun;10(6):417-27. doi: 10.1046/j.1365-2826.1998.00223.x.