hexarelin and Adenoma

hexarelin has been researched along with Adenoma* in 5 studies

Reviews

1 review(s) available for hexarelin and Adenoma

ArticleYear
Biochemical and imaging evaluation of Cushing's syndrome.
    Minerva endocrinologica, 2002, Volume: 27, Issue:2

    The diagnosis and differential diagnosis of Cushing's syndrome remains a considerable challenge in clinical endocrinology. Investigation is a two-step process, involving first diagnosis followed by differential diagnosis. Traditionally diagnosis has relied upon urinary free cortisol (UFC) collection, low-dose dexamethasone-testing, and assessment of midnight cortisol. More recently, differentiation between mild disease and pseudo-Cushing's states has been achieved using dexamethasone-suppressed corticotropin releasing hormone (CRH) and desmopressin tests. Refinements of tests used for differential diagnosis have been made including optimized response criteria for ovine and human sequence CRH tests, desmopressin tests, GHBP-testing and testing with combinations of peptides. Despite improvements in these non-invasive tests use of inferior petrosal or cavernous sinus sampling is frequently required. Imaging is guided by biochemical assessment. MRI is the investigation of choice for Cushing's disease, but is often negative. Scintigraphic investigation using radionucleotide-labeled agonists for receptors commonly expressed by neuroendocrine tumors the investigation of occult ACTH-dependent disease remains disappointing. In this review we critically analyze the tests used for this most challenging of clinical conditions.

    Topics: ACTH Syndrome, Ectopic; Adenoma; Adrenal Cortex Neoplasms; Adrenocorticotropic Hormone; Animals; Arginine Vasopressin; Circadian Rhythm; Corticotropin-Releasing Hormone; Cushing Syndrome; Deamino Arginine Vasopressin; Dexamethasone; Diagnosis, Differential; Humans; Hydrocortisone; Hypothalamo-Hypophyseal System; Magnetic Resonance Imaging; Oligopeptides; Petrosal Sinus Sampling; Pituitary Neoplasms; Pituitary-Adrenal System; Radiography; Radionuclide Imaging; Sheep

2002

Trials

1 trial(s) available for hexarelin and Adenoma

ArticleYear
Adrenocorticotropin and cortisol hyperresponsiveness to hexarelin in patients with Cushing's disease bearing a pituitary microadenoma, but not in those with macroadenoma.
    The Journal of clinical endocrinology and metabolism, 1998, Volume: 83, Issue:12

    We previously reported that in Cushing's disease (CD) the ACTH- and cortisol (F)-releasing activity of Hexarelin (HEX), a GH secretagogue, is exaggerated with respect to that in normal subjects and is higher than that of human CRH (hCRH), but it is absent in Cushing's syndrome. Our aim was to extend the study about the effects of HEX (2.0 microg/kg, iv) on ACTH and F secretion in 21 patients with CD (3 men and 18 women, 16-68 yr old). Based on magnetic resonance imaging, 15 CD patients had pituitary microadenoma, and 6 had macroadenoma. The results in CD patients were compared with those in 27 normal age-matched controls (NS; 10 men and 17 women, 24-69 yr old). Basal ACTH and F levels in CD were similar in patients with microadenom (mean+/-SEM, 78.3+/-7.2 pg/mL and 237.1+/-23.6 microg/L, respectively) and macroadenoma (57.4+/-9.0 pg/mL and 196.9+/-20.1 microg/L, respectively) and were higher (P < 0.001) than those in NS (17.7+/-2.0 pg/mL and 115.3+/-6.7 microg/L, respectively). In microadenoma CD patients, HEX induced marked ACTH and F increases (delta peak, mean+/-SEM: 261.2+/-77.6 pg/mL and 226.1+/-87.2 microg/L, respectively), which were higher (P < 0.04) than those induced by hCRH (45.6+/-16.9 pg/mL and 84.6+/-25.7 microg/L, respectively). Moreover, in microadenoma CD patients, the ACTH and F responses to HEX were higher (P < 0.001) than those in NS (18.5+/-4.0 pg/mL and 36.1+/-6.8 microg/L, respectively). In macroadenoma CD patients, HEX induced a slight, but significant increase (P < 0.02) in ACTH and F levels (33.9+/-18.0 pg/mL and 89.6+/-34.3 microg/L, respectively), which was not significantly different from that elicited by hCRH (20.0+/-7.0 pg/mL and 54.8+/-21.3 microg/L, respectively). In macroadenoma CD patients, the ACTH and F responses to HEX and hCRH were, in turn, similar to those in NS. In conclusion, our findings demonstrate that the ACTH and F hyperresponsiveness to HEX is present in Cushing's disease with micro-, but not macro- ACTH-secreting pituitary adenoma. This finding agrees with other evidence pointing toward differences in the hormonal behavior between micro- and ACTH-secreting pituitary macroadenomas.

