Pregnenolone

The roots of Dictamnus dasycarpus

Neurosteroids are endogenous molecules that are enrichedin human brain. A number of neurosteroids demonstrate important pleiotropic actions that impact critical brainfunctions at physiologically relevant concentrations in rodent models. Pregnenolone (3β-hydroxypregn-5-en-20-one), also known as P5, is an endogenous steroid hormone.

In vitro: Pregnenolone is the precursor from which almost all of the other steroid hormones are made, including DHEA, testosterone, progesterone, the estrogens and cortisol. Pregnenolone also operates as a powerful neurosteroid in the brain, which modulates the transmission of messages from neuron to neuron and strongly influencing learning and memory processes [1].

In vivo: The ability of pregnenolone sulfate derivatives (PREGS) to modulate the age-induced learning impairment was tested in 16- month-old mice using the step-down type of passive avoidance. Decreased step-down latency was observed in the passive avoidance task in 16-month-old mice compared to 3-month-old mice, revealing retention deficits in old mice. Pretraining injections of PREGS dose-dependently improved the 24 h delay retention performances in this task in old mice [1].

Clinical trial: Human studies have reported improvement of learning and memory dysfunction after PREG administration to individuals with low PREGS levels, but other studies failed to detect significant cognitive effects of PREG administration [1].

Reference:
[1] Vallée M, Mayo W, Le Moal M.  Role of pregnenolone, dehydroepiandrosterone and their sulfate esters on learning and memory in cognitive aging. Brain Res Brain Res Rev. 2001 Nov;37(1-3):301-12.

Pregnenolone and dehydroepiandrosterone as precursors of native 7-hydroxylated metabolites which increase the immune response in mice.[Pubmed:8049138]

J Steroid Biochem Mol Biol. 1994 Jul;50(1-2):91-100.

Dehydroepiandrosterone (DHEA) and Pregnenolone (PREG) were both metabolized by homogenates of brain, spleen, thymus, perianal skin, ventral skin, intestine, colon, coecum and muscle tissues from mice. The use of 2H-labeled substrates and of the twin ion technique of gas chromatography-mass spectrometry permitted identification of 7 alpha-hydroxy-DHEA and of 5-androstene-3 beta, 17 beta-diol as DHEA metabolites in digests of all tissues. The extent of PREG metabolism was much lower than for DHEA with all tissues but amounts of the main transformation product were sufficient in brain, spleen and ventral skin digests for identification with 7 alpha-hydroxy-PREG. Dimethylsulfoxide (DMSO) solutions of DHEA, PREG and of their 7-hydroxylated metabolites were injected at different doses and time intervals prior to proximal subcutaneous administration of a lysozyme antigen. Quantities of anti-lysozyme IgG were measured in the serum of treated mice and compared with that from sham-treated animals. Increase of anti-lysozyme IgG was obtained with DHEA and PREG (1 g/kg) when injected 2 h prior to lysozyme. Much lower doses (160 times less) of 7 alpha-hydroxy-DHEA and -PREG were also found to be significantly active when administered at the moment of lysozyme injection. A larger dose of 7 beta-hydroxy-DHEA (50 mg/kg) was necessary for a similar effect. These results suggest that in tissues where immune response takes place, the locally-produced 7-hydroxy metabolites of PREG and DHEA are involved in a process which may participate in the physiological regulation of the body's immune response.

Pregnenolone treatment reduces severity of negative symptoms in recent-onset schizophrenia: an 8-week, double-blind, randomized add-on two-center trial.[Pubmed:24548129]

Psychiatry Clin Neurosci. 2014 Jun;68(6):432-40.

AIMS: Management of recent-onset schizophrenia (SZ) and schizoaffective disorder (SA) is challenging owing to frequent insufficient response to antipsychotic agents. This study aimed to test the efficacy and safety of the neurosteroid Pregnenolone in patients with recent-onset SZ/SA. METHODS: Sixty out- and inpatients who met DSM-IV criteria for SZ/SA, with suboptimal response to antipsychotics were recruited for an 8-week, double-blind, randomized, placebo-controlled, two-center add-on trial, that was conducted between 2008 and 2011. Participants were randomized to receive either Pregnenolone (50 mg/day) or placebo added on to antipsychotic medications. The primary outcome measures were the Positive and Negative Symptoms Scale and the Assessment of Negative Symptoms scores. Secondary outcomes included assessments of functioning, and side-effects. RESULTS: Analysis was by linear mixed model. Fifty-two participants (86.7%) completed the trial. Compared to placebo, adjunctive Pregnenolone significantly reduced Positive and Negative Symptoms Scale negative symptom scores with moderate effect sizes (d = 0.79). Significant improvement was observed in weeks 6 and 8 of Pregnenolone therapy among patients who were not treated with concomitant mood stabilizers (arms x visit x mood stabilizers; P = 0.010). Likewise, Pregnenolone significantly reduced Assessment of Negative Symptoms scores compared to placebo (d = 0.57), especially on blunted affect, avolition and anhedonia domain scores. Other symptoms, functioning, and side-effects were not significantly affected by adjunctive Pregnenolone. Antipsychotic agents, benzodiazepines and sex did not associate with Pregnenolone augmentation. Pregnenolone was well tolerated. CONCLUSIONS: Thus, add-on Pregnenolone reduces the severity of negative symptoms in recent-onset schizophrenia and schizoaffective disorder, especially among patients who are not treated with concomitant mood stabilizers. Further studies are warranted.

