Pregnanolone

Comparison of dehydroepiandrosterone (DHEA) and pregnanolone with existing pharmacotherapies for alcohol abuse on ethanol- and food-maintained responding in male rats.[Pubmed:25620274]

Alcohol. 2015 Mar;49(2):127-38.

The present study compared two putative pharmacotherapies for alcohol abuse and dependence, dehydroepiandrosterone (DHEA) and Pregnanolone, with two Food and Drug Administration (FDA)-approved pharmacotherapies, naltrexone and acamprosate. Experiment 1 assessed the effects of different doses of DHEA, Pregnanolone, naltrexone, and acamprosate on both ethanol- and food-maintained responding under a multiple fixed-ratio (FR)-10 FR-20 schedule, respectively. Experiment 2 assessed the effects of different mean intervals of food presentation on responding for ethanol under a FR-10 variable-interval (VI) schedule, whereas Experiment 3 assessed the effects of a single dose of each drug under a FR-10 VI-80 schedule. In Experiment 1, all four drugs dose-dependently decreased response rate for both food and ethanol, although differences in the rate-decreasing effects were apparent among the drugs. DHEA and Pregnanolone decreased ethanol-maintained responding more potently than food-maintained responding, whereas the reverse was true for naltrexone. Acamprosate decreased responding for both reinforcers with equal potency. In Experiment 2, different mean intervals of food presentation significantly affected the number of food reinforcers obtained per session; however, changes in the number of food reinforcements did not significantly affect responding for ethanol. Under the FR-10 VI-80 schedule in Experiment 3, only naltrexone significantly decreased both the dose of alcohol presented and blood ethanol concentration (BEC). Acamprosate and Pregnanolone had no significant effects on any of the dependent measures, whereas DHEA significantly decreased BEC, but did not significantly decrease response rate or the dose presented. In summary, DHEA and Pregnanolone decreased ethanol-maintained responding more potently than food-maintained responding under a multiple FR-10 FR-20 schedule, and were more selective for decreasing ethanol self-administration than either naltrexone or acamprosate under that schedule. Experiment 2 showed that ethanol intake was relatively independent of the interval of reinforcement in the food-maintained component, and Experiment 3 showed that naltrexone was the most effective drug at the doses tested when the interval for food reinforcement was low and maintained under a variable-interval schedule.

LC-MS/MS simultaneous analysis of allopregnanolone, epiallopregnanolone, pregnanolone, dehydroepiandrosterone and dehydroepiandrosterone 3-sulfate in human plasma.[Pubmed:28207286]

Bioanalysis. 2017 Mar;9(6):527-539.

AIM: Several neuropsychopharmacological properties have been attributed to the 3alpha-reduced pregnane steroids, alloPregnanolone and Pregnanolone, as well as to dehydroepiandrosterone sulfate because of their ability to modulate gamma-aminobutyric acid (GABAA) receptors in the CNS. In order to understand better their role in several mechanisms in CNS, a new methodology is proposed to monitor these compounds in human plasma. Methodology & results: The analytes were first derivatized with 2-hydrazinopyridine and extracted from plasma using SPE. Then, the compounds were separated and detected by LC-MS/MS. A mobile phase of formic acid (0.1%) in water and methanol through a gradient of composition and a flow rate of 0.3 ml min(-1) resulted in good separations of the analytes. Linear responses in wide range of concentrations and LOQs ranging from 10 (dehydroepiandrosterone 3-sulfate) to 40 pg ml(-1) (dehydroepiandrosterone) were obtained in <9 min. The method proposed has been validated and then applied to monitor these neurosteroids in plasma samples from ten volunteers. CONCLUSION: For the first time, a straightforward and reliable method for the chromatographic separation of alloPregnanolone, epialloPregnanolone and Pregnanolone, as well as of dehydroepiandrosterone and dehydroepiandrosterone 3-sulfate was carried out, with optimal accuracy, sensitivity and specificity.

