LH Discharge Induced by Medial Preoptic Implantation of Estrone or Dopamine in the Ovariectomized Estradiol Primed Rat

Kawakami, Michiyuki; Kimura, Fukuko; Manaka, M; Kawagoe, Shinnosuke

doi:10.1507/endocrj1954.22.549

Cited by 15 publications

(10 citation statements)

References 12 publications

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“…Further that lesioning of the ZI, or injection of the non-specific DA antagonist haloperidol [41) at 2 pg/side/ rat inhibited ovulation, and injections of DA into the ZI at 2 pg into ovariectomised OB-primed rats induced a signifi cant rise in plasma LH [33]. This is in agreement with other authors who have evidence for a stimulatory role for DA on GT release and ovulation [22,28,44,45,56,57], The present report investigates the receptor subtype involved in the me diation of the I-H tract activity. Selective Di and D2 dopa minergic agents were tested for their potential stimulatory or inhibitory effects on GT release and ovulation when ad ministered acutely into the ZI in anaesthetised rats.…”

Section: Discussionsupporting

confidence: 91%

Dopaminergic Neurones in the Zona incerta Exert a Stimulatory Control on Gonadotrophin Release via D<sub>1</sub> Dopamine Receptors

James¹,

Mackenzie²,

Tuohy-Jones³

et al. 1987

Neuroendocrinology

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The zona incerta (ZI) is a site of dopamine nerve terminals and part of the incertohypothalamic tract (I-H). Previous findings indicate that dopamine in the ZI has a stimulatory control on the release of luteinizing hormone (LH) and occurrence of ovulation. The effect of acute administration into anaesthetised rats of selective D₁ and D₂ dopamine agonists and antagonists injected into the ZI on plasma luteinizing hormone (LH) and on the occurrence of ovulation has now been investigated. It was found that bilateral injections on the day of pro-oestrus of a selective D₁ antagonist, Sch 23390, inhibited ovulation at 10 µg/side/rat. Unilateral injections of a selective D₁ agonist, SKF 38393, at 10 µg/rat stimulated a significant rise in plasma LH concentration in ovariectomised oestrogen-primed rats, and this was partially reversed by systemic pre-treatment with Sch 23390. The selective D₂ agonist, LY 171555, and D₂ antagonists, sulpiride and domperidone, had no effect on plasma LH levels or ovulation. This indicates that D₁ receptors (but not D₂ receptors) in the ZI are involved in the control of gonadotrophin release and may have a physiological function in reproductive processes.

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Section: Discussionsupporting

confidence: 91%

Dopaminergic Neurones in the Zona incerta Exert a Stimulatory Control on Gonadotrophin Release via D<sub>1</sub> Dopamine Receptors

James¹,

Mackenzie²,

Tuohy-Jones³

et al. 1987

Neuroendocrinology

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“…Previous studies in our laboratory have shown that the media! preop tic administration of dopamine also facilitated the circa dian rise in LH secretion in ovariectomized estrogenprimed rats [9,10]. Whether there is a certain functional in teraction between NT and dopamine in the preoptic area, similar to that observed between cholecystokinin and dopa mine [6], in controlling LH secretion will be studied soon.…”

Section: Discussionmentioning

confidence: 92%

Effects of Preoptic Microinjection of Neurotensin on Luteinizing Hormone Secretion in Unanesthetized Ovariectomized Rats with or without Estrogen Priming

Akema¹,

Praputpittaya²,

Kimura³

1987

Neuroendocrinology

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Effects of microinjection of neurotensin (NT) into the medial preoptic area on luteinizing hormone (LH) release were examined in unanesthetized ovariectomized rats with or without estrogen priming. Microinjection of NT (100 ng) into the medial preoptic area of ovariectomized estrogen-primed rats significantly facilitated the circadian afternoon rise of LH secretion as compared to the hormone values in control animals microinjected with physiological saline. The timing of the afternoon LH rise was not altered by the peptide. In ovariectomized estrogen-unprimed rats, on the other hand, NT did not affect the existing pulsatile LH secretion nor induced an afternoon rise of the hormone secretion. These results show that NT can stimulate the preoptic LH release mechanism which undergoes the circadian clock under the influence of estrogen.

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“…NA, DA and 5HT all have dual effects on gonadotrophin release. Their stimulatory effects are thought to be mediated in the MPOA in particular (31)(32)(33)(34). NA may also be stimulatory in the ME and ARN (32) and 5HT in the ME (35).…”

Section: Discussionmentioning

confidence: 99%

Effects of DPDPE (a specific delta-opioid receptor agonist) and naloxone on hypothalamic monoamine concentrations during the pre-ovulatory LH surge in the rat

Yılmaz

Gilmore

Wilson

1998

European Journal of Endocrinology

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We have investigated the inter-relationship between the opioid and aminergic systems in the control of secretion of the pro-oestrous LH surge and the involvement of d-opioid receptor subtypes in this process. Conscious female rats bearing a cannula in the femoral artery were injected i.p. with a selective d-opioid receptor agonist (DPDPE) either alone or with the opioid antagonist (naloxone) at 1300 h on the day of pro-oestrus. Blood samples were collected hourly between 1500 h and 1900 h, and plasma LH levels were measured by RIA. At the end of this period (1900 h), the animals were autopsied and the concentrations of the amines (noradrenaline (NA), dopamine (DA), 5-hydroxytryptamine (5HT)) and their metabolites (dihydroxyphenolglycol (DHPG) and 5-hydroxyindoleacetic acid (5HIAA), metabolites of NA and 5HT respectively) were determined by HPLC with electrochemical detection in the medial preoptic area, suprachiasmatic nucleus, median eminence and arcuate nucleus.DPDPE abolished the LH surge and concomitantly decreased hypothalamic NA and DHPG concentrations in all the areas examined. The levels of DA, 5HT and 5HIAA were also reduced in all hypothalamic regions studied, except DA and 5HIAA in the suprachiasmatic nucleus. Naloxone reversed these inhibitory effects of the d-agonist.We conclude that activation of d-opioid receptors may exert an inhibitory effect on LH release. The effect is probably an indirect one mediated by the monoaminergic systems, as they are suppressed by DPDPE in nearly all the hypothalamic regions studied.

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LH Discharge Induced by Medial Preoptic Implantation of Estrone or Dopamine in the Ovariectomized Estradiol Primed Rat

Cited by 15 publications

References 12 publications

Dopaminergic Neurones in the Zona incerta Exert a Stimulatory Control on Gonadotrophin Release via D<sub>1</sub> Dopamine Receptors

Dopaminergic Neurones in the Zona incerta Exert a Stimulatory Control on Gonadotrophin Release via D<sub>1</sub> Dopamine Receptors

Effects of Preoptic Microinjection of Neurotensin on Luteinizing Hormone Secretion in Unanesthetized Ovariectomized Rats with or without Estrogen Priming

Effects of DPDPE (a specific delta-opioid receptor agonist) and naloxone on hypothalamic monoamine concentrations during the pre-ovulatory LH surge in the rat

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