Sex Differences in Salivary Cortisol Levels Following Naltrexone Administration

Blunted opioid regulation of the HPA stress response during nicotine withdrawal: therapeutic implications

Endogenous opioids regulate pain, drug reward, and stress responses. We have previously shown reduced hypothalamic-pituitary-adrenal (HPA) responses to psychological stress and to opioid blockade among dependent smokers. In this study, we examined the extent to which biologically confirmed nicotine withdrawal alters endogenous opioid regulation of HPA axis functioning during rest and in response to acute stress. Smokers were randomly assigned to one of two conditions; 24 h withdrawal from all nicotine-containing products (n = 62) or smoking ad libitum (n = 44). A nonsmoking comparison group (n = 43) was also included. Participants (85 males and 64 females) completed two acute stress sessions during which a placebo or 50 mg of naltrexone (opioid antagonist) were administered using a double-blind design. Blood and saliva samples (assayed for cortisol and adrenocorticotropic hormone, i.e. ACTH) and mood measures were obtained during a resting absorption period, after acute stress (public speaking, mental arithmetic, and cold pressor tasks), and during an extended recovery period. Results indicated that opioid blockade (naltrexone) was associated with increased ACTH and cortisol responses to stress, and tobacco withdrawal was associated with blunted hormonal responses. A pattern of sex differences also emerged, with women exhibiting reduced ACTH responses to stress and higher ACTH and plasma cortisol responses to opioid blockade. These results indicated that compared to ad libitum smoking, nicotine withdrawal is associated with blunted opioid modulation of the HPA axis. Sex may modulate these effects. Blunted endogenous opioid regulation may underlie an incentive process that reinforces smoking behavior and may warrant therapeutic attention.

Early life adversity diminishes the cortisol response to opioid blockade in women: Studies from the Family Health Patterns project

Early life adversity (ELA) contributes to behavioral impulsivity along with risk for substance use disorders, both accompanied by blunted stress-axis reactivity. However, the biological contributors to blunted stress reactivity are not known. We took advantage of the fact that women have significant opioid inhibition of cortisol output by using the opioid antagonist, naltrexone, to unmask opioid interactions due to ELA. We administered 50 mg of naltrexone or placebo to 72 healthy women (23 years of age) in a double-blind crossover study and observed deviations in cortisol secretion from placebo over the next 180 minutes. ELA was assessed by reported exposure to physical and sexual abuse or neglect and low socioeconomic status and scored as Low, Medium, or High (0, 1-2, and 3+). The ELA groups all had identical placebo-day cortisol secretion, indicating normal basal regulation of the hypothalamic-pituitary-adrenocortical axis. Cortisol rises to naltrexone were largest in the Low-ELA group and strongly blunted in the High-ELA group (F = 3.51, p = 0.035), indicating a lack of opioid function in women with high degrees of ELA. The Low-ELA women reported dysphoric responses to naltrexone (F = 4.05, p = .022) indicating a mild opioid withdrawal, an effect that was absent in the High-ELA group. Women exposed to ELA have blunted cortisol responses to naltrexone, indicating reduced opioid regulation of the stress axis. Central opioid changes may be one pathway linking ELA to blunted stress reactivity in adulthood.

Sex differences in acute hormonal and subjective response to naltrexone: The impact of menstrual cycle phase

Women often exhibit larger hormonal and subjective responses to opioid receptor antagonists than men, but the biological mechanisms mediating this effect remain unclear. Among women, fluctuations in estradiol (E2) and progesterone (P4) across the menstrual cycle (MC) affect the endogenous opioid system. Therefore, the goal of the current study was to compare acute naltrexone response between women in the early follicular phase of the MC (low E2 and P4), women in the luteal phase of the MC (high E2 and P4), and men. Seventy healthy controls (n=46 women) participated in two morning sessions in which they received 50mg naltrexone or placebo in a randomized, counterbalanced order. Women were randomized to complete both sessions in either the early follicular (n=23) or luteal phase of the MC. Serum cortisol, salivary cortisol, prolactin, luteinizing hormone (LH), and subjective response were assessed upon arrival to the laboratory and at regular intervals after pill administration. In luteal and early follicular women but not men, naltrexone (vs. placebo) increased serum cortisol and prolactin levels from baseline; however, the naltrexone-induced increases in these hormones were significantly greater in luteal women than early follicular women. Additionally, only luteal women demonstrated an increase from baseline in salivary cortisol levels and the severity of adverse drug effects in response to naltrexone. In sum, the results indicate that luteal phase women are more sensitive to acute hormonal and subjective effects of naltrexone than early follicular women and men. These findings may have important implications for the use of naltrexone in women.

Naltrexone effects on cortisol secretion in women and men in relation to a family history of alcoholism: studies from the Oklahoma Family Health Patterns Project

Naltrexone evokes a cortisol response through its blockade of central opioid receptors on the hypothalamic-pituitary-adrenocortical axis (HPA). The magnitude of this cortisol response may be useful as a probe for central opioid activity in different groups of subjects. Accordingly, the present study examined the effect of opioid blockade on the HPA in 70 women and 58 men with (N=41) and without (N=87) a family history of alcoholism, using a randomized, placebo-controlled, double blind administration of oral naltrexone (50mg). Saliva cortisol was sampled at baseline prior to placebo or naltrexone and again every 30 min over the next 180 min. Women had significantly larger cortisol responses to naltrexone than did the men, F=6.88, p<0.0001. There were no significant differences in cortisol response between groups differing in family history of alcoholism, F=0.65, p>0.69. The present results confirm that women have much greater central opioid restraint on the HPA than men do and that this endogenous restraint is unmasked by opioid blockade. However the results provide no evidence of a differential central opioid tonus in persons with a family history of alcoholism at this dose of naltrexone. The cortisol response to naltrexone may be a useful probe for central opioid activity in women and to a lesser degree in men.