Using drug combinations to assess potential contributions of non-GABAA receptors in the discriminative stimulus effects of the neuroactive steroid pregnanolone in rats.[Pubmed:25072672]

Physiol Behav. 2014 Oct;137:33-41.

Neuroactive steroids are increasingly implicated in the development of depression and anxiety and have been suggested as possible treatments for these disorders. While neuroactive steroids, such as Pregnanolone, act primarily at gamma-aminobutyric acidA (GABAA) receptors, other mechanisms might contribute to their behavioral effects and could increase their clinical effectiveness, as compared with drugs acting exclusively at GABAA receptors (e.g., benzodiazepines). The current study examined the role of non-GABAA receptors, including N-methyl-d-aspartate (NMDA) and serotonin3 (5-HT3) receptors, in the discriminative stimulus effects of Pregnanolone. Separate groups of rats discriminated either 3.2mg/kg Pregnanolone from vehicle or 0.32mg/kg of the benzodiazepine midazolam from vehicle while responding under a fixed-ratio 10 schedule for food pellets. When administered alone in both groups, Pregnanolone and midazolam produced >/=80% drug-lever responding, the NMDA receptor antagonists dizocilpine and phencyclidine produced >/=60 and >/=30% drug-lever responding, respectively, and the 5-HT3 receptor agonist 1-(m-chlorophenyl)-biguanide (CPBG) and morphine produced <20% drug-lever responding up to doses that markedly decreased response rates. When studied together, neither dizocilpine, phencyclidine, CPBG nor morphine significantly altered the midazolam dose-effect curve in either group. Given that CPBG is without effect, it is unlikely that 5-HT3 receptors contribute substantially to the discriminative stimulus effects of Pregnanolone. Similarities across groups in effects of dizocilpine and phencyclidine suggest that NMDA receptors do not differentially contribute to the effects of Pregnanolone. Thus, NMDA and 5-HT3 receptors are not involved in the discriminative stimulus effects of Pregnanolone.

Increased Motor-Impairing Effects of the Neuroactive Steroid Pregnanolone in Mice with Targeted Inactivation of the GABAA Receptor gamma2 Subunit in the Cerebellum.[Pubmed:27833556]

Front Pharmacol. 2016 Oct 27;7:403.

Endogenous neurosteroids and neuroactive steroids have potent and widespread actions on the brain via inhibitory GABAA receptors. In recombinant receptors and genetic mouse models their actions depend on the alpha, beta, and delta subunits of the receptor, especially on those that form extrasynaptic GABAA receptors responsible for non-synaptic (tonic) inhibition, but they also act on synaptically enriched gamma2 subunit-containing receptors and even on alphabeta binary receptors. Here we tested whether behavioral sensitivity to the neuroactive steroid agonist 5beta-pregnan-3alpha-ol-20-one is altered in genetically engineered mouse models that have deficient GABAA receptor-mediated synaptic inhibition in selected neuronal populations. Mouse lines with the GABAA receptor gamma2 subunit gene selectively deleted either in parvalbumin-containing cells (including cerebellar Purkinje cells), cerebellar granule cells, or just in cerebellar Purkinje cells were trained on the accelerated rotating rod and then tested for motor impairment after cumulative intraperitoneal dosing of 5beta-pregnan-3alpha-ol-20-one. Motor-impairing effects of 5beta-pregnan-3alpha-ol-20-one were strongly increased in all three mouse models in which gamma2 subunit-dependent synaptic GABAA responses in cerebellar neurons were genetically abolished. Furthermore, rescue of postsynaptic GABAA receptors in Purkinje cells normalized the effect of the steroid. Anxiolytic/explorative effects of the steroid in elevated plus maze and light:dark exploration tests in mice with Purkinje cell gamma2 subunit inactivation were similar to those in control mice. The results suggest that, when the deletion of gamma2 subunit has removed synaptic GABAA receptors from the specific cerebellar neuronal populations, the effects of neuroactive steroids solely on extrasynaptic alphabeta or alphabetadelta receptors lead to enhanced changes in the cerebellum-generated behavior.

