TY - JOUR
T1 - Hypothalamic monoamines and their catabolites in relation to the estradiol-induced luteinizing hormone surge
AU - Osterburg, Heinz H.
AU - Telford, Nancy A.
AU - Morgan, David G.
AU - Cohen-Becker, Ilene
AU - Wise, Phyllis M.
AU - Finch, Caleb E.
N1 - Funding Information:
Diana Lerner tor expert assistance in typing th~s manuscript Medhat Gorgy gave valuable techmcal assistance The work was supported by AG-00446 to C E F, HD15955 and AG02224 to P M W P M W
PY - 1987/4/14
Y1 - 1987/4/14
N2 - Monoamines and non-conjugated catabolites (serotonin (5-HT), 5-hydroxyindole acetic acid (5-HIAA), 3,4-dihydroxyphenyl-acetic acid (DOPAC), homovanillic acid (HVA), 4-hydroxy-3-methoxyphenylethyleneglycol (MHPG), norepinephrine (NE), and dopamine (DA)) were measured in the medial basal hypothalamus (MBH) and preoptic area (POA) of ovariectomized (OVX) and OVX estradiol (E2)-treated rats using high-performance liquid chromatoggraphy with electrochemical detection. These E2 treatments were sufficient to induce and LH surge. The use of MHPG/NE ratios as estimates of NE release was validated in the rat hypothalamus by the major decreases of MHPG after injection of the α2-adrenergic agonist, clonidine, and by MHPG increases after the α2-antagonist, yohimbine. The ratio, MHPG/NE, decreased between morning and afternoon in the MBH but not in the POA; there were no differences between OVX and E2-treated rats. Previous studies using a variety of methods indicate that NE turnover increases during LH surges. The present data suggest that unconjugated MHPG is not a sensitive measure of NE release in the rat hypothalamus, but can detect the large changes produced by stimulating or inhibiting the α2-adrenergic autoreceptor. The ratios of DOPAC/DA and 5-HIAA/5-HT in the MBH decreased consistently between morning and afternoon in OVX rats, with or without E2 treatment. This suggests that the release of DA and 5-HT decreases during the day regardless of steroidal milieu.
AB - Monoamines and non-conjugated catabolites (serotonin (5-HT), 5-hydroxyindole acetic acid (5-HIAA), 3,4-dihydroxyphenyl-acetic acid (DOPAC), homovanillic acid (HVA), 4-hydroxy-3-methoxyphenylethyleneglycol (MHPG), norepinephrine (NE), and dopamine (DA)) were measured in the medial basal hypothalamus (MBH) and preoptic area (POA) of ovariectomized (OVX) and OVX estradiol (E2)-treated rats using high-performance liquid chromatoggraphy with electrochemical detection. These E2 treatments were sufficient to induce and LH surge. The use of MHPG/NE ratios as estimates of NE release was validated in the rat hypothalamus by the major decreases of MHPG after injection of the α2-adrenergic agonist, clonidine, and by MHPG increases after the α2-antagonist, yohimbine. The ratio, MHPG/NE, decreased between morning and afternoon in the MBH but not in the POA; there were no differences between OVX and E2-treated rats. Previous studies using a variety of methods indicate that NE turnover increases during LH surges. The present data suggest that unconjugated MHPG is not a sensitive measure of NE release in the rat hypothalamus, but can detect the large changes produced by stimulating or inhibiting the α2-adrenergic autoreceptor. The ratios of DOPAC/DA and 5-HIAA/5-HT in the MBH decreased consistently between morning and afternoon in OVX rats, with or without E2 treatment. This suggests that the release of DA and 5-HT decreases during the day regardless of steroidal milieu.
KW - 4-Hydroxy-3-methoxyphenylethyleneglycol (MHPG)
KW - Electrochemical detection
KW - Estradiol
KW - High-performance liquid chromatography (HPLC)
KW - Luteinizing hormone (LH) surge
KW - Medial basal hypothalamus
KW - Monoamine
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U2 - 10.1016/0006-8993(87)90738-4
DO - 10.1016/0006-8993(87)90738-4
M3 - Article
C2 - 3580869
AN - SCOPUS:0023259861
SN - 0006-8993
VL - 409
SP - 31
EP - 40
JO - Brain Research
JF - Brain Research
IS - 1
ER -