Catecholamine turnover rates in discrete hypothalamic areas and associated changes in median eminence luteinizing hormone-releasing hormone and serum gonadotropins on proestrus and diestrous day 1

Naomi E Rance, P. M. Wise, M. K. Selmanoff, C. A. Barraclough

Research output: Contribution to journalArticle

186 Citations (Scopus)

Abstract

We have correlated catecholamine [CA; i.e. norepinephrine (NE), dopamine (DA), and epinephrine (E)] turnover rates in discrete hypothalamic nuclei and in the median eminence (ME) with concentration changes in ME LHRH and serum LH, FSH, PRL, estradiol, and progesterone levels at various times during proestrus and diestrous day 1 in 4-day cyclic rats. CA concentrations were measured with a radioenzymatic assay at 0, 60, and 120 min after ip injection of 400 mg/kg α-methyl-p-tyrosine, and rate constants and turnover rates were calculated. In a separate assay NE, DA, and E were separated by two-dimensional thin layer chromatography, and concentrations and turnover rates of CAs were calculated. The microdissected hypothalamic nuclei examined for NE turnover rates included the medial preoptic nucleus (MPN), suprachiasmatic nucleus (SCN), arcuate nucleus (AN), and ME. DA turnover rates also were measured in the MPN, ME, and AN. ME LHRH and serum hormone concentrations were measured by RIA. Between 0900-1 200 h, proestrous serum estradiol was elevated, but other serum hormones were basal, and CA turnover rates in the brain were low. However, ME LHRH concentrations increased significantly between 0900-1200 h on proestrus. Between 1200-1500 h, serum LH, FSH, PRL, and progesterone levels increased and ME LHRH levels declined significantly; during this time interval (1200-1400 h), a significant rise in ME NE and DA turnover rates occurred. Between 1500-1700 h on proestrus, while serum gonadotropins were still rising toward peak concentrations, increased ME NE turnover rates were maintained, but increased NE turnover rates also were evident in MPN, SCN, and AN. During this same time interval (1500-1700 h), a marked decline in ME and AN DA turnover rates occurred, although such rates remained unchanged within the MPN. There were no corresponding changes in MPN E turnover rates at any of the time intervals studied. The increased turnover rates of ME NE coupled with the concomitant decline in ME LHRH levels and the rise in plasma LH and FSH levels suggest that increased NE release may be important in initiating preovulatory LH and FSH surges. These changes in brain neurotransmitters and serum hormones are not the result of a diurnal rhythm, since corresponding changes in CA turnover rates or serum gonadotropins did not occur between (0900-1100 h and 1500-1700 h diestrous day 1.

Original languageEnglish (US)
Pages (from-to)1795-1802
Number of pages8
JournalEndocrinology
Volume108
Issue number5
StatePublished - 1981
Externally publishedYes

Fingerprint

Proestrus
Median Eminence
Gonadotropins
Gonadotropin-Releasing Hormone
Catecholamines
Norepinephrine
Serum
Preoptic Area
Arcuate Nucleus of Hypothalamus
Dopamine
Suprachiasmatic Nucleus
Hormones
Progesterone
Estradiol
Brain
Thin Layer Chromatography
Circadian Rhythm
Epinephrine
Neurotransmitter Agents
Tyrosine

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

@article{2c5eaef0954e4576a0a2c8e2a1d78d79,
title = "Catecholamine turnover rates in discrete hypothalamic areas and associated changes in median eminence luteinizing hormone-releasing hormone and serum gonadotropins on proestrus and diestrous day 1",
abstract = "We have correlated catecholamine [CA; i.e. norepinephrine (NE), dopamine (DA), and epinephrine (E)] turnover rates in discrete hypothalamic nuclei and in the median eminence (ME) with concentration changes in ME LHRH and serum LH, FSH, PRL, estradiol, and progesterone levels at various times during proestrus and diestrous day 1 in 4-day cyclic rats. CA concentrations were measured with a radioenzymatic assay at 0, 60, and 120 min after ip injection of 400 mg/kg α-methyl-p-tyrosine, and rate constants and turnover rates were calculated. In a separate assay NE, DA, and E were separated by two-dimensional thin layer chromatography, and concentrations and turnover rates of CAs were calculated. The microdissected hypothalamic nuclei examined for NE turnover rates included the medial preoptic nucleus (MPN), suprachiasmatic nucleus (SCN), arcuate nucleus (AN), and ME. DA turnover rates also were measured in the MPN, ME, and AN. ME LHRH and serum hormone concentrations were measured by RIA. Between 0900-1 200 h, proestrous serum estradiol was elevated, but other serum hormones were basal, and CA turnover rates in the brain were low. However, ME LHRH concentrations increased significantly between 0900-1200 h on proestrus. Between 1200-1500 h, serum LH, FSH, PRL, and progesterone levels increased and ME LHRH levels declined significantly; during this time interval (1200-1400 h), a significant rise in ME NE and DA turnover rates occurred. Between 1500-1700 h on proestrus, while serum gonadotropins were still rising toward peak concentrations, increased ME NE turnover rates were maintained, but increased NE turnover rates also were evident in MPN, SCN, and AN. During this same time interval (1500-1700 h), a marked decline in ME and AN DA turnover rates occurred, although such rates remained unchanged within the MPN. There were no corresponding changes in MPN E turnover rates at any of the time intervals studied. The increased turnover rates of ME NE coupled with the concomitant decline in ME LHRH levels and the rise in plasma LH and FSH levels suggest that increased NE release may be important in initiating preovulatory LH and FSH surges. These changes in brain neurotransmitters and serum hormones are not the result of a diurnal rhythm, since corresponding changes in CA turnover rates or serum gonadotropins did not occur between (0900-1100 h and 1500-1700 h diestrous day 1.",
author = "Rance, {Naomi E} and Wise, {P. M.} and Selmanoff, {M. K.} and Barraclough, {C. A.}",
year = "1981",
language = "English (US)",
volume = "108",
pages = "1795--1802",
journal = "Endocrinology",
issn = "0013-7227",
publisher = "The Endocrine Society",
number = "5",

}

TY - JOUR

T1 - Catecholamine turnover rates in discrete hypothalamic areas and associated changes in median eminence luteinizing hormone-releasing hormone and serum gonadotropins on proestrus and diestrous day 1

AU - Rance, Naomi E

AU - Wise, P. M.