Differential modulation of the gamma-aminobutyric acid type C receptor by neuroactive steroids.[Pubmed:10496958]

Mol Pharmacol. 1999 Oct;56(4):752-9.

Gamma-aminobutyric acid type C receptor channels (GABA(C)Rs) composed of rho subunits are pharmacologically distinct from GABA(A) receptor channels (GABA(A)Rs). This difference is illustrated by the insensitivity of homo-oligomeric rho(1) receptor channels to many known modulators of GABA(A)Rs, such as barbiturates and benzodiazepines. A number of endogenous metabolites of corticosterone and progesterone, known as neuroactive steroids, compose yet another class of compounds that can modulate GABA(A)Rs. Here, several neuroactive steroids are shown to also modulate the rho(1) receptor channel. 5alpha-Pregnane-3alpha,21-diol-20-one (allotetrahydrodeoxycorticosterone), 5alpha-pregnane-3alpha-ol-11, 20-dione (alphaxalone), and 5alpha-pregnane-3alpha-ol-20-one (alloPregnanolone) potentiated the GABA-evoked currents from rho(1) receptor channels and concomitantly altered the deactivation kinetics by prolonging the decay time. In contrast, 5beta-pregnane-3alpha-ol-20-one (Pregnanolone), 5beta-pregnane-3, 20-dione (5beta-dihydroprogesterone), and 5beta-pregnane-3alpha, 21-diol-20-one (tetrahydrodeoxycorticosterone), all potentiators of GABA(A)Rs, inhibited the GABA-elicited currents of the rho(1) receptor channel. In comparison to GABA(A)Rs, the modulation of rho(1) receptor channels by these neuroactive compounds occurred with relatively high concentrations of the neuroactive steroids and was more prominent in the presence of low concentrations of GABA, equivalent to fractions of the EC(50) value of the rho(1) receptor channel. Structural comparison of these six neuroactive steroids reveals that the key parameter in determining the mode of modulation for the rho(1) receptor channel is the position of the hydrogen atom bound to the fifth carbon, imposing a trans- or cis-configuration in the backbone structure. This is the first demonstration of isomeric compounds that can differentially modulate the activity of the rho(1) receptor channel.

Structure-activity relationships for steroid interaction with the gamma-aminobutyric acidA receptor complex.[Pubmed:3033209]

J Pharmacol Exp Ther. 1987 Apr;241(1):346-53.

Certain steroids are potent barbiturate-like modulators of the gamma-aminobutyric acidA (GABA) receptor-chloride ionophore complex in rat brain membranes. At nanomolar to low micromolar concentrations, these steroids stimulate [3H]flunitrazepam and [3H] muscimol binding and displace the convulsant [35S]t-butylbicyclophosphorothionate from its binding site in an allosteric manner, in addition to enhancing Cl- conductance responses to GABA recorded in cultured rat hippocampal and spinal neurons. A stringent structure-activity relationship exists for these interactions of steroids with the GABAA receptor complex. Comparison of the structure-activity relationship data obtained in this study with those for steroid-induced general anesthesia strongly suggests that steroidal anesthesia may result from the interaction between steroids and the GABAA receptor. The essential features of the active structures are a 5 alpha or 5 beta-reduced pregnane skeleton with a hydroxyl at C3 in the alpha-position and a ketone group at C20. These features are all present in some naturally occurring steroids, including metabolites of deoxycorticosterone and progesterone, that show potent activity at the GABAA receptor complex. Two of the compounds investigated are known to be formed in vivo as reduced metabolites of endogenous steroid hormones: 5 alpha-pregnane-3 alpha -ol-20-one and 5 alpha-pregnane-3 alpha,21-diol-20-one, which are derived from progesterone and deoxycorticosterone, respectively. These two steroids produce a striking prolongation of GABA-mediated inhibitory postsynaptic currents recorded at synapses between rat hippocampal neurons in culture and could conceivably regulate GABA-mediated inhibition under some physiologic and pathologic conditions.