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Comment |
Fox MD, et al reported that galanin is a novel intraovarian regulatory peptide.
To study possible ovarian
expression and regulation of galanin, immature gonadotropin-primed rats were
given hCG (10 IU), and their ovaries were collected 0, 4, 8, 12, and 20 h after
hCG treatment for determination of galanin messenger RNA (mRNA)
concentration by solution hybridization. Galanin mRNA levels progressively
increased after hCG administration, peaking at 12 h (2.4-fold increase vs. 0 h),
with a subsequent return to 0 h levels at 20 h. To determine a possible ovarian
role for galanin, rats were killed 48 h after gonadotropin administration, their
ovaries were removed, and granulosa cells were harvested. These cells and the
ovarian tissue remaining after granulosa cell collection (i.e. "shells") were each
cultured for 24 h with increasing concentrations of galanin (0, 10, 100, and 1000
nM) in the presence or absence of LH. The medium was examined for steroid
production and metalloproteinase inhibitor activity. In granulosa cell cultures,
galanin increased the levels of estradiol by 26% and had no effect on
progesterone, but decreased metalloproteinase inhibitor activity by 61% in the
conditioned medium. In the shell cultures, galanin increased estradiol,
progesterone, and androstenedione in the medium, suggesting that galanin acts on
cells other than granulosa cells or that galanin action requires a paracrine
interaction between granulosa and thecal cells.
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