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

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

doi:10.1016/0006-8993(87)90738-4

Cited by 27 publications

(12 citation statements)

References 44 publications

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“…This work was presented in abstract form at the 2nd International Congress of Neuroendocrinology, Bordeaux, France, June [24][25][26][27][28][29] 1990. The author would like to thank Bernadette Delaleu for expert assistance and Kirsten Rerat who prepared the English translation of the manuscript.…”

Section: Acknowledge Men Tsmentioning

confidence: 99%

Monoamine Content of the Stalk‐Median Eminence and Hypothalamus in Adult Female Sheep as Affected by Daylength

Thiéry

1991

J Neuroendocrinology

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In the ewe, plasma luteinizing hormone and prolactin concentrations exhibit seasonal variations. During long days, inhibition of pulsatile luteinizing hormone secretion is mediated by monoamines. In a model of ovariectomized ewes bearing a subcutaneous oestradiol implant, we previously showed that the steroid-dependent inhibition of luteinizing hormone involves the A15 dopaminergic nucleus of the retrochiasmatic area. In the present work, we compared the aminergic activities of tele-diencephalic structures in groups of ovariectomized ewes under artificial illumination for short versus long days (8 versus 16 h/day of light, respectively). Half the animals in each group were bearing a subcutaneous oestradiol implant. Using high-performance liquid chromatography and electrochemical detection, we measured the levels of amines and amine metabolites in 'punches' of tissues from regions containing luteinizing hormone-releasing hormone axon terminals or cell bodies and catecholaminergic structures. Concurrently, we checked the pulsatile luteinizing hormone release and plasma prolactin concentration to assess the ability of our model to mimic seasonal changes in the hormonal status.As expected, ovariectomized ewes with a subcutaneous oestradiol implant showed an inhibition of the pulsatile luteinizing hormone release under long days. A higher concentration of plasma prolactin was also observed under long days, without any effect of the steroid treatment. Under this light regimen, statistically significant higher contents of dopamine than under short days were found in the stalk-median eminence. Larger contents of homovanillic acid, a dopamine metabolite, and 4-hydroxy-3-methoxyphenylethyleneglycol (MHPG), a noradrenaline metabolite were observed in the infundibular nucleus, while the catecholamines themselves remained unchanged. Furthermore, oestradiol also significantly increased the content of MHPG in the latter structure. During long days, animals without oestradiol treatment exhibited a significant lower content of noradrenaline in the A15 nucleus, without any alteration of the dopamine content. Daylength or oestradiol treatment had no significant effects on the levels of amines or amine metabolites in the preoptic or septa1 areas. Thus, our results in the ewe underline the role played by the medial basal hypothalamus in the catecholaminergic regulation of seasonal changes in hormone release and suggest modifications in the turnover of the neurotransmitters in some structures.In the ewe, which is a short day breeder, annual variations in the secretion of luteinizing hormone (LH) and prolactin (PRL) accompany seasonal changes in reproductive activity (1 -3). The seasonal effect on LH (4, 5 ) and PRL secretion (6) has also been demonstrated in the ovariectomized ewe. During the period corresponding to anoestrus in the intact animals, the frequency of LH pulses in the ovariectomized females was slightly lower than during the breeding season, (steroid-independent inhibition), but the effect was fully expressed wh...

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Section: Acknowledge Men Tsmentioning

confidence: 99%

Monoamine Content of the Stalk‐Median Eminence and Hypothalamus in Adult Female Sheep as Affected by Daylength

Thiéry

1991

J Neuroendocrinology

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“…Noradrenaline is known to be one of the excitatory neurotransmitters for LH release (Tima & Flerko 1974, Kalra 1985, Osterburg et al 1987. Locus coeruleus (LC) is the major noradrenergic nucleus and sends projections to the entire CNS, including areas involved in GnRH synthesis and secretion (Swanson & Hartman 1975, Foote et al 1983, Wright & Jennes 1993.…”

Section: Introductionmentioning

confidence: 99%

Changes in α-estradiol receptor and progesterone receptor expression in the locus coeruleus and preoptic area throughout the rat estrous cycle