Gender differences in alcohol treatment: an analysis of outcome from the COMBINE study

BACKGROUND

Relatively few studies have examined gender differences in the effectiveness of specific behavioral or pharmacologic treatment of alcohol dependence. The aim of this study is to assess whether there were gender differences in treatment outcomes for specific behavioral and medication treatments singly or in combination by conducting a secondary analysis of public access data from the national, multisite NIAAA-sponsored COMBINE study.

METHODS

The COMBINE study investigated alcohol treatment among 8 groups of patients (378 women, 848 men) who received medical management (MM) with 16 weeks of placebo, naltrexone (100 mg/day), acamprosate (3 g/day), or their combination with or without a specialist-delivered combined behavioral intervention. We examined efficacy measures separately for men and women, followed by an overall analysis that included gender and its interaction with treatment condition in the analyses. These analyses were performed to confirm whether the findings reported in the parent trial were also relevant to women, and to more closely examine secondary outcome variables that were not analyzed previously for gender effects.

RESULTS

Compared to men, women reported a later age of onset of alcohol dependence by approximately 3 years, were significantly less likely to have had previous alcohol treatment, and drank fewer drinks per drinking day. Otherwise, there were no baseline gender differences in drinking measures. Outcome analyses of 2 primary (percent days abstinent and time to first heavy drinking day) and 2 secondary (good clinical response and percent heavy drinking days) drinking measures yielded the same overall pattern in each gender as that observed in the parent COMBINE study report. That is, only the naltrexone by behavioral intervention interaction reached or approached significance in women as well as in men. There was a naltrexone main effect that was significant in both men and women in reduction in alcohol craving scores with naltrexone-treated subjects reporting lower craving than placebo-treated subjects.

CONCLUSIONS

This gender-focused analysis found that alcohol-dependent women responded to naltrexone with COMBINE's Medical Management, similar to the alcohol-dependent men, on a wide range of outcome measures. These results suggest that clinicians can feel comfortable prescribing naltrexone for alcohol dependence in both men and women. In this study, it is also notable that fewer women than men reported receiving any alcohol treatment prior to entry into the COMBINE study. Of note, women tend to go to primary health care more frequently than to specialty substance abuse programs for treatment, and so the benefit we confirm for women of the naltrexone and MM combination has practical implications for treating alcohol-dependent women.

Acute HPA axis response to naltrexone differs in female vs. male smokers

BACKGROUND

Both opioid antagonist administration and cigarette smoking acutely increase hypothalamic-pituitary-adrenal (HPA) axis activity as measured by adrenocorticotropic hormone (ACTH) and cortisol levels. However, male and female smokers may differ in their response to the opioid antagonist naltrexone, which may be partially mediated by sex differences in HPA axis function. Smokers, as a group, have frequently been shown to have HPA axis dysfunction, which may have relevance to the course and maintenance of nicotine dependence. The purpose of this study was to examine possible sex differences in HPA axis function by comparing stress-hormone response to naltrexone within healthy male and female smokers. Additionally, exploratory analyses compared the combined effects of naltrexone and cigarette smoking on hormonal responsivity between the sexes.

METHOD

Thirty-eight healthy smokers (22 men) were tested in two separate morning sessions after 12h of smoking abstinence. For women, self-reports of menstrual cycle information were obtained prior to each session (date of last menstruation, cycle length, reproductive phase, etc.). Each participant received 50mg naltrexone or placebo capsule (in random order) and plasma levels of ACTH and cortisol were assessed at regular intervals for several hours. A subgroup of 12 participants underwent a similar, additional session in which they smoked a single cigarette three hours after naltrexone administration.

RESULTS

Naltrexone significantly increased ACTH and cortisol levels in women, but not men (DrugxSexxTime, p<0.05). A post hoc analysis suggested that women at an estimated 'high estrogen' phase had a greater cortisol response (DrugxEstrogen level, p<0.05) than those at an estimated 'low estrogen' phase. Exploratory analyses showed that smoking a single cigarette potentiated naltrexone-induced increases in ACTH (p<0.05) and cortisol (p<0.01) in all participants.

CONCLUSION

The findings support the hypothesis that women are more sensitive to opioid antagonism at the level of the HPA axis. Although further studies are needed to examine mechanisms underlying these responses, both results may have clinical implications for the use of naltrexone as a treatment for nicotine dependence.

Can non-invasive glucocorticoid measures be used as reliable indicators of stress in animals?

Refinement techniques are being increasingly employed in all fields of animal research to try to ensure that the highest standards of welfare are upheld. This review concerns one of the main emerging techniques for the assessment of welfare itself, namely the non-invasive measurement of glucocorticoids (GCs) as indicators of stress. The paper is divided into three sections. The first discusses the relationship between GCs and stress. The second section considers whether factors other than stress are linked to rises in GCs, eg exercise, oestrus cycle and diet. The final part examines the reliability of the non-invasive techniques that measure GCs from samples of saliva and faeces. Although it is important to take into account some caveats associated with the methodologies employed, it is concluded, nevertheless, that these techniques can give accurate and reliable information regarding the welfare status of an individual or group of animals without the procedures themselves causing any kind of distress to the subjects.