TY - JOUR
T1 - Lactation decreases angiotensinogen mRNA expression in the midcaudal arcuate nucleus of the rat brain
AU - Speth, Robert C.
AU - Smith, M. Susan
AU - Grove, Kevin L.
PY - 2001
Y1 - 2001
N2 - In lactating rats, ANG II receptor binding in the arcuate nucleus (ARH) and median eminence is decreased. To further evaluate brain angiotensinergic activity during lactation, we assessed angiotensinogen (AON) mRNA by in situ hybridization in forebrains of day 10 or 11 postpartum lactating and diestrous rats. AON mRNA was abundantly expressed in the ARH, preoptic, suprachiasmatic, supraoptic, paraventricular, and dorsomedial hypothalamic nuclei, and other regions, similar to that reported in male rat brains. AON mRNA levels were decreased 27% in the midcaudal ARH of lactating rats but did not differ between lactating or diestrous rats in any of the other brain areas examined. Immunofluorescence for AON and glial fibrillary acidic protein or tyrosine hydroxylase confirmed that the AON immunoreactivity in the ARH was limited to astrocytes. Confocal microscopy revealed close appositions of AON-positive astrocytes to dopaminergic neurons in the ARH. The decrease in AON mRNA in the midcaudal ARH during lactation coupled with decreased ARH ANG II receptor binding suggests that lactating rats are less subject to ANG II-mediated inhibition of prolactin secretion.
AB - In lactating rats, ANG II receptor binding in the arcuate nucleus (ARH) and median eminence is decreased. To further evaluate brain angiotensinergic activity during lactation, we assessed angiotensinogen (AON) mRNA by in situ hybridization in forebrains of day 10 or 11 postpartum lactating and diestrous rats. AON mRNA was abundantly expressed in the ARH, preoptic, suprachiasmatic, supraoptic, paraventricular, and dorsomedial hypothalamic nuclei, and other regions, similar to that reported in male rat brains. AON mRNA levels were decreased 27% in the midcaudal ARH of lactating rats but did not differ between lactating or diestrous rats in any of the other brain areas examined. Immunofluorescence for AON and glial fibrillary acidic protein or tyrosine hydroxylase confirmed that the AON immunoreactivity in the ARH was limited to astrocytes. Confocal microscopy revealed close appositions of AON-positive astrocytes to dopaminergic neurons in the ARH. The decrease in AON mRNA in the midcaudal ARH during lactation coupled with decreased ARH ANG II receptor binding suggests that lactating rats are less subject to ANG II-mediated inhibition of prolactin secretion.
KW - Astrocytes
KW - Hypothalamus
KW - In situ hybridization histochemistry
KW - Prolactin secretion
KW - Tuberoinfundibular dopamine neurons
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U2 - 10.1152/ajpregu.2001.280.4.r1169
DO - 10.1152/ajpregu.2001.280.4.r1169
M3 - Article
C2 - 11247841
AN - SCOPUS:0034995857
SN - 0363-6119
VL - 280
SP - R1169-R1176
JO - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
JF - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
IS - 4 49-4
ER -