Regulation of GH and TSH release from hyperplastic and ectopic pituitaries: Effects of dopamine in vitro

Esquifino, Ana I.; Agrasal, C.; Steger, Richard W.; Fernández‐Ruiz, Javier; Amador, A. G.; Bartke, Andrzej

doi:10.1016/0024-3205(89)90251-8

Cited by 8 publications

(5 citation statements)

References 26 publications

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“…The increase in plasma PRL levels with age in sham-operated rats is in agreement with previous studies (14,17), indicating that the animals used in this study are in the pubertal phase. For this reason comparisons were made between in vitro pituitary secretions from animals of the same stage of sexual maturation.…”

Section: Discussionsupporting

confidence: 92%

“…In vitro basal GH secretion from in situ pituitaries was not changed by pituitary grafting nor by CyA treatment. Also, GH was secreted from the ectopic pituitaries, as shown in previous reports obtained in in vivo (32) and in vitro studies (1 1). Addition of DA to the incubation media reduced GH release from the in situ and ectopic pituitaries through specific receptors found on the somatotrophs (11,33,34).…”

Section: Discussionsupporting

confidence: 73%

“…After 60 min, the medium was removed and discarded, and 1 ml of fresh medium was added. An hour later the medium was removed and saved for the measurement of the basal PRL, GH, and LH release and replacing with medium containing DA (lo-' M) (13,14) or TRH ( M ) (15). One h later, the incubation was finished and the medium was removed and kept frozen until assayed to measure PRL, GH, and LH release.…”

Section: Drug Treatment and Samplingmentioning

confidence: 99%

“…PRL, GH, and LH were measured by specific radioimmunoassays using reagents provided by the NIDDK as described previously (13,14,16). The results were expressed in terms of NIDDK rat PRL, GH, and LH standards RP-3.…”

Section: Drug Treatment and Samplingmentioning

confidence: 99%

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Cyclosporine Effects on in vitro Responsiveness of Anterior Pituitary Hormone Release to Dopamine and Thyrotropin‐Releasing Hormone in Young Female Rats

Arce

et al. 1995

J Neuroendocrinology

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Endocrine side effects of the immunosuppressive drug cyclosporine (CyA) include changes in anterior pituitary hormone secretion. The aim of the present study was to examine the effects of CyA on the responsiveness of in situ and ectopic anterior pituitary prolactin (PRL), growth hormone (GH) and luteinizing hormone (LH) release response to dopamine (DA) and thyrotropin-releasing hormone (TRH) treatment in young female rats, and to evaluate the possible PRL participation in these effects. Thirty day old rats were rendered hyperprolactinemic by transplanting an anterior pituitary gland of a littermate donor, under the kidney capsule, and were then injected with CyA or vehicle for 2 or 8 days. Sham-operated rats were used as controls and treated in the same way. CyA treatment prevented the increase in plasma PRL levels which occurred in controls after pituitary grafting. In vitro basal PRL release of in situ pituitaries from either sham-operated and/or pituitary-grafted animals was decreased by CyA treatment at any point studied. Basal in vitro secretion of GH was only decreased in the in situ pituitaries from grafted animals after 2 days of CyA therapy. The presence of an ectopic pituitary lead to an increase in the in vitro basal LH secretion from in situ pituitaries as compared to those from sham-operated rats. Basal LH release rates were not changed by CyA treatment, although the LH release in vitro did increase in the in situ pituitaries from sham-operated animals treated with the drug for 2 days. DA addition to the incubation media decreased the in vitro release of PRL, GH and LH from the in situ pituitaries of sham-operated and pituitary-grafted animals treated with vehicle. In CyA treated animals, DA decreased in vitro PRL release from the in situ pituitaries of animals, independently of the presence or absence of an ectopic pituitary. Reductions of the in vitro GH and LH release release after DA treatment were higher in the in situ pituitaries from grafted animals on day 8 of CyA or vehicle treatment. TRH increased the in vitro release of the three hormones with differential effects related to the length of the treatment with CyA and/or the presence of an ectopic pituitary. In vitro release of PRL and GH by ectopic pituitaries was inhibited by previous treatment with CyA and this effect was decreased proportional to the duration of the treatment with the drug, while LH secretion was not modified. Addition of DA to the incubation media resulted in a marked reduction of in vitro PRL and GH release, but only at day 8 of vehicle treatment on GH release did DA addition to media further decrease the release of both hormones from ectopic pituitaries from animals treated for 2 or 8 days with the drug, whereas LH secretion was not modified. TRH addition to the incubation media of ectopic pituitaries surprisingly reduced PRL and GH secretion on day 8 of CyA treatment or after surgery. The results of these studies suggest that CyA can act directly at the hypophyseal level modifying pituitary responsiveness to external...

