Ghrelin administration affects circulating pituitary and gastro-entero-pancreatic hormones in acromegaly.
OBJECTIVE
Ghrelin, a gut-brain peptide involved in the control of energy homeostasis, affects antero-pituitary and gastro-entero-pancreatic (GEP) hormone secretion in healthy subjects. We aimed to verify whether such hormonal responses are retained in acromegaly, a disease characterized by high GH, subnormal ghrelin and abnormal GEP hormone levels.


METHODS
The effect of ghrelin (3.3 microg/kg given after overnight fasting as an i.v. bolus) on GH, prolactin (PRL), adrenocorticotropin (ACTH), cortisol, insulin, glucose, total somatostatin (SS) and pancreatic polypeptide (PP) circulating levels were evaluated in seven non-diabetic patients with newly diagnosed acromegaly and in nine healthy controls.


RESULTS
Ghrelin elicited a prompt, marked increase of serum GH and PRL levels in all normal (from 1.6+/-0.6 to 52.9+/-7.8 and from 9.7+/-0.8 to 24.2+/-4.8 microg/l (means+/-S.E.M.), respectively) and acromegalic subjects (from 11.2+/-4.9 to 91.6+/-21.0 and from 42.9+/-26.1 to 113.8+/-79.0 microg/l, respectively). Both plasma ACTH and serum cortisol levels rose significantly in the controls, whereas the cortisol response was blunted in the acromegalic patients. Glucose levels rose earlier and insulin levels fell later in all subjects, with a significantly greater net insulin decrease in acromegalic than in healthy subjects (-80+/-21 vs -17+/-4 pmol/l, P<0.01). A prompt PP rise and a biphasic SS response occurred in all controls, whereas in the acromegalic group the PP response (from 26.1+/-5.0 to 92.2+/-39.0 pmol/l) and the SS response (from 11.9+/-3.0 to 19.7+/-4.0 ng/l) were quite variable.


CONCLUSIONS
Ghrelin affects both pituitary and GEP hormones in acromegalic patients as in normal subjects. These findings suggest that ghrelin actions on the energy balance are mediated by complex interactive endocrine loops that involve also the gut and pancreas.
Arosio
M
M
Institute of Endocrine Sciences, University of Milan, Ospedale Maggiore IRCCS, via F Sforza, 35, Milan, Italy. maura.arosio@unimi.it
Ronchi
C L
CL
Gebbia
C
C
Pizzinelli
S
S
Conte
D
D
Cappiello
V
V
Epaminonda
P
P
Cesana
B M
BM
Beck-Peccoz
P
P
Peracchi
M
M
D000172:Acromegaly / Q000097:blood* / Q000188:drug therapy*; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D000368:Aged; D001786:Blood Glucose; D005260:Female; D054439:Ghrelin; D006728:Hormones / Q000097:blood*; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D010179:Pancreas / Q000378:metabolism; D010191:Pancreatic Polypeptide / Q000097:blood; D036361:Peptide Hormones / Q000008:administration & dosage*; D010902:Pituitary Gland / Q000378:metabolism; D011388:Prolactin / Q000097:blood; D013004:Somatostatin / Q000097:blood
D001786:Blood Glucose; D054439:Ghrelin; D006728:Hormones; D007328:Insulin; D036361:Peptide Hormones; D019382:Human Growth Hormone; D013004:Somatostatin; D010191:Pancreatic Polypeptide; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D006854:Hydrocortisone