Hypothalamic and amygdaloid corticotropin-releasing hormone (CRH) and CRH receptor-1 mRNA expression in the stress-hyporesponsive late pregnant and early lactating rat
Apc. Da Costa et al., Hypothalamic and amygdaloid corticotropin-releasing hormone (CRH) and CRH receptor-1 mRNA expression in the stress-hyporesponsive late pregnant and early lactating rat, MOL BRAIN R, 91(1-2), 2001, pp. 119-130
This study investigated the expression of corticotropin releasing hormone (
CRH) and its receptor CRHR-1, and arginine vasopressin (AVP) mRNAs during t
he stress hyporesponsive periods of late pregnancy and lactation (day-3) an
d in virgin stress-responsive females. In situ hybridization histochemistry
showed that basal CRH mRNA in the paraventricular nucleus (PVN) decreased
in pregnant and increased in lactating rats (compared with virgin controls)
, whereas it increased after restraint stress only in virgin rats. Basal PV
N CRHR-1 mRNA increased markedly in all groups but reached lower levels in
pregnant rats. Basal AVP mRNA in the parvocellular PVN was higher in lactat
ing rats, and in contrast to CRH mRNA, it increased after stress in all gro
ups. In medial preoptic area (MPOA) CRH mRNA levels were higher in lactatin
g females compared with virgin and pregnant rats, and unexpectedly they dec
reased markedly after stress only in virgin rats. CRH mRNA levels in the ce
ntral and medial nuclei of the amygdala were higher in lactating rats than
in virgin or pregnant ones, and stress had no effect in either group. These
data suggest that these stress hyporesponsive periods: (1)do not depend on
basal CRH mRNA expression in the PVN; (2) appear to have intact stress-act
ivated afferent pathways to the PVN, as shown by preservation of CRHR-1 and
AVP responses to stress, but the information may be differently processed;
(3) are associated with an alteration in a CRH mediated pathway from the M
POA. (C) 2001 Published by Elsevier Science B.V.