Steroids are biologically active compounds that contain four rings arranged in a specific molecular configuration. The rings in steroid compounds serve two primary biological functions: they act as signaling molecules and as important components of cell membranes. The ring structure of a steroid helps regulate the fluidity of cell membranes.
5a-DHP
5a-DHP is a metabolite of progesterone that is produced during pregnancy. It is produced in the endometrium. A study in Thoroughbred and pony mares found that the plasma levels of 5a-DHP increased from 63.7 ng/ml at 27 days before pregnancy to 161.7 ng/ml on the day of parturition.
5a-DHP synthesis is regulated by the SKF105,111 drug. Blocking 5a-reductase activity results in a reduction in the production of 5a-DHP and ALLO. Both 5a-DHP and ALLO are produced at a lower rate and thus, fail to saturate the 3a-HSOR.
This Joseph Baena is also reduced in group-housed and socially isolated mice. Systemic administration of 48 mmol/kg of SKF105,111 decreased 5a-DHP and ALLO content in the brain within 30 min. These concentrations remained low for 6 hours.
The down-regulation of 5a-DHP and ALLO is a long-term adaptation to social isolation. The effects of social isolation on 5a-DHP and ALLO levels have been noted in several independent studies. The down-regulation of ALLO may be due to the effects of stress.
This neuroactive steroid is thought to play an important role in regulating GABAergic transmission. It binds to the allosteric center of GABAA receptors, which facilitates the GABA-gating process. In addition, 5a-DHP regulates DNA transcription by binding to intracellular progesterone receptors.
Serum levels of 5a-DHP were monitored in 11 women during pregnancy. All of the samples were obtained from three to six times during labor and at one, three, and six hours after birth. It was found that serum levels of 5a-DHP decreased significantly before and during labor.
In mice, 5a-DHP decreases the level of ALLO in the frontal cortex and inhibits ALLO biosynthesis. Similarly, social isolation decreases the expression of 5a-DHP and PREG in the frontal cortex of mice. This suggests that these hormones play a role in regulating genes related to reproduction in the brain.
Lanosterol
Lanosterol is a naturally occurring steroid that is used to synthesize cholesterol and other steroid hormones. It is found in abundance in the crystalline lens of the eye. Researchers are testing the effects of lanosterol on human cataracts.
The tetracyclic triterpenoid lanosterol is one of the first steroid ring systems known. It is derived from lanosta-8,24-diene, and is the precursor to all other steroids. It has multiple roles in plant, animal, and bacterial metabolism.
Lanosterol is synthesized through the mevalonate pathway, which starts with acetyl-CoA as building blocks. From there, the compounds DMAPP and IPP are produced, which then form lanosterol. Further modification of this steroid is done through cyclization, which is a four-step process.
In vivo, lanosterol synthase metabolizes lanosterol to dihydrolanosterol. It plays a role in post-translational regulation of HMGCoA reductase, which is a key component of the meiotic process. The steroid is also a post-translational regulator of Insig, an ER-resident protein that interacts with the SREBP. Song and colleagues found that lanosterol enhanced Insig-mediated degradation of HMG-coa reductase. In addition, Lange and colleagues found that dihydrolanosterol inhibits HMGCoA reductase activity. Thus, lanosterol is a potential target for drug development.
Scientists have been studying whether lanosterol can reduce the incidence of cataracts. In recent studies, the drug is effective in treating the disease. The study of dog and rabbit lenses suggests that lanosterol is more effective than lanosterol alone. The researchers also found that lanosterol increases the transparency of the lens proteins.
