Cancer. Apr 1;53(7) Comparative effects of tamoxifen and bromocriptine on prolactin and pituitary weight in estradiol-treated male rats. Lyle SF. Hello Lyle: Can you or anyone suggest a reliable overseas source of bromocriptine? Thanks – I’ve used antiaging-systems in the past – very. Bromocriptine for fat loss Logging your progress. Been educating myself lately by reading good authors like Lyle. On a journey to come down.
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Effects of bromocriptine on serum prolactin levels, pituitary weight and immunoreactive prolactin cells in estradiol-treated ovariectomized rats: Ribeiro 1P. Spritzer 1,2L.
Barbosa-Coutinho 3M. Oliveira 3M. Pavanato 1I. Silva 1 and F. The present study was designed to assess the effects of bromocriptine, a dopamine agonist, on pituitary wet weight, number of immunoreactive prolactin cells and serum prolactin concentrations in estradiol-treated rats. Data were compared with those obtained for intact control rats. Administration of both doses of estrogen increased serum prolactin levels. Bromocriptine decreased prolactin levels in all estrogen-treated rats.
The general antiprolactinemic and antiproliferative pituitary effects of bromocriptine treatment reported here validate the experimental model of estrogen-induced hyperprolactinemic rats. Estrogen is known to have a stimulatory role in prolactin synthesis and release 1,2.
This steroid also induces pituitary tumors, depending on the experimental model and dose 3,4.
Bromocriptine by Lyle McDonald
Dopamine, acting via its specific receptor in the anterior pituitary, tonically inhibits pituitary prolactin secretion and lactotroph proliferation On the other hand, estradiol appears to be a potent antidopaminergic agent in vivo 8. Bromocriptine 2-bromo- a -ergocryptine, a dopamine agonist has been used to examine the neuroendocrine mechanism of dopamine that controls prolactin secretion in vivo.
In addition, dopamine agonist therapy for pituitary prolactinomas results in the reduction of prolactin secretion and tumor regression 9, There are only a few animal models available which are sensitive to dopamine agonists, such as the SMtTW tumor, a spontaneous prolactin-secreting transplantable tumor 4and some studies using estrogen-induced hyperprolactinemia bromocriptnie pituitary enlargement 3, These studies did not report which doses and duration of in vivo estrogen administration are required to promote prolactin hypersecretion without pituitary enlargement or if bromocriptine effects on prolactin levels and lactotroph proliferation may vary with different schedules of estrogen treatment.
The present study was designed to assess the effects of bromocriptine bromocriltine pituitary wet weight, number of prolactin cells and serum prolactin levels in ovariectomized animals subacutely or chronically stimulated with estrogen, in order to validate an experimental model for the study of the interaction between estrogen and dopamine in controlling prolactin secretion and lactotroph proliferation in vivo. Bromocrpitine were compared with those obtained for intact or ovariectomized control groups.
Ninety-four female Wistar rats, 3 months old, were maintained under conditions of controlled light and temperature with free access to water and standard rat chow. Rats were bilaterally ovariectomized under light ether anesthesia except for nine intact female rats which were used as a control group. Bromocriptine Sandoz was injected daily 0.
Twenty-four hours after the last hormone or vehicle injection, rats were decapitated, trunk blood samples were collected, and serum was harvested and stored at o C until assayed for prolactin by a double-antibody radioimmunoassay. Pituitary glands were removed immediately after decapitation and wet weights were determined with an electronic balance.
Pituitary glands were placed in formalin and processed for prolactin immunohistochemistry as previously described 13, Rat anti-prolactin antibody produced in rabbits was used at 1: The primary antiserum was applied for overnight incubation, treated with biotin anti-rabbit IgG for 30 min and finally incubated with the avidin-biotin peroxidase complex Vector, Burlingame, CA for 60 min.
Controls consisted of 2 sections of normal rat pituitary. One section was processed exactly as done for the experimental sections positive control and the other, in which the primary antibody was omitted, was used as the negative control.
Rinsing with phosphate buffered saline was performed after each step. Two hundred nucleated cells were counted at X, using a 1-mm 2 grid in the microscope eyepiece, and the number of prolactin-containing cells was recorded. Cells were independently counted by 3 observers.
The data were tabulated, the average count for each anterior pituitary was calculated and the result was reported as percent of cells containing prolactin in relation to total cellularity. Serum prolactin content was measured by a double-antibody radioimmunoassay using materials kindly provided by the NIADDK. Prolactin was radioiodinated by the chloramine T method. Statistical analysis was performed by either the Student t -test or by analysis of variance, followed by Duncan’s multiple range test for the comparisons of multiple means.
Bromovriptine 2 illustrates the serum prolactin levels of intact rats and rats treated with estradiol alone or in combination with bromocriptine. The addition of bromocriptine to the treatment with estradiol valerate resulted in a significant decrease in serum prolactin levels when compared to the respective control group treated with estrogen alone.