Helena¹,

Poletini²,

Sanvitto³

et al. 2006

Journal of Endocrinology

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We have previously shown that the locus coeruleus (LC) is essential for triggering surges of LH. Since LC neurons are responsive to estradiol, which induces progesterone receptor (PR) expression, this study aimed to investigate whether LC neurons express the -estradiol receptor ( ER) and PR as well as comparing such responses to that observed in the preoptic area (POA). Female rats were perfused at 10, 14 and 16 h on each day of the estrous cycle, and a blood sample was collected for estradiol, progesterone and LH measurements. ER-and PR immunoreactive (ir) neurons were detected in POA and LC by immunocytochemistry (ICC). Higher plasma estradiol levels were observed on the day of proestrus, when a smaller number of ER-ir POA neurons were detected. An increase in the number of ER-ir neurons were observed at 16 h of proestrus and estrus. The number of PR-ir neurons increased in POA only at 16 h of proestrus, and remained unchanged during all other days and times. The profile of ER-ir and PR-ir neurons in LC changed over the estrous cycle, with a lower expression on metestrus morning and reaching a peak on diestrus afternoon before declining on the day of proestrus. However, on estrus afternoon, ER-ir neurons increased, while PR-ir neurons decreased which may be related to the prolactin surge of estrus. These data show that LC neurons express ER and PR and seem to be more sensitive to variations in estradiol than POA. Also, the fluctuation in ER and PR observed for LC neurons seems to accompany the hormonal events that occur during the estrous cycle. This profile of ER and PR expression might be related to the ability of estradiol and progesterone in regulating the activity of LC neurons, which could be associated to the control mechanisms of LH and prolactin release.

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“…Dopamine and norepinephrine were measured in homogenates prepared from medial basal hypothalamus and anterior pituitary as described previously [27,34]. Briefly, frozen tissue was homogenized in 0.1 N HCI containing 1 m M EDTA and 0.57 m M ascorbic acid.…”

Section: Ateria Ls and M Eth O D Smentioning

confidence: 99%

N-Methyl-Aspartic Acid Lesions of the Arcuate Nucleus in Adult C57BL/6J Mice: A New Model for Age-Related Lengthening of the Estrous Cycle

May

Kohama²,

Finch

1989

Neuroendocrinology

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We report a new effect of the excitotoxin N-methyl-aspartic acid (NMA) on adult mice. Besides confirming cell loss in the arcuate nucleus of animals treated as adults, we also observed lengthened estrous cycles. Cycling female C57BL/6J mice were treated with subcutaneous injections of NMA and estrous cycles monitored for 30 days. NMA treatment lengthened average estrous cycle length by 1 day, to 5.6 days. The elongated cycles were due to an increase in the frequency of 5- and 6-day cycles at the expense of 4-day cycles. This effect was observed in mice aged 4 and 7 months; however, 10-month-old mice had irregular cycles and a higher mortality rate following NMA, which precluded cycle analysis. NMA caused a region-specific 30–45% cell loss in the rostral portions of the arcuate nucleus; no cell loss was detected in the adjacent ventromedial nucleus. Possible neuronal substates for NMA lesions, as analyzed by in vitro receptor autoradiography for glutamate receptor subtypes, include a high density of kainate receptors in the arcuate nucleus; there was little specific binding of ligands to NMDA and quisqualate receptors. Consistent with the regional pattern of cell loss, little specific binding of any glutamatergic ligand was observed in the VMN. NMA caused weight gain in all age groups. Serum LHand PRL were unaffected by NMA. The transition from 4-day to 5- and 6-day estrous cycles produced by NMA treatment mimics the early age-related changes in estrous cycle patterns in rodents. This new model will be useful in analyzing the contributions of neuroendocrine changes in the arcuate nucleus to reproductive senescence.

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

Cited by 27 publications

References 44 publications

Monoamine Content of the Stalk‐Median Eminence and Hypothalamus in Adult Female Sheep as Affected by Daylength

Monoamine Content of the Stalk‐Median Eminence and Hypothalamus in Adult Female Sheep as Affected by Daylength

Changes in α-estradiol receptor and progesterone receptor expression in the locus coeruleus and preoptic area throughout the rat estrous cycle

N-Methyl-Aspartic Acid Lesions of the Arcuate Nucleus in Adult C57BL/6J Mice: A New Model for Age-Related Lengthening of the Estrous Cycle

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