Effects of Intraventricular Infusions of Norepinephrine and Dopamine on LH Release and Ovulation in the Rabbit

Sawyer, Charles H.; Hilliard, Jessamine; Kanematsu, Shigeto; Scaramuzzi, Rex; Blake, Charles A.

doi:10.1159/000122323

Cited by 91 publications

(33 citation statements)

References 19 publications

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“…Consequently, the results lend further credence to the postulated role of NE in stimulating the preovulatory release of LH and that induced by ovarian steroids [Sawyer et al, 1947;McCann and Moss, 1975]. The present results and those of previous studies [Rubinstein and Sawyer, 1970;Sawyer et al, 1974] also raise the possibility that E might play a physiological role as a stimulator of LH release. Recently, terminals of epinephrinergic neurons have been shown to be present in the hypothalamus [H ó k felt et al, 1974] and they may play a physiological role.…”

Section: Discussionsupporting

confidence: 88%

Re-Evaluation of the Role of Catecholamines in Control of Gonadotropin and Prolactin Release

Vijayan¹,

McCann²

1978

Neuroendocrinology

169

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The effect of microinjection of catecholamines into the 3rd brain ventricle on plasma gonadotropins and prolactin (Prl) titers was evaluated in estrogen and progesterone-primed, ovariectomized (OEP) rats which are a particularly sensitive test animal for LH-RH and the responses compared to those obtained in ovariectomized (OVX), unprimed animals. Intraventricular injection of isotonic saline had no effect on plasma gonadotropins or Prl. The injection of dopamine (DA) into the 3rd ventricle elevated plasma LH in the OEP rats at doses of 4 or 20 µg, but the elevation obtained with the 10 µg dose was not significant. A greater effect was obtained with 20 µg doses of both norepinephrine (NE) and epinephrine (E), with E being the most effective of the 3 catecholamines. Apomorphine (APO) also elevated plasma LH following its injection into the 3rd ventricle in the OEP rats. Since these animals were etherized for removal of blood samples and microinjections into the ventricle, a group of animals was used with in-dwelling cannulae in the external jugular vein. In these animals, DA also elevated plasma LH. In OVX animals, the intraventricular injection of DA was without effect on plasma LH, but small transient increases in plasma LH were obtained with 20 µg doses of NE or E. The action of DA in the OEP rat was not prevented by the prior injection of diethyldithiocar-bamate (DDC) which inhibits NE synthesis. Dopamine, apomorphine, and another DA receptor-stimulating drug, Piribedil (ET-495), lowered plasma Prl following their intraventricular injection in all conditions. There were no effects of any of the drug treatments on plasma FSH. It is concluded that intraventricular DA can stimulate LH release in the steroid-primed rat but that NE and E appear to be more effective in this regard. Epinephrine was the most effective catecholamine in stimulating LH release. Dopamine clearly

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Section: Discussionsupporting

confidence: 88%

Re-Evaluation of the Role of Catecholamines in Control of Gonadotropin and Prolactin Release

Vijayan¹,

McCann²

1978

Neuroendocrinology

169

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“…However, the effects of intraventricular monoamine injections should be interpreted with caution as there is evidence that such effects are non-specific (Hokfeldt & Fuxe, 1972). In oestrogen-primed rabbits the intraventricular injection of noradrenaline stimulated LH release, but dopamine not only failed to release LH but even blocked the ability of noradrenaline to induce such a rise (Sawyer et al, 1974). Similarly more recently, using ovariectomized steroid-primed rats, it has been found that the intraventricular administration of dopamine had no stimulatory effect on LH release in contrast to noradrenaline (Kreig & Sawyer, 1976).…”

Section: The Gonadotrophins (Lh and Fsh)mentioning

confidence: 95%

The Role of Serotonin and Dopamine in Hypothalamic‐pituitary Function

Smythe¹

1977

Clinical Endocrinology

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“…Hypothalamic norepinephrine (NE) plays an important role in the control of reproduction because its effects on sexual behavior and on the secretion of gonadotropin, especially luteinizing hormone (LH), are firmly established (Sawyer et al 1974, Kalra & Kalra 1983, Etgen et al 1992. In contrast, biochemical and molecular events in noradrenergic neurons in the brainstem where hypothalamic NE is derived have received little attention.…”

Section: Introductionmentioning

confidence: 99%

Tyrosine hydroxylase and norepinephrine transporter mRNA levels increase in locus coeruleus after coitus in rabbits

Yang

Pau²,

Hg³

1997

Journal of Molecular Endocrinology

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Hypothalamic norepinephrine (NE) plays an important role in the control of sexual behavior and in the secretion of gonadotropin. Our previous study showed that coitus induced simultaneous increases in hypothalamic NE and GnRH releases in female but not in male rabbits. To investigate the activities in noradrenergic neurons during the coitus-induced process of an LH surge, we measured tyrosine hydroxylase (TH, the rate-limiting enzyme in NE synthesis) and NE transporter (NET, a key protein for NE cellular reuptake) mRNA levels in locus coeruleus (LC) noradrenergic cells in female New Zealand White rabbits. Changes in LC-TH and LC-NET mRNA levels were also measured in males as controls. Female rabbits were killed before coitus and at 15, 30, 60, 120, and 240 min after coitus (n=6-7/time point); males were killed before and at 30, 60, and 120 min after coitus (n=3/time). Individual brainstems were sectioned, the LC neurons punched, and TH and NET mRNAs were quantified by ribonuclease protection assay (RPA). Rabbit-specific TH (330 bp) and NET (503 bp) cDNAs were used as probes in the RPA for gene-specific signals. A rabbit 'house-keeping' cDNA (cyclophilin, 158 bp) was also cloned and used as an internal marker for tissue RNA content. Trunk blood was collected to determine serum LH levels. In female rabbits, serum LH levels rose by 15 min after coitus, reached peak concentrations at 1-2 h, and declined thereafter. The time interval for changes in TH and NET mRNA levels in females was similar to that in serum LH levels. Both TH and NET mRNAs increased significantly by 15 min (73% and 85% respectively) and were elevated for 2 h (87% and 111% respectively). TH mRNA levels returned to basal levels by 4 h after coitus, whereas NET mRNA values were elevated throughout the 4 h of observation. In contrast, LH, TH and NET mRNA levels did not change after coitus in males. The enhanced gene expression of both TH and NET in the LC in females, in accord with our previous demonstration of increased hypothalamic NE release, suggests that regulation of NE synthesis and reuptake is an integral part of the coitus-induced NE/GnRH/LH surge process that includes the initiation, sustenance or recovery of the release and/or storage of these neurochemicals.

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Effects of Intraventricular Infusions of Norepinephrine and Dopamine on LH Release and Ovulation in the Rabbit

Cited by 91 publications

References 19 publications

Re-Evaluation of the Role of Catecholamines in Control of Gonadotropin and Prolactin Release

Re-Evaluation of the Role of Catecholamines in Control of Gonadotropin and Prolactin Release

The Role of Serotonin and Dopamine in Hypothalamic‐pituitary Function

Tyrosine hydroxylase and norepinephrine transporter mRNA levels increase in locus coeruleus after coitus in rabbits

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