When these groups were compared to intact control rats, only ovariectomized rats without hormonal treatment presented a significantly lower number of prolactin cells.
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As shown in Figure 1 B, subsequent administration of bromocriptine to the rats treated with the highest dose of estrogen resulted in a significant reduction in the percentage of immunoreactive prolactin cells. Figure 1 – Effects of estradiol valerate alone or in combination with bromocriptine on the percent of immunoreactive prolactin cells in ovariectomized rats.
The number of animals is given in parentheses. This state of “functional hyperprolactinemia”, which is similar to human idiopathic hyperprolactinemia 17is a suitable model for the study of the neuroendocrine bromocriptnie of prolactin secretion, with hromocriptine serum prolactin levels being taken as an example in the present study.
Thus, our findings obtained under different experimental conditions of estrogen administration to ovariectomized rats indicate two states of estrogen-dependent hyperprolactinemia: The present data show that bromocriptine decreased serum prolactin levels under all experimental conditions, even when no pituitary enlargement was observed.
Using increasing doses of bromocriptine in estrogen-treated rats, we have recently reported that the effect of bromocriptine in reducing the number of immunoreactive lactotrophs was observed only after long-term estrogen treatment including bromocriptine administration for 12 days lyl No difference was observed when bromocriptine was administered for the last 5 days of short-term estrogen treatment, suggesting that the duration of bromocriptine treatment required to detect a change in the number of lactotrophs by immunohistochemistry should be longer than 5 days In the present study, we demonstrated a decline in lactotroph bromocriptie after only two weeks of estrogen treatment when bromocriptine was lyke for 12 days.
Our experiments do not address the question of the mechanisms underlying the different responses of prolactin cell proliferation to bromocriptine.
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However, it will be interesting to determine whether other schedules of concomitant administration of estrogen and bromocriptine as well as the association with other steroidal hormones have the same effects. In conclusion, the present report describes a useful experimental model in which hypotheses concerning the mechanisms of action of estradiol in the induction of prolactin hypersecretion, pituitary enlargement and lactotroph proliferation can be tested. The general antiprolactinemic and antiproliferative pituitary effects of bromocriptine treatment reported here validate this model of estrogen-induced hyperprolactinemic rats.
Further studies are needed to define the exact role of dopamine and dopamine agonists at the molecular level in hyperprolactinemic states and their connection with steroidal hormones. Serum and pituitary prolactin levels before, during and after puberty in female rats.
Bromocrpitine Journal of Physiology Effects of estrogen and progesterone on serum and pituitary prolactin levels in ovariectomized rats. Effects of oestrogen and bromocriptine on in vivo secretion and mitosis in prolactin cells. Effect of the slow-release formulation of somatuline BIM on estrogen-induced hyperprolactinemia and lactotroph hyperplasia in the female rat. Dopamine receptors on intact anterior pituitary cells in culture: Inhibitory effects of the dopamine agonists quinagolide CV and bromocriptine on prolactin secretion and growth of SMtTW pituitary tumours in the rat.
Normal structural dopamine type 2 receptor gene in prolactin-secreting and other pituitary tumors.
Journal of Clinical Endocrinology and Metabolism Antidopaminergic activity of estrogens on brmocriptine release bromodriptine the pituitary level in vivo. Molecular and Cellular Endocrinology Size reduction of macroprolactinomas by bromocriptine or lisuride treatment. Human prolactin-producing adenomas and bromocriptine: A histologic, immunocytochemical, ultrastructural, and morphometric study. Comparative effects of tamoxifen and bromocriptine on prolactin and pituitary weight in estradiol-treated male rats.
Defective central nervous system dopaminergic function in rats with estrogen-induced pituitary tumours, as assessed by plasma prolactin concentrations.
Progestin effects on prolactin secretion and on immunoreactive prolactin cells in estradiol-treated ovariectomized rats. Hormone and Metabolic Research Effects of bromocriptine on prolactin cellular hypertrophy, proliferation and secretory activity in diethylstilbestrol-induced pituitary tumors. Morphologic effects of bromocriptine on spontaneously occurring pituitary prolactin-cell hyperplasia in old Long-Evans rats.
American Journal of Pathology Effects of tamoxifen on prolactin levels, pituitary immunoreactive prolactin cells and uterine growth in estradiol-treated bromociptine rats.
Evidence for a pathological reduction in brain dopamine metabolism in idiopathic hyperprolactinemia. Acta Endocrinologica Received April 19, Accepted November 4, All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License. Services on Demand Journal. Braz J Med Biol Res, JanuaryVolume 30 1 Short Communication Effects of bromocriptine on serum prolactin levels, pituitary weight and immunoreactive prolactin cells in estradiol-treated ovariectomized rats: Correspondence and Footnotes Address for correspondence: How brromocriptine cite this article.