AU - Selmanoff, M. K.

AU - Barraclough, C. A.

PY - 1981

Y1 - 1981

N2 - We have correlated catecholamine [CA; i.e. norepinephrine (NE), dopamine (DA), and epinephrine (E)] turnover rates in discrete hypothalamic nuclei and in the median eminence (ME) with concentration changes in ME LHRH and serum LH, FSH, PRL, estradiol, and progesterone levels at various times during proestrus and diestrous day 1 in 4-day cyclic rats. CA concentrations were measured with a radioenzymatic assay at 0, 60, and 120 min after ip injection of 400 mg/kg α-methyl-p-tyrosine, and rate constants and turnover rates were calculated. In a separate assay NE, DA, and E were separated by two-dimensional thin layer chromatography, and concentrations and turnover rates of CAs were calculated. The microdissected hypothalamic nuclei examined for NE turnover rates included the medial preoptic nucleus (MPN), suprachiasmatic nucleus (SCN), arcuate nucleus (AN), and ME. DA turnover rates also were measured in the MPN, ME, and AN. ME LHRH and serum hormone concentrations were measured by RIA. Between 0900-1 200 h, proestrous serum estradiol was elevated, but other serum hormones were basal, and CA turnover rates in the brain were low. However, ME LHRH concentrations increased significantly between 0900-1200 h on proestrus. Between 1200-1500 h, serum LH, FSH, PRL, and progesterone levels increased and ME LHRH levels declined significantly; during this time interval (1200-1400 h), a significant rise in ME NE and DA turnover rates occurred. Between 1500-1700 h on proestrus, while serum gonadotropins were still rising toward peak concentrations, increased ME NE turnover rates were maintained, but increased NE turnover rates also were evident in MPN, SCN, and AN. During this same time interval (1500-1700 h), a marked decline in ME and AN DA turnover rates occurred, although such rates remained unchanged within the MPN. There were no corresponding changes in MPN E turnover rates at any of the time intervals studied. The increased turnover rates of ME NE coupled with the concomitant decline in ME LHRH levels and the rise in plasma LH and FSH levels suggest that increased NE release may be important in initiating preovulatory LH and FSH surges. These changes in brain neurotransmitters and serum hormones are not the result of a diurnal rhythm, since corresponding changes in CA turnover rates or serum gonadotropins did not occur between (0900-1100 h and 1500-1700 h diestrous day 1.

AB - We have correlated catecholamine [CA; i.e. norepinephrine (NE), dopamine (DA), and epinephrine (E)] turnover rates in discrete hypothalamic nuclei and in the median eminence (ME) with concentration changes in ME LHRH and serum LH, FSH, PRL, estradiol, and progesterone levels at various times during proestrus and diestrous day 1 in 4-day cyclic rats. CA concentrations were measured with a radioenzymatic assay at 0, 60, and 120 min after ip injection of 400 mg/kg α-methyl-p-tyrosine, and rate constants and turnover rates were calculated. In a separate assay NE, DA, and E were separated by two-dimensional thin layer chromatography, and concentrations and turnover rates of CAs were calculated. The microdissected hypothalamic nuclei examined for NE turnover rates included the medial preoptic nucleus (MPN), suprachiasmatic nucleus (SCN), arcuate nucleus (AN), and ME. DA turnover rates also were measured in the MPN, ME, and AN. ME LHRH and serum hormone concentrations were measured by RIA. Between 0900-1 200 h, proestrous serum estradiol was elevated, but other serum hormones were basal, and CA turnover rates in the brain were low. However, ME LHRH concentrations increased significantly between 0900-1200 h on proestrus. Between 1200-1500 h, serum LH, FSH, PRL, and progesterone levels increased and ME LHRH levels declined significantly; during this time interval (1200-1400 h), a significant rise in ME NE and DA turnover rates occurred. Between 1500-1700 h on proestrus, while serum gonadotropins were still rising toward peak concentrations, increased ME NE turnover rates were maintained, but increased NE turnover rates also were evident in MPN, SCN, and AN. During this same time interval (1500-1700 h), a marked decline in ME and AN DA turnover rates occurred, although such rates remained unchanged within the MPN. There were no corresponding changes in MPN E turnover rates at any of the time intervals studied. The increased turnover rates of ME NE coupled with the concomitant decline in ME LHRH levels and the rise in plasma LH and FSH levels suggest that increased NE release may be important in initiating preovulatory LH and FSH surges. These changes in brain neurotransmitters and serum hormones are not the result of a diurnal rhythm, since corresponding changes in CA turnover rates or serum gonadotropins did not occur between (0900-1100 h and 1500-1700 h diestrous day 1.

UR - http://www.scopus.com/inward/record.url?scp=0019824770&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0019824770&partnerID=8YFLogxK

M3 - Article

VL - 108

SP - 1795

EP - 1802

JO - Endocrinology

JF - Endocrinology

SN - 0013-7227

IS - 5

ER -