Hypothalamic monoamines and their catabolites in relation to the estradiol-induced luteinizing hormone surge

Heinz H. Osterburg, Nancy A. Telford, David G. Morgan, Ilene Cohen-Becker, Phyllis M. Wise, Caleb E. Finch

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish (US)
Pages (from-to)31-40
Number of pages10
JournalBrain Research
Issue number1
StatePublished - Apr 14 1987
Externally publishedYes


  • 4-Hydroxy-3-methoxyphenylethyleneglycol (MHPG)
  • Electrochemical detection
  • Estradiol
  • High-performance liquid chromatography (HPLC)
  • Luteinizing hormone (LH) surge
  • Medial basal hypothalamus
  • Monoamine

ASJC Scopus subject areas

  • General Neuroscience
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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