Temporal and Other Effects of Catechol Estrogens on Prolactin Secretion in the Rat

Shin, Seon H.; Bates, L.; Jellinck, Peter H.

doi:10.1159/000123260

Cited by 6 publications

(8 citation statements)

References 26 publications

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“…The results confirm our earlier findings with 2-OHEi and 2-0HE2 [29] and extend them to other catechol estrog ens. In all cases tested, the effect on PRL secretion was more pronounced when the catechol estrogens were admin istered to rats bearing implants of E2 and could not be The estrogens in ethanol/saline were injected as a bolus through an indwelling atrial cannula into male rats (280 330 g) and blood samples (70 pi) collected for PRL determination by RIA.…”

Section: Resultssupporting

confidence: 91%

“…The tubes were sealed with C'ritoseal (Sherw'ood Medical Industries), centrifuged at 11,500 rpm for 10 min at 4 C and plasma samples harvested. It had been established previously [28,29] that, under these experi mental conditions, the basal level of PRL was not affected by con tinuous blood sampling, by reduction in blood volume, nor by the alcohol in the saline.…”

Section: Methodsmentioning

confidence: 58%

“…Previously we have shown [29] that 2-hydroxyestrone (2-OHEi), which is devoid of significant uterotrophic activ ity [12,18] and had had no effect in untreated male rats, produced a 5-to 6-fold elevation in plasma PRL level after its administration to rats implanted with E2. In this paper, we compare the effect of several other catechol estrogens as…”

mentioning

confidence: 99%

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Effect of Catechol Estrogens on Prolactin Secretion in the Rat: Lack of Correlation with Estrogenic Activity

Jellinck¹,

Shin

1987

Neuroendocrinology

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Temporal changes in plasma prolactin (PRL) levels caused by the administration of a number of different catechol estrogens to freely-moving conscious male rats were determined. The steroids with a wide range of affinity for the estrogen receptor were given in a single bolus (100 µg/kg) into the right atrium via an indwelling cannula. Plasma PRL concentration was monitored by taking blood samples every 2 min. The effect on PRL secretion was found to be more pronounced when the catechol estrogens were administered to rats bearing implants of estradiol and could not be correlated with their Kd values for the estrogen receptor. The synthetic estrogen, diethylstilbestrol, behaved anomalously by producing an elevation in plasma PRL only in estradiol-primed animals or after prolonged infusion. Diethylstilbestrol-treated rats showed no PRL response to 2-hydroxyestrone unlike those bearing Silastic capsules of estradiol. The experiments support the hypothesis that catechol estrogens generally act as short-term dopamine agonists, lowering PRL, but that those which possess estrogenic activity also show a more prolonged PRL-elevating effect. Thus, the overall action of this group of steroids will be determined by factors which influence these two parameters.

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Section: Resultssupporting

confidence: 91%

Section: Methodsmentioning

confidence: 58%

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Effect of Catechol Estrogens on Prolactin Secretion in the Rat: Lack of Correlation with Estrogenic Activity

Jellinck¹,

Shin

1987

Neuroendocrinology

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“…However, the possibility cannot be excluded that catechol estrogens, secreted from the reactive cells in the median eminence, enter the portal vessel and become involved in the regulation of pituitary function, since catechol estrogens sensitize cultured pituitary cells to LHRH (18). In addition, catechol estrogens modulate the secretion of prolactin from the pituitary gland (4,15,23,45,48).…”

Section: Discussionmentioning

confidence: 99%

Immunocytochemical localization of catechol estrogens in the rat pituitary gland. II. Median eminence.

