Ghrelin does not regulate the GH response to insulin-induced hypoglycaemia in children but could be involved in the regulation of cortisol secretion.
OBJECTIVE
Ghrelin activates the growth hormone secretagogue receptor GHS-R. It strongly stimulates GH secretion and has a role in energy homeostasis. The relationship between plasma ghrelin and cortisol levels during insulin-induced hypoglycaemia in prepubertal and pubertal children has not yet been investigated. The aim of the present study was to establish whether insulin-induced hypoglycaemia stimulates ghrelin secretion and whether changes in ghrelin concentrations are related to changes in GH and cortisol in children.


METHODS
We studied a group of 20 children and adolescents (five girls, 15 boys, mean age 10.8 +/- 3.7 years) undergoing insulin tolerance tests (ITTs) for clinical investigation of GH deficiency.


METHODS
Stimulation tests were performed to investigate the relationship between ghrelin, GH, cortisol and glucose levels according to age and pubertal stage by determining the ghrelin profiles during insulin-induced hypoglycaemia (at 0, 60 and 120 min).


RESULTS
Ghrelin was significantly and inversely related to body weight, height, body mass index (BMI) and age of children (P < 0.05). Significant changes in ghrelin levels (P = 0.00013) were found after the insulin bolus, with a decline at 60 min and an increase to baseline values at 120 min. Changes in cortisol levels were negatively correlated with changes in ghrelin at 60 min (r = -0.59, P = 0.004) and at 120 min (r = -0.605, P = 0.003).


CONCLUSIONS
This study shows that ghrelin might not regulate the GH response to insulin-induced hypoglycaemia in prepubertal and pubertal children. A role for ghrelin in the regulation of cortisol secretion can be hypothesized concerning the negative correlation between changes in ghrelin and cortisol. Furthermore, the results imply that ghrelin secretion is age dependent and is a function of growth.
Huber
J
J
Department of Paediatrics, Division of Endocrinology and Diabetes, Medical University Graz, Austria.
Reiterer
E E
EE
Sudi
K
K
Gallistl
S
S
Friedl
K
K
Weinhandl
G
G
Aigner
R
R
Borkenstein
M H
MH
D000293:Adolescent; D000367:Age Factors; D000704:Analysis of Variance; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D005260:Female; D054439:Ghrelin; D006130:Growth Disorders / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology; D013006:Growth Hormone / Q000097:blood / Q000172:deficiency*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007003:Hypoglycemia / Q000097:blood*; D007004:Hypoglycemic Agents; D007328:Insulin; D008297:Male; D036361:Peptide Hormones / Q000097:blood*; D013997:Time Factors
D054439:Ghrelin; D007004:Hypoglycemic Agents; D007328:Insulin; D036361:Peptide Hormones; D013006:Growth Hormone; D006854:Hydrocortisone