Which studies by Alexander V. Sirotkin found melatonin suppresses progesterone and raises estrogen in pig tissue?

[marcuswhybrow]

In Thyroid Function with Gary Null Ray says the following:

But the function of melatonin all by itself, when it isn't surrounded by the appropriate other conditions, melatonin, in studies done in pig tissue, by a man named Sirotkin, pigs are relatively close to humans in having daytime habits, nighttime sleep and so on—which is very important for melatonin because it's a nighttime dominant hormone—in pigs, he found that melatonin suppresses progesterone and raises estrogen, and this happens to be the same thing that low thyroid does.

To which studies is Ray referring?

[marcuswhybrow]

Just by dumb searching, I've found these two studies:

1. Direct influence of melatonin on steroid, Nona peptide hormones, and cyclic nucleotide secretion by granulosa cells isolated from porcine ovaries
2. Direct regulation of mammalian reproductive organs by serotonin and melatonin