A role for picomolar concentrations of pregnenolone sulfate in synaptic activity-dependent Ca2+ signaling and CREB activation.[Pubmed:25057049]

Mol Pharmacol. 2014 Oct;86(4):390-8.

Fast excitatory synaptic transmission that is contingent upon N-methyl d-aspartate receptor (NMDAR) function contributes to core information flow in the central nervous system and to the plasticity of neural circuits that underlie cognition. Hypoactivity of excitatory NMDAR-mediated neurotransmission is hypothesized to underlie the pathophysiology of schizophrenia, including the associated cognitive deficits. The neurosteroid Pregnenolone (PREG) and its metabolites Pregnenolone sulfate (PregS) and allopregnanolone in serum are inversely associated with cognitive improvements after oral PREG therapy, raising the possibility that brain neurosteroid levels may be modulated therapeutically. PregS is derived from PREG, the precursor of all neurosteroids, via a single sulfation step and is present at low nanomolar concentrations in the central nervous system. PregS, but not PREG, augments long-term potentiation and cognitive performance in animal models of learning and memory. In this report, we communicate the first observation that PregS, but not PREG, is a potent (EC50 approximately 2 pM) enhancer of intracellular Ca(2+) that is contingent upon neuronal activity, NMDAR-mediated synaptic activity, and L-type Ca(2+) channel activity. Low picomolar PregS similarly activates cAMP response element-binding protein (CREB) phosphorylation (within 10 minutes), an essential memory molecule, via an extracellular-signal-regulated kinase/mitogen-activated protein kinase signal transduction pathway. Taken together, the results are consistent with a novel biologic role for the neurosteroid PregS that acts at picomolar concentrations to intensify the intracellular response to glutamatergic signaling at synaptic but not extrasynaptic, NMDARs by differentially augmenting CREB activation. This provides a genomic signal transduction mechanism by which PregS could participate in memory consolidation of relevance to cognitive function.

Pregnenolone stimulates LNCaP prostate cancer cell growth via the mutated androgen receptor.[Pubmed:11179903]

J Steroid Biochem Mol Biol. 2000 Dec 1;75(1):1-10.

Pregnenolone (P(5)), a common precursor of many steroids, is present in the blood of normal adult men at concentrations of 1-3 nM. In vitro, P(5) was found to stimulate LNCaP-cell proliferation 7-8-fold at a physiological concentration (2 nM), and 3-4-fold at a subphysiological concentration (0.2 nM). Growth stimulation at the 2-nM concentration was comparable with that of the androgen, dihydrotestosterone at its physiological concentration (0.5 nM; 9-10-fold increase in cell number). To determine whether P(5) or its metabolites were mediating this growth response, LNCaP cells were incubated with [3H]P(5) and high-performance liquid chromatography (HPLC) was performed. After a 48-h exposure, two unidentified metabolites were detected. Although, the P(5) metabolites slightly increased LNCaP-cell growth in vitro, their effect was significantly less than P(5) alone, suggesting that the growth stimulation was mediated by P(5) itself. We further showed that P(5) sustained its proliferative activity in vivo and stimulated the growth of LNCaP-tumor xenografts in intact male SCID mice as well as in castrated animals. In order to determine whether P(5) was binding to a specific site in LNCaP cells, receptor binding studies were performed. Scatchard analysis predicted for a single class of binding sites with K(d)=1.4 nM. Studies were performed to determine the effects of P(5) on transcription mediated by wild-type and LNCaP androgen receptors. P(5) was shown to activate transcription through the LNCaP androgen receptor (AR), but not the wild-type AR. This implies that P(5) most likely stimulates LNCaP-cell proliferation through binding to the cellular mutated AR present in LNCaP cells. We have also demonstrated that drugs designed to be antagonists of the androgen, progesterone and estrogen receptors, and one of our novel compounds designed to be an inhibitor of androgen synthesis, were potent inhibitors of the AR-mediated transcriptional activity induced by P(5), and were able to inhibit LNCaP-cell proliferation. These findings suggest that some prostate cancer patients who appear to become hormone-independent may have tumors which are stimulated by P(5) via a mutated AR and that these patients could benefit from treatment with antiestrogens, antiprogestins, or with some of our novel androgen synthesis inhibitors.

Pregnenolone (3β-Hydroxy-5-pregnen-20-one) is a powerful neurosteroid, the main precursor of various steroid hormones including steroid ketones. Pregnenolone acts as a signaling-specific inhibitor of cannabinoid CB1 receptor, inhibits the effects of tetrahydrocannabinol (THC) that are mediated by the CB1 receptors. Pregnenolone can protect the brain from cannabis intoxication.

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