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 73%

Section: Drug Treatment and Samplingmentioning

confidence: 99%

Section: Drug Treatment and Samplingmentioning

confidence: 99%

See 2 more Smart Citations

Cyclosporine Effects on in vitro Responsiveness of Anterior Pituitary Hormone Release to Dopamine and Thyrotropin‐Releasing Hormone in Young Female Rats

Arce

et al. 1995

J Neuroendocrinology

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“…The results are given as nanograms per millili ter of serum; the standards employed were those supplied with the kits (PRL-RP-3 and GH-RP-2, respectively). Intra-and interassay coefficients of variation were 5 and 10% (GH) [11] and 6 and 9% (PRL) [12]. MBH GRH.…”

Section: Methodsmentioning

confidence: 99%

Changes in Serum Growth Hormone and Prolactin Levels, and in Hypothalamic Growth Hormone-Releasing Hormone, Thyrotropin-Releasing Hormone and Somatostatin Content, after Superior Cervical Sympathectomy in Rats

Cardinali

Esquifino²,

Arce³

et al. 1994

Neuroendocrinology

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After bilateral superior cervical ganglionectomy (SCGx) of adult male rats, norepinephrine (NE) content of the medial basal hypothalamus (MBH) decreased significantly by 39-47% from 16 h to 7 days after surgery. During this time the levels of serum growth hormone (GH) and prolactin (PRL) and of MBH GH-releasing hormone (GRH), thyrotropin-releasing hormone (TRH) and somatostatin were measured by RIA. In sham-operated controls, serum PRL increased and serum GH decreased 16–24 h after surgery, attaining pre-surgical levels later on. In SCGx rats, significantly lower serum GH and PRL and higher MBH GRH and TRH content as compared to controls was observed 16-24 h after surgery, during the wallerian degeneration phase after SCGx. MBH somatostatin concentration decreased in SCGx rats 20 h after surgery. Two injections of the α₁-adrenoceptor blocker prazosin 45 and 90 min before sacrifice, alone or together with the β-blocker propranolol, prevented the changes in MBH hypophysiotropic hormone content, as well as in serum GH and PRL levels, found in SCGx rats 20 h after surgery. Propranolol treatment did not affect hormone levels. Neither drug modified the decrease in MBH NE content observed after SCGx. The results argue in favor of the existence of physiologically relevant projections from superior cervical ganglion neurons to the MBH controlling hypophysiotropic hormone release.

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Pituitary cell transplantation

Chen

Mohr

1996

Yearbook of Cell and Tissue Transplantation 1996–1997

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Regulation of GH and TSH release from hyperplastic and ectopic pituitaries: Effects of dopamine in vitro

Cited by 8 publications

References 26 publications

Cyclosporine Effects on in vitro Responsiveness of Anterior Pituitary Hormone Release to Dopamine and Thyrotropin‐Releasing Hormone in Young Female Rats

Cyclosporine Effects on in vitro Responsiveness of Anterior Pituitary Hormone Release to Dopamine and Thyrotropin‐Releasing Hormone in Young Female Rats

Changes in Serum Growth Hormone and Prolactin Levels, and in Hypothalamic Growth Hormone-Releasing Hormone, Thyrotropin-Releasing Hormone and Somatostatin Content, after Superior Cervical Sympathectomy in Rats

Pituitary cell transplantation

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