Abstract
We have studied the in vitro TSH secretion and the adenylate cyclase (AC) activity of a human pituitary adenoma surgically removed from a hyperthyroid patient showing high serum TSH levels. The tumor appeared almost homogeneously constituted by cells positive for an anti-TSH-beta antiserum and showing the ultrastructural characteristics of the adenomatous thyrotrophs. Adenoma fragments released in vitro a large amount of TSH (148.4 μU/mg prot/30 min), alpha-subunit(35.5 ng/mg prot/30 min) and TSH-beta (10.1 ng/mg prot/30 min). The effects of somatostatin (GHRIH) and dopamine (DA) on the hormone release have been tested in vitro. Both agents markedly inhibited the release of intact TSH and TSH-beta whereas the release of alpha-subunit was less affected. The two agents were effective at concentrations higher than 10−8M. The ability of GHRIH and DA in modulating the AC activity was investigated in membrane fraction preparations. GHRIH inhibited AC at concentrations higher than 10 −7M. The maximal inhibition was 32% at 10−5 M. Conversely, DA slightly stimulated AC activity. This effects was not mimicked by the dopaminergic ergot CH 29–717, which was completely ineffective on the enzyme. These results suggest that: 1) in this TSH-secreting pituitary adenoma a normal secretory response to the inhibiting agents (GHRIH and DA) is present; 2) different mechanisms of transduction of the GHRIH and DA signals (cAMP dependent and cAMP independent) could be operating in this tumor.
| Original language | English |
|---|---|
| Pages (from-to) | 193-198 |
| Number of pages | 6 |
| Journal | Journal of Endocrinological Investigation |
| Volume | 8 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - 1985 |
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Keywords
- adenylate cyclase
- dopamine
- pituitary adenomas
- somatostatin
- TSH
ASJC Scopus subject areas
- Endocrinology
- Endocrinology, Diabetes and Metabolism
Cite this
In vitro studies on TSH secretion and adenylate cyclase activity in a human TSH-secreting pituitary adenoma. Effects of somatostatin and dopamine. / Spada, A.; Bassetti, M.; Martino, E.; Giannattasio, G.; Beck-Peccoz, P.; Sartorio, A.; Vallar, L.; Baschieri, L.; Pinchera, A.; Faglia, G.
In: Journal of Endocrinological Investigation, Vol. 8, No. 3, 1985, p. 193-198.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - In vitro studies on TSH secretion and adenylate cyclase activity in a human TSH-secreting pituitary adenoma. Effects of somatostatin and dopamine
AU - Spada, A.
AU - Bassetti, M.
AU - Martino, E.
AU - Giannattasio, G.
AU - Beck-Peccoz, P.
AU - Sartorio, A.
AU - Vallar, L.
AU - Baschieri, L.
AU - Pinchera, A.
AU - Faglia, G.
PY - 1985
Y1 - 1985
N2 - We have studied the in vitro TSH secretion and the adenylate cyclase (AC) activity of a human pituitary adenoma surgically removed from a hyperthyroid patient showing high serum TSH levels. The tumor appeared almost homogeneously constituted by cells positive for an anti-TSH-beta antiserum and showing the ultrastructural characteristics of the adenomatous thyrotrophs. Adenoma fragments released in vitro a large amount of TSH (148.4 μU/mg prot/30 min), alpha-subunit(35.5 ng/mg prot/30 min) and TSH-beta (10.1 ng/mg prot/30 min). The effects of somatostatin (GHRIH) and dopamine (DA) on the hormone release have been tested in vitro. Both agents markedly inhibited the release of intact TSH and TSH-beta whereas the release of alpha-subunit was less affected. The two agents were effective at concentrations higher than 10−8M. The ability of GHRIH and DA in modulating the AC activity was investigated in membrane fraction preparations. GHRIH inhibited AC at concentrations higher than 10 −7M. The maximal inhibition was 32% at 10−5 M. Conversely, DA slightly stimulated AC activity. This effects was not mimicked by the dopaminergic ergot CH 29–717, which was completely ineffective on the enzyme. These results suggest that: 1) in this TSH-secreting pituitary adenoma a normal secretory response to the inhibiting agents (GHRIH and DA) is present; 2) different mechanisms of transduction of the GHRIH and DA signals (cAMP dependent and cAMP independent) could be operating in this tumor.
AB - We have studied the in vitro TSH secretion and the adenylate cyclase (AC) activity of a human pituitary adenoma surgically removed from a hyperthyroid patient showing high serum TSH levels. The tumor appeared almost homogeneously constituted by cells positive for an anti-TSH-beta antiserum and showing the ultrastructural characteristics of the adenomatous thyrotrophs. Adenoma fragments released in vitro a large amount of TSH (148.4 μU/mg prot/30 min), alpha-subunit(35.5 ng/mg prot/30 min) and TSH-beta (10.1 ng/mg prot/30 min). The effects of somatostatin (GHRIH) and dopamine (DA) on the hormone release have been tested in vitro. Both agents markedly inhibited the release of intact TSH and TSH-beta whereas the release of alpha-subunit was less affected. The two agents were effective at concentrations higher than 10−8M. The ability of GHRIH and DA in modulating the AC activity was investigated in membrane fraction preparations. GHRIH inhibited AC at concentrations higher than 10 −7M. The maximal inhibition was 32% at 10−5 M. Conversely, DA slightly stimulated AC activity. This effects was not mimicked by the dopaminergic ergot CH 29–717, which was completely ineffective on the enzyme. These results suggest that: 1) in this TSH-secreting pituitary adenoma a normal secretory response to the inhibiting agents (GHRIH and DA) is present; 2) different mechanisms of transduction of the GHRIH and DA signals (cAMP dependent and cAMP independent) could be operating in this tumor.
KW - adenylate cyclase
KW - dopamine
KW - pituitary adenomas
KW - somatostatin
KW - TSH
UR - http://www.scopus.com/inward/record.url?scp=0021873515&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0021873515&partnerID=8YFLogxK
U2 - 10.1007/BF03348476
DO - 10.1007/BF03348476
M3 - Article
VL - 8
SP - 193
EP - 198
JO - Journal of Endocrinological Investigation
JF - Journal of Endocrinological Investigation
SN - 0391-4097
IS - 3
ER -