    Topics: Adenoma; Adolescent; Adrenocorticotropic Hormone; Adult; Aged; Corticotropin-Releasing Hormone; Cushing Syndrome; Female; Humans; Hydrocortisone; Male; Middle Aged; Oligopeptides; Pituitary Neoplasms; Reference Values

1998

Other Studies

3 other study(ies) available for hexarelin and Adenoma

ArticleYear
Interaction of the novel GH secretagogue hexarelin with GHRH in regulating the secretion of GH by cultured human pituitary somatotrophinomas in vitro.
    Journal of Tongji Medical University = Tong ji yi ke da xue xue bao, 2000, Volume: 20, Issue:2

    The effects of the novel GH-releasing hexapeptide, Hexarelin, on the secretion of GH in cultured human pituitary somatotrophinomas was further investigated. Hexarelin (20 nmol/L) strongly stimulated GH secretion, which could be reduced by phloretin, but not by RP-cAMPS, an inhibitor of protein kinase A (PKA). (Ac-Tyr1,D-Arg2)-GRF(1-29)-NH2 failed to block the effects of Hexarelin but completely abolished the stimulation of GH secretion exerted by GHRH. When added alone to somatotrophinoma cell cultures, Hexarelin had no effect on cAMP levels, but it potentiated the stimulatory effects of GHRH. These results demonstrated that Hexarelin could directly stimulate GH secretion by human pituitary somatotrophs PKC-dependently, which might be contributed to the activation of the PI transduction system. In addition, Hexarelin could interact with GHRH on the adenylyl cyclase system.

    Topics: Adenoma; Adenylyl Cyclases; Growth Hormone; Growth Hormone-Releasing Hormone; Humans; Oligopeptides; Pituitary Neoplasms; Tumor Cells, Cultured

2000
Effects of the novel GH secretogogue, hexarelin on GH secretion and phosphatidylinositol hydrolysis by human pituitary somatotrophinomas in cell culture.
    Journal of Tongji Medical University = Tong ji yi ke da xue xue bao, 1999, Volume: 19, Issue:3

    The effects of the novel GH-releasing hexapeptide, Hexarelin, on cultured human pituitary somatotrophinomas were investigated. Hexarelin (0.01-100 nmol/L) dose-dependently stimulated GH secretion up to 4.6-fold. Maximal effects occurred with 10 nmol/L. These effects were very similar to those observed with GHRP-6. The effects of Hexarelin were reduced by phloretin, an inhibitor of protein kinase C (PKC). The rate of phosphatidylinositol (PI) hydrolysis was markedly increased by Hexarelin in a dose-dependent manner. These results demonstrated that Hexarelin could directly stimulate GH secretion by human pituitary somatotrophs in a PKC-dependent manner, probably via activation of the PI transduction system.

    Topics: Adenoma; Dose-Response Relationship, Drug; Growth Hormone; Humans; Hydrolysis; Oligopeptides; Phosphatidylinositols; Pituitary Neoplasms; Tumor Cells, Cultured

1999
Reduction of the somatotrope responsiveness to GHRH and Hexarelin but not to arginine plus GHRH in hyperprolactinemic patients.
    Journal of endocrinological investigation, 1997, Volume: 20, Issue:10

    Aim of the present study was to verify the maximal secretory capacity of somatotrope cells in patients with pathological hyperprolactinemia (HPRL) comparing it with that in normal age-matched women (NW). To this goal in 12 HPRL normal weight patients (age 28.6 +/- 2.6 yr, BMI 23.1 +/- 1.1 kg/m2) and 8 NW (27.2 +/- 0.8 yr, 22.8 +/- 0.8 kg/m2) we studied the GH response to GHRH (1 microgram/kg i.v.), GHRH plus arginine (ARG, 0.5 g/kg i.v.), an amino acid probably acting at the hypothalamic level inhibiting somatostatin release, and Hexarelin (HEX, 2 micrograms/kg i.v.), a synthetic hexapeptide belonging to GHRP family, which acts concomitantly at the pituitary and the hypothalamic level. IGF-I levels in HPRL were similar to those in NW (179.2 +/- 16.5 micrograms/l and 218.5 +/- 30.8 micrograms/l). In NW the GH response to GHRH (AUC: 1299.5 +/- 186.9 micrograms 90 min/l) was lower (p < 0.02) than those to GHRH + ARG (5252.7 +/- 846.3 micrograms 90 min/l) and HEX 3216.6 +/- 462.3 micrograms 90 min/l) which, in turn, were similar. In HPRL the GH response to GHRH (894.7 +/- 242.4 micrograms 90 min/l) was lower (p < 0.03) than that to HEX (1586.5 +/- 251.3 micrograms 90 min/l) and both were lower (p < 0.03) than that to GHRH + ARG (4468.8 +/- 941.7 micrograms 90 min/l). In HPRL the GH responses to GHRH and HEX were lower than those that in NW (p < 0.03) while that to GHRH + ARG was similar in both groups. These results demonstrate that the somatotrope responsiveness to GHRH and HEX is clearly reduced in patients with pathological hyperprolactinemia. On the other hand, in this condition the GH response to GHRH + ARG is normal. As arginine likely acts via inhibition of hypothalamic somatostatin release, these findings show that the maximal secretory capacity of somatotrope cells in hyperprolactinemia is preserved and indicate that partial refractoriness of somatotrope cells to GHRH and HEX could be due to somatostatinergic hyperactivity.

    Topics: Adenoma; Adolescent; Adult; Arginine; Drug Interactions; Female; Growth Hormone-Releasing Hormone; Human Growth Hormone; Humans; Hyperprolactinemia; Hypothalamus; Oligopeptides; Pituitary Gland; Pituitary Neoplasms; Somatostatin

1997