Pregnenolone

About: Pregnenolone is a research topic. Over the lifetime, 3539 publications have been published within this topic receiving 126444 citations. The topic is also known as: (3b)-3-hydroxy-Pregn-5-en-20-one & 3-Hydroxypregn-5-en-20-one.

Pregnenolone sulfate antagonizes barbiturate-induced hypnosis

Abstract: The potential influence of the neurosteroid pregnenolone sulfate (PrS) on barbiturate-induced hypnosis was tested in rats. PrS, when injected intracerebroventricularly or intraperitoneally, significantly shortened the sleep-time produced by pentobarbital. The results suggest an important physiological and pharmacological role for PrS in the regulation of CNS excitability.

Plasma Levels of Gonadotropins, Prolactin, Thyroxine, and Adrenal and Gonadal Steroids in Obese Prepubertal Girls

Abstract: Plasma levels of gonadotropins, PRL, T4, and adrenal and gonadal steroids were measured in two groups of 7- to 9-yr-old and 10- to 11-yr-old obese prepubertal girls, and were compared to those found in groups of nonobese girls of the same age. The data found in normal weight subjects confirm the data reported in the literature, showing a significant rise between the 7- to 9- and 10- to 11-yr groups, of FSH, pregnenolone, dehydroepiandrosterone, testosterone, and estradiol plasma levels, while LH, PRL, T4, cortisol, progesterone, 17-hydroxyprogesterone (17P), and androstenedione remained constant. In the obese subjects, pregnenolone and dehydroepiandrosterone levels are notably higher than in the normal girls, in the same range as those found in adult women; furthermore, they show no rise between the two age groups. The obese prepubertal groups had significantly higher progesterone, androstenedione, and PRL levels in comparison with those observed in girls of normal weight, but 17- hydroxyprogesterone, cor...

Chrysin, a natural flavonoid enhances steroidogenesis and steroidogenic acute regulatory protein gene expression in mouse Leydig cells

Abstract: During the aging process of males, testosterone biosynthesis declines in testicular Leydig cells resulting in decreases in various physiological functions. To explore the possibility of delaying the decline using food supplements, we have studied steroidogenic effects of a natural flavonoid, chrysin, in mouse Leydig cells. Chrysin dramatically increased cyclic AMP (cAMP)-induced steroidogenesis in MA-10 mouse Leydig tumor cells. This result was confirmed using Leydig cells isolated from mouse testes. The steroidogenic effect of chrysin is not associated with an increase in expression of the P450 side-chain cleavage enzyme, required for the conversion of cholesterol to pregnenolone. In addition, when 22(R)hydroxylcholesterol was used as a substrate, chrysin induced a non-significant increase in steroid hormone, suggesting that the majority of the observed increase in steroidogenesis was due to the increased supply of substrate cholesterol. These observations were corroborated by showing that chrysin induced a marked increase in the expression of steroidogenic acute regulatory (StAR) protein, the factor that controls mitochondrial cholesterol transfer. Also, chrysin significantly increased StAR promoter activity and StAR mRNA level. Further studies indicated that this compound depressed expression of DAX-1, a repressor in StAR gene transcription. In the absence of cAMP, chrysin did not increase steroidogenesis. However, when a sub-threshold level of cAMP was used, StAR protein and steroid hormone were increased by chrysin to the levels seen with maximal stimulation of cAMP. These results suggest that while chrysin itself is unable to induce StAR gene expression and steroidogenesis, it appears to function by increasing the sensitivity of Leydig cells to cAMP stimulation.

Opposite effects of short- versus long-term administration of fluoxetine on the concentrations of neuroactive steroids in rat plasma and brain.

Abstract: Rationale: Recent preclinical and clinical studies have shown that selective serotonin re-uptake inhibitors modulate neurosteroid synthesis in an opposite manner. Objectives: The action of long-term administration of fluoxetine was investigated on the peripheral and central concentrations of 3α,5α-tetrahydroprogesterone (3α,5α-TH PROG) and 3α,5α-tetrahydrodeoxycorticosterone (of 3α,5α-TH DOC), progesterone, and pregnenolone in rats. We also investigated the effect of chronic treatment with fluoxetine on the foot-shock stress-induced increase in the plasma and brain concentrations of these steroids. Methods: Fluoxetine was administered acutely (20 mg/kg) or chronically (10 mg/kg, once daily for 15 days). Steroids were extracted from plasma and brain, separated and purified by means of high-performance liquid chromatography, and quantified by means of radioimmunoassay. Results: A single dose of fluoxetine (20 mg/kg, i.p.) induced in 20 min significant increases in the cerebral cortical and plasma concentrations of 3α,5α-TH PROG (+96% and +13%, respectively), 3α,5α-TH DOC (+129 and +31%, respectively), progesterone (+111 and +58%, respectively), and pregnenolone (+151 and +59%, respectively). In addition, the plasma concentration of corticosterone was also significantly increased (+24%) after acute administration of fluoxetine. In contrast, long-term administration of fluoxetine reduced the basal concentrations of these various steroids (ranging from –22 to –43%), measured 48 h after the last drug injection, in both brain and plasma. A challenge injection of fluoxetine (20 mg/kg, i.p.), however, was still able to increase the concentrations of steroids in both the brain and plasma of rats chronically treated with this drug. Acute foot-shock stress increased the cortical and plasma concentrations of steroids in rats chronically treated with fluoxetine to extents similar to those apparent in control rats. Conclusions: A repetitive increase in the brain concentrations of neuroactive steroids may contribute to the therapeutic action of fluoxetine.