Differential hypothalamic-pituitary-adrenal activation of the neuroactive steroids pregnenolone sulfate and deoxycorticosterone in healthy controls and alcohol-dependent subjects

Abstract

Ethanol and the neuroactive steroids have interactive neuropharmacological effects and chronic ethanol administration blunts the ethanol-induced increase in neuroactive steroid levels in rodent plasma and brain. Few studies have explored neuroactive steroid regulation in alcohol-dependent human subjects. In fact, the regulation of adrenal neuroactive steroids has not been well defined in healthy controls. We thus explored the regulation of two neuroactive steroids, pregnenolone sulfate (PREG-S) and deoxycorticosterone, by pharmacological challenges to the hypothalamic-pituitary-adrenal (HPA) axis in healthy controls and 1-month abstinent alcohol-dependent patients with co-occurring nicotine dependence. Plasma levels of PREG-S and deoxycorticosterone were measured by radioimmunoassay in controls and alcohol-dependent patients after challenges of naloxone, ovine corticotrophin releasing hormone (oCRH), dexamethasone, cosyntropin, and cosyntropin following high-dose dexamethasone. In addition, basal diurnal measures of both hormones were obtained. PREG-S plasma levels in healthy controls were increased by cosyntropin challenge (with and without dexamethasone pretreatment) and decreased by dexamethasone challenge. However, PREG-S concentrations were not altered by naloxone or oCRH challenges, suggesting that PREG-S is not solely regulated by hypothalamic or pituitary stimulation. Deoxycorticosterone, in contrast, is regulated by HPA challenge stimulation in a manner similar to cortisol. Alcohol-dependent patients had a blunted PREG-S response to cosyntropin (with and without dexamethasone pretreatment). Furthermore, the time to peak deoxycorticosterone response following oCRH was delayed in alcohol-dependent patients compared to controls. These results indicate that plasma PREG-S and deoxycorticosterone levels are differentially regulated by HPA axis modulation in human plasma. Further, alcohol-dependent patients show a blunted PREG-S response to adrenal stimulation and a delayed deoxycorticosterone response to oCRH challenge.

Figure 1

Schematic representation of the neuroactive steroids biosynthetic pathway from human adrenal glands.

Figure 2

Diurnal baseline plasma PREG-S (A) and deoxycorticosterone (B) levels in control subjects (n=10) and alcohol-dependent patients (n=11). Data (mean ± SEM) are expressed as ng/ml. Asterisks indicate significant difference between the time points: *p<0.05 and **p<0.001 (two-way ANOVA).

Figure 3

Time course of plasma PREG-S (A) and deoxycorticosterone (B) levels in control subjects (n=10) and alcohol-dependent patients (n=10) after administration of naloxone (125 µg/kg, IV) at 2000h. Data (mean ± SEM) are expressed as ng/ml. Letters indicate significant difference from basal measures: ^ap<0.05, ^bp<0.01 and ^cp<0.001 vs. −20 min for control subjects; ^dp<0.01 and ^ep<0.001 vs. −20 min for alcohol-dependent patients (two-way repeated measures ANOVA).

Figure 4

Time course of plasma PREG-S (A) and deoxycorticosterone (B) levels in control subjects (n=10) and alcohol-dependent patients (n=11) after administration of oCRH (0.4 µg/kg, IV) at 2000h. Data (mean ± SEM) are expressed as ng/ml. Asterisk indicates significant difference between controls and alcohol-dependent patients: *p<0.001; letters indicate significant difference from basal measures: ^ap<0.001 vs. −45 min for control subjects; ^bp<0.05 and ^cp<0.001 vs. −45 min for alcohol-dependent patients (two-way ANOVA). (C) Data (mean ± SEM) represent the mean time interval (minutes) necessary to reach the deoxycorticosterone peak response after administration of oCRH in control subjects and alcohol-dependent patients (*p=0.0023, paired t test).

Figure 5

Effect of cosyntropin on plasma PREG-S (A) and deoxycorticosterone (B) levels incontrol subjects (n=10) and alcohol-dependent patients (n=11). Cosyntropin (0.01 µg/kg, IV) was administered at 0800h. Data (mean ± SEM) are expressed as ng/ml. Asterisks indicate significant differences between basal and cosyntropin groups: *p<0.01 and**p<0.001 vs. the respective basal group (two-way repeated measures ANOVA).

Figure 6

Time course of plasma PREG-S (A) and deoxycorticosterone (C) levels in control subjects (n=10) and alcohol-dependent patients (n=11) after administration of dexamethasone plus cosyntropin. Dexamethasone (8 mg, IV) was administered at 2300h; cosyntropin (0.01 µg/kg, IV) was administered at 0800h the following day. Data (mean ± SEM) are expressed as ng/ml. Letters indicate significant difference from basal measures: ^ap<0.05 and ^bp<0.01 for control subjects; ^cp<0.01 and ^dp<0.001 for alcohol-dependent patients; ^ep<0.001 for both groups (two-way ANOVA). Section B shows the PREG-S area under the curve (AUC) for controls and alcohol-dependent patients following dexamethasone plus cosyntropin administration. Asterisk indicates significant difference between controls and alcohol-dependent patients: *p=0.037 (Unpaired t test).

Figure 7

Effect of dexamethasone on plasma PREG-S (A) and deoxycorticosterone (B) levels incontrol subjects (n=10) and alcohol-dependent patients (n=11). Dexamethasone (8 mg, IV) was administered at 2300h and PREG-S and deoxycorticosterone levels were measured nine hours later. Basal levels were obtained from a 0715h sample. Data (mean ± SEM) are expressed as ng/ml. Asterisks indicate significant differences between basal and dexamethasone groups: *p<0.001 vs. the respective basal group (two-way repeated measures ANOVA).