Onset of synthesis of progesterone by ovine placenta

Previously, progesterone was found to regulate the initiation and biosynthetic rate of myelin synthesis in Schwann cell/neuronal cocultures. The mRNA for cytochrome P450scc (converts cholesterol to pregnenolone), 3β-hydroxysteroid dehydrogenase (3β-HSD, converts pregnenolone to progesterone), and the progesterone receptor were found to be markedly induced during active myelin synthesis. However, the cells in the cocultures responsible for these changes were not identified. In this study, in situ hybridization was used to determine the localization of the enzymes responsible for steroid biosynthesis. The mRNA for cytochrome P450scc and 3β-HSD were detected only in actively myelinating cocultures and were localized exclusively in the Schwann cells. Using immunocytochemistry, with minimal staining of the Schwann cells, we found the progesterone receptor in the dorsal root ganglia (DRG) neurons. The progesterone receptor in the neurons translocated into the nuclei of these cells when progesterone was added to neuronal cultures or during myelin synthesis in the cocultures. Additionally, a marked induction of the progesterone receptor was found in neuronal cultures after the addition of progesterone. The induction of various genes in the neurons was also investigated using mRNA differential display PCR in an attempt to elucidate the mechanism of steroid action on myelin synthesis. Two novel genes were induced in neuronal cultures by progesterone. These genes, along with the progesterone receptor, were also induced in cocultures during myelin synthesis, and their induction was blocked by RU-486 (a progesterone receptor antagonist). These genes were not induced in Schwann cells cultured alone after the addition of progesterone. These results suggest that progesterone is synthesized in Schwann cells and that it can indirectly regulate myelin formation by activating transcription via the classical steroid receptor in the DRG neurons.


the local synthesis of progesterone plays an important role in the formation of myelin sheaths.

Synthesis of Progesterone and Estradiol by Monkey …

As a control, differential display was also conducted on Schwann cell cultures with and without the addition of progesterone. In contrast to the results with the neurons, no bands were identified as being induced with progesterone, and the results suggest that progesterone has a little effect on Schwann cell transcription. Using RT-PCR, Rap 1b and PRPP synthase-associated protein were detected in Schwann cell cultures, but they were not induced by progesterone. This also means that the induction (fold-change) of the genes in the neurons observed in the cocultures (Table ) was underestimated due to the constitutive levels of Rap 1b and PRPP synthase-associated protein in Schwann cells. In addition, progesterone added to Schwann cell cultures also did not show an induction in the mRNA for MBP, the progesterone receptor, or the myosin light chain.

as a chemical precursor for the industrial synthesis of progesterone

To elucidate the specific genes induced by progesterone in neuronal cells, differential display was applied to the mRNA from neuronal cultures (no Schwann cells) with and without the addition of progesterone (100 nM). The progesterone receptor was auto-induced by progesterone, and differential display identified four additional genes, two of which were induced by progesterone and inhibited by RU-486 in cocultures (Table ). These two genes are Rap 1b (a small Ras-like GTP-binding protein) and PRPP (phosphoribosyl diphosphate) synthase-associated protein. The third gene, nonmuscle myosin light chain, was not induced in the neurons with progesterone, in cocultures during myelin synthesis, nor was it effected by RU-486 in cocultures. Therefore, the myosin light chain most likely represents a false positive from the differential display PCR and is not directly related to myelin synthesis. The fourth gene was in the database (rat ovary cDNA clone #ROVAA30), but its identity is not known. A total of ten different genes were isolated using differential display on neuronal cultures with and without progesterone, but only four of the ten genes were identified in the GenBank/EMBL database.

Natural Progesterone Oil | Progest E Complex

Steroid hormones have dramatic and widespread effects on the central and peripheral nervous systems. The biosynthesis and interactions of steroids in the rat brain and spinal cord independent of steroidogenic gland secretion have been well-documented (; ; ). We have shown that endogenously synthesized steroids in Schwann cell/neuronal cocultures affect the initiation and regulate the biosynthetic rate of myelin synthesis (). Progesterone may be synthesized in either Schwann cells or neurons and may act as signaling molecules in the formation of myelin. Therefore, the localization of cytochrome P450scc and 3β-HSD expression are essential in elucidating the mechanism of steroid hormone signaling during myelin synthesis. Using premyelinating and myelinating cocultures, the induced expression of the mRNA for cytochrome P450scc and 3β-HSD was localized exclusively to the Schwann cells. Furthermore, this expression was limited to the period of myelin synthesis.

A hydroxy or hydroxyl group is the entity with the formula OH

Besides the translocation of the receptor in neurons, the immunocytochemical staining suggested an overall induction of the receptor in the presence of progesterone. Using RT-PCR as described previously, a dramatic auto-induction of the progesterone receptor was observed in neuronal cultures (Figure A). Furthermore, to investigate the mechanism of the progesterone receptor in myelin synthesis, the mRNA from premyelinating and myelinating cocultures were extracted, as well as corresponding cocultures after the addition of RU-486 (100 nM, a progesterone receptor antagonist). Previously, the progesterone receptor mRNA was found to be induced by 10-fold during active myelin synthesis in cocultures (). Upon addition of RU-486, the induction was completely abolished in the cocultures (Figure B). RU-486 was also found to inhibit the induction of MBP in the cocultures, consistent with its inhibition of myelin synthesis (; ). The addition of progesterone or RU-486 to Schwann cell cultures did not result in detectable quantities of the progesterone receptor mRNA.

Progesterone and PCOS - What You Need to Know

In bitches that experience pseudopregnancy, the corpus luteum does not regress despitethe fact that conception has not taken place. As a result, increased progesterone levelsare maintained bringing about the signs consistent with pregnancy. Around day 60,progesterone levels will abruptly drop as is observed at the end of gestation in pregnantbitches. This drop in progesterone results in elevation of the hormone prolactin, which isresponsible for the typical nesting-behavior in pregnant bitches. As such, thepseudopregnant bitch will display the same behavior as a bitch that is actually pregnant.