Inoue

Yoshizawa

1989

Acta Histochem. Cytochem

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Light and electron microscopic immunocytochemical observations of catechol estrogens in the median eminence of the rat were made using a specific antibody raised against 2-hydroxyestrone coupled to bovine serum albumin and the peroxidase-antiperoxidase technique. Immunoreactive deposits were found in the tanycytes and glia cells. The terminal processes of the reactive cells ended in the perivascular space. Catechol estrogen can cause elevation and/or suppression of serum levels of luteinizing hormone (LH). Thus, our results suggest that catechol estrogens in the reactive cells may be involved in the regulation of secretion of luteinizing hormone releasing hormone (LHRH) in the median eminence.Catechol estrogens are the end products of the biotransformation of estrogen in man and rat. Parvizi and Ellendorff (40) initially demonstrated the action of catechol estrogens by showing that the secretion of luteinizing hormone (LH) by the anterior pituitary is inhibited by microinjection of 2-hydroxyestradiol (2-OHE2) in the amygdala of the miniature pig. They mentioned that it remained to be established whether 2-OHE2 can cross the blood-brain barrier or whether it is synthesized in the brain, or both. Subsequently, several authors reported that estrogens are hydroxylated to become Catechol estrogens in the brain as well as in the liver (2, 12, 13, 42). The arcuatemedian eminence region, in particular, contained the highest levels of activity of estrogen 2,4-hydroxylase in rat brain (56). Furthermore, the metabolic clearance rate of catechol estrogens in the bloodstream is very high (28). Consequently, catechol estrogens in the bloodstream are assumed not to produce any local effects in the brain. Despite much speculation, the mechanism of the action of catechol estrogens in the brain remains unknown. The specific localization of catechol estrogens might give further clues to their function. We have already reported that the localization of catechol estrogens can be determined by immunocytochemical methods (19, 20). In the present study we examined the distribution of catechol estrogens in the median eminence of the rat. The tanycytes and the glia cells in median eminence were all found to contain catechol estrogens.

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“…However, it does not rule out catechol estrogen-catechol amine interaction in other neuroendocrine functions, parti cularly in the suppression of prolactin secretion [13,34].…”

Section: Discussionmentioning

confidence: 99%

Differential Effects of Catechol Estrogens, Progestins and CI-628 Administered by Constant Infusion on the Central and Peripheral Action of Estradiol

Jellinck¹,

Luine²,

McEwen³

1982

Neuroendocrinology

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By means of continuous infusion by Alzet minipumps, we tested the ability of the catechol estrogens, 2-hydroxyestrone (2-OHE₁) and 2-hydroxyestradiol (2-OHE₂), as well as two progestins and the anti-estrogen, CI-628, to block the action of estradiol (E2) on sexual behavior, LH surge frequency, uterine weight increase and glucose-6-phosphate dehydrogenase (G6PDH) activity in the uterus and pituitary of ovariectomized rats. Neither catechol estrogen produced inhibitory effects, whereas the potent progestin, R-5020 (5 μg/h), and CI-628 (50 μg/h) inhibited the E2-induced increase in the LH surge frequency and lordosis response. Progesterone at 20 μg/h and CI-628 at 5 μg/h did not influence these end points. In the pituitary and uterus, the concurrent administration of R-5020 and E2 attenuated the increase of G6PDH activity. As expected, CI-628 inhibited the action of E2 on G6PDH but was more effective in doing so at the lower of the two doses. CI-628 (50 μg/h) also blocked the neuroendocrine and behavioral effects of 2-OHE₂ (1 μg/h) and 4-hydroxyestradiol (0.1 μg/h). Taken together with our previous studies, these results are consistent with the notion that the catechol estrogens exert effects on sexual behavior and LH surge frequency by virtue of their estrogenic properties rather than by other means.

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Temporal and Other Effects of Catechol Estrogens on Prolactin Secretion in the Rat

Cited by 6 publications

References 26 publications

Effect of Catechol Estrogens on Prolactin Secretion in the Rat: Lack of Correlation with Estrogenic Activity

Effect of Catechol Estrogens on Prolactin Secretion in the Rat: Lack of Correlation with Estrogenic Activity

Immunocytochemical localization of catechol estrogens in the rat pituitary gland. II. Median eminence.

Differential Effects of Catechol Estrogens, Progestins and CI-628 Administered by Constant Infusion on the Central and Peripheral Action of Estradiol

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