In vitro secretion of FSH by cultured clinically nonfunctioning and gonadotroph pituitary adenomas is directly correlated with locally produced levels of activin A
Ht. Wessels et al., In vitro secretion of FSH by cultured clinically nonfunctioning and gonadotroph pituitary adenomas is directly correlated with locally produced levels of activin A, CLIN ENDOCR, 54(4), 2001, pp. 485-492
OBJECTIVE Expression of mRNAs encoding activin and its antagonists inhibin
and follistatin has been described in human pituitary adenomas, including c
linically nonfunctioning adenomas (NFAs) and gonadotroph adenomas (Gn-omas)
. Since many of the NFAs and Gn-omas secrete FSH in vitro, we hypothesized
that locally produced activin may stimulate secretion of FSH in these pitui
tary adenomas.
PATIENTS and METHODS Pituitary adenoma tissue was obtained from 38 patients
diagnosed preoperatively as having NFAs (n = 17), Gn-omas (n = 5), prolact
inomas (n = 6) or growth hormone (GH) producing adenomas (n = 10), Actual p
rotein levels of activin, inhibin, follistatin, FSH and LH were measured in
media of these 38 cultured pituitary adenomas. In addition, we investigate
d correlations between concentrations of these growth factors and hormones
in NFAs and Gn-omas.
RESULTS Gn-omas were found to secrete significantly more activin A In their
culture medium than PRL- and GH-producing adenomas (P < 0.05). Inhibin A a
nd inhibin B protein levels in culture media were very low. A positive corr
elation between levels of activin A and FSH (r = 0.56, P < 0.005) was found
, while no correlation between activin A and LH could be detected. Furtherm
ore, levels of follistatin were positively correlated with activin A levels
(r = 0.73, P < 0.0005). Comparison of the activin A:follistatin ratio with
the measured FSH protein levels showed an evert stronger relationship (r =
0.79, P < 0.0005).
CONCLUSIONS It is concluded that revels of activin A, follistatin and FSH i
n media of cultured nonfunctioning adenomas and gonadotroph adenomas are po
sitively correlated. This suggests that these adenomas secrete FSH in respo
nse to the relatively high locally produced levels of activin A.