Vol. 278, Issue 6, E1060-E1066, June 2000
The differential effects of galanin-(1
30) and -(330) on
anterior pituitary hormone secretion in vivo in humans
Jeannie F.
Todd,
C. Mark B.
Edwards,
Mohammad A.
Ghatei, and
Stephen R.
Bloom
Endocrine Unit, Imperial College of Science, Technology and
Medicine Hammersmith Hospital, London W12 ONN, United
Kingdom
Intravenous
injection of galanin increases plasma growth hormone (GH) and prolactin
(PRL) concentrations. In the rat, the effects of galanin on GH appear
to be mediated via the hypothalamic galanin receptor
GAL-R1, at which galanin-(3
29) is inactive. In contrast,
the effect of galanin on PRL is mediated via the pituitary-specific
galanin receptor GAL-RW, at which galanin-(329) is fully
active. We investigated the effects of an intravenous infusion of human
galanin (hGAL)-(130) and -(330) on anterior pituitary hormone
levels in healthy females. Subjects were infused with saline,
hGAL-(130) (80 pmol · kg
1 · min1),
and hGAL-(330) (600 pmol · kg1 · min1)
and with boluses of gonadotropin-releasing hormone,
thyrotropin-releasing hormone, and growth hormone-releasing hormone
(GHRH). Both hGAL-(130) and -(330) potentiated the rise in
GHRH-stimulated GH levels [area under the curve (AUC), saline,
2,810 ± 500 vs. hGAL-(130), 4,660 ± 737, P < 0.01; vs.
hGAL-(330), 6,870 ± 1,550 ng · min · ml1,
P < 0.01]. In contrast to hGAL-(130), hGAL-(330)
had no effect on basal GH levels (AUC, saline, 
110 ± 88 vs. hGAL 130, 960 ± 280, P < 0.002; vs.
hGAL-(330), 110 ± 54 ng · min · ml1,
P = not significant). These data suggest that the
effects of galanin on basal and stimulated GH release are mediated via
different receptor subtypes and that the human equivalent of
GAL-RW may exist.
infusion; growth hormone; prolactin; pituitary function test
