Zinc and bromocriptine long-term administration in patients with prolactinomas: effects on prolactin and thymulin circulating levels.
Several studies have demonstrated zinc (Zn), prolactin (PRL) and thymulin (Zn-FTS) interplay: Zn inhibits, in a dose related manner, PRL release from lactotropes in vitro and stimulates thymulin synthesis in vivo both in humans and in animals. PRL receptors are present on thymic epithelial cells (TEC); PRL stimulates TEC trophism and activity. Little is known about the influence of PRL on Zn metabolism, though in prolactinomas we found reduced Zn and thymulin circulating levels. For this reason, we evaluated PRL, Zn, bioactive thymulin (Zn-FTS) and total thymulin (T-FTS: Zn-bound plus Zn-unbound form) serum levels in 58 patients with prolactinomas (PRL: 253 +/- 263 micrograms/L), Zn (82 +/- 23 micrograms/dl), Zn-FTS (2.2 +/- 0.20 log2(-1] and T-FTS (3.7 +/- 0.25 log2(-1] were significantly lower (p less than .01) than those found in age matched controls. Zn-unbound bioinactive thymulin form (FTS) levels were in the normal range. Bromocriptine administration (Brc) (2.5-5 mg p.o., b.i.d. for 9 months) to 20 patients with microprolactinomas lowered serum PRL levels (10.5 +/- 6.2 micrograms/L) and significantly increased (p less than .01) Zn (118.6 +/- 14.7 micrograms/dl), Zn-FTS (3.96 +/- 0.7 log2(-1)) and T-FTS (4.66 +/- 0.7 log2(1)) circulating levels. ZnSO4 administration (400 mg p.o. daily for 3 months) to 6 patients with microprolactinomas, significantly increased (p less than .01) Zn (136 +/- 18 micrograms/dl), Zn-FTS (4.5 +/- 0.5 log2(-1)) and T-FTS (5.6 +/- 0.9 log2(-1)) levels, while caused only a slight decrease in serum PRL concentrations (from 95 +/- 8 to 75 +/- 9 micrograms/L; p: NS).(ABSTRACT TRUNCATED AT 250 WORDS)
Travaglini
P
P
Institute of Endocrine Sciences, University of Milan, Italy.
Mocchegiani
E
E
De Min
C
C
Re
T
T
Fabris
N
N
Faglia
G
G
D000328:Adult; D001971:Bromocriptine / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D010911:Pituitary Neoplasms / Q000378:metabolism*; D011388:Prolactin / Q000097:blood*; D015175:Prolactinoma / Q000378:metabolism*; D011863:Radioimmunoassay; D013935:Thymic Factor, Circulating / Q000378:metabolism*; D015032:Zinc / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*
D001971:Bromocriptine; D011388:Prolactin; D013935:Thymic Factor, Circulating; D015032:Zinc