Changes in serum insulin-like factor 3 during normal male puberty.
BACKGROUND
Insulin-like factor 3 (INSL3) is produced by the Leydig cells, and in adults, its secretion is dependent on the state of differentiation of these cells, which, in turn, is dependent on LH. However, the secretion and regulation of INSL3 during puberty is unknown.


OBJECTIVE
Our objective was to evaluate INSL3 concentrations during normal male puberty and the relation of INSL3 to LH, FSH, and testosterone.


METHODS
We conducted a cross-sectional study from January to December 2005 at academic clinics.


METHODS
Participating in the study were 75 healthy male subjects aged 9.5-17.5 yr, homogeneously distributed into five pubertal groups of 15 according to Tanner stages.


METHODS
We assessed mean testicular volume and LH, FSH, testosterone, and INSL3 concentrations in relation to age and pubertal stage.


RESULTS
We observed an increase of INSL3 and LH levels from Tanner stage 2 to 4, and an increase of FSH from stage 2 to 3. Testosterone levels increased from stage 3 to 4. No differences were seen for all measured hormones between stages 4 and 5. The increase in INSL3 seemed therefore to anticipate the increase in testosterone. However, INSL3 plasma concentrations at pubertal stages 4 and 5 are about one fourth of adult levels, whereas FSH, LH, and testosterone reached adult levels by stage 4. Positive significant correlations were found between INSL3 and LH for all pubertal stages.


CONCLUSIONS
This study provides information on the physiological dynamics of INSL3, showing that the serum concentrations of this hormone increased progressively throughout puberty under the differentiating action of LH on Leydig cells. INSL3 is therefore confirmed to represent a marker of Leydig cell differentiation and function. However, a prolonged exposure to LH seems to be necessary to reach INSL3 concentrations of adults. A possible use of INSL3 in puberty disorders is promising.
Ferlin
Alberto
A
University of Padova, Department of Histology, Microbiology and Medical Biotechnologies, Centre for Male Gamete Cryopreservation, Via Gabelli 63, 35121 Padova, Italy.
Garolla
Andrea
A
Rigon
Franco
F
Rasi Caldogno
Lucia
L
Lenzi
Andrea
A
Foresta
Carlo
C
D000293:Adolescent; D000367:Age Factors; D002648:Child; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood*; D007985:Leydig Cells / Q000378:metabolism; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D011506:Proteins; D011627:Puberty / Q000097:blood*; D018709:Statistics, Nonparametric; D013737:Testis / Q000378:metabolism; D013739:Testosterone / Q000097:blood / Q000378:metabolism
D007328:Insulin; C084797:Leydig insulin-like protein; D011506:Proteins; D013739:Testosterone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone