Hypercortisolemia is experienced during both chronic alcohol ingestion (Adinoff et al., 2003; Mendelson and Stein, 1966; Stokes, 1973) and repeated bouts of alcohol withdrawal (Adinoff et al., 1991; Iranmanesh et al., 1989; Keedwell et al., 2001). The prolonged state of glucocorticoid excess in heavy, daily drinkers (Adinoff et al., 2003; Mendelson and Stein, 1966) seems to induce pituitary and adrenocortical hyporesponsiveness that persists after cessation of drinking. Pharmacologic interventions that restore equilibrium to the hypothalamic-pituitary-adrenal (HPA) axis may have potential in the treatment of alcohol dependence. Therefore, isolating the specific level of axis disruption, the degree of physiological hyposensitivity at each organ level, and the persistence of these alterations upon abstinence assumes increasing importance. Such an understanding would allow a targeted, dose-appropriate pharmacologic intervention upon the critical axis disruption during a temporally relevant period of biological vulnerability. The HPA cascade begins with central activation of hypothalamic corticotropin-releasing hormone (CRH), primarily in response to fearful or anxiety-inducing stressors. CRH then induces the synthesis and secretion of corticotropin from the anterior pituitary gland, which in turn stimulates the production of glucocorticoids from the adrenal cortex. The glucocorticoids (primarily cortisol in humans) have a negative feedback effect on both hypothalamic CRH and pituitary corticotropin secretion. As noted, the HPA axis exhibits diminished responsiveness during early abstinence. For example, cerebrospinal fluid measures of CRH are reduced in abstinent alcohol-dependent individuals (Geracioti et al., 1994), suggesting a decrease in CRH hypothalamic release. In response to naloxone, which blocks opioid tonic inhibition of CRH secretion, Inder et al. (1995) observed a blunted corticotropin response in alcohol-dependent men who were 10 days to 6 weeks abstinent. This report suggested a down-regulation of hypothalamic CRH and/or pituitary corticotroph receptors. A number of investigators (Adinoff et al., 1990; Bardeleben et al., 1989; Costa et al., 1996; Ehrenreich et al., 1997; Loosen et al., 1991) have reported a similar blunting of the corticotropin response to ovine corticotropin-releasing hormone (oCRH), which directly stimulates pituitary corticotrophs. Adinoff et al. (1990) demonstrated that the corticotropin suppression seems to gradually resolve after 3 weeks of abstinence, although others have shown that this response persists for at least 12 weeks of abstinence (Ehrenreich et al., 1997). The pituitary corticotropin response has also been shown to be suppressed after nicotine (Coiro and Vescovi, 1999), hyperthermia (Vescovi et al., 1997), and insulin-induced hypoglycemia (Costa et al., 1996). Downstream adrenocortical secretion is suppressed after an alcohol challenge (Merry and Marks, 1972), insulin-induced hypoglycemia (Costa et al., 1996), operative trauma (Margraf et al., 1967), nicotine (Coiro and Vescovi, 1999), CRH stimulation (Bailly et al., 1989), cosyntropin stimulation (Wand and Dobs, 1991), hyperthermia (Vescovi et al., 1997), cold pressor (Errico et al., 1993), mental arithmetic (Errico et al., 1993), and public speaking (Lovallo et al., 2000) (for review, see Adinoff et al., 1998). These cumulative studies implicate a similarly muted response at each level of the HPA axis for several days, if not weeks, after cessation of drinking in alcohol-dependent individuals. The relative consistency of this literature, however, does not define the relative contribution of each axis component. Previous studies, for example, have typically used only a single provocative measure of HPA axis reactivity, limiting concurrent assessments of the hierarchical levels of HPA axis functioning. Hypothalamic, pituitary, and adrenal sensitivity to both exogenous and endogenous stimulation also remains uncertain because high doses of biological stimuli have typically been used to assess the system. Such severe activation may produce a ceiling response, particularly of the adrenocortical response, thus masking more subtle disruptions. In addition, the resolution or persistence of axis disruption with more extended periods of abstinence remains uncertain. Most studies have assessed HPA axis functioning in a patient cohort exhibiting varied abstinence intervals, leaving the time frame of HPA persistence or recovery unanswered. Finally, many studies of HPA axis responsiveness include patients with psychiatric and/or other substance use disorders. Because disruptions in HPA axis alterations have been documented in other substance use disorders (for review, see Kreek and Koob, 1998; Sinha, 2001) and psychiatric disorders (Gold and Chrousos, 2002; Yehuda, 2001), it is critical to separate out the pathophysiology induced by chronic alcohol ingestion as opposed to concomitant disease processes. In a series of studies, we assessed hypothalamic, pituitary, and adrenal responsiveness in 1-month alcohol-dependent men. Because of restrictions on the volume of blood withdrawal and the importance of obtaining all studies during a similar period of abstinence, two distinct groups of alcohol-dependent participants were compared with healthy control participants. In part 1 of the study (Adinoff et al., 2005), corticotropin and cortisol pulsatile characteristics were obtained from 2000 to 0800 hr, adrenocortical sensitivity was assessed in both the presence and the relative absence of endogenous pituitary corticotropin, and the pituitary corticotropin response to dexamethasone inhibition was obtained. In the current study (part 2), hypothalamic, pituitary, and adrenal activation was assessed with low doses of both oCRH and naloxone. In addition, corticotropin and cortisol pulsatility were determined from 0800 to 2000 hr. We hypothesized (1) that the net integrated corticotropin and cortisol responses to oCRH stimulation would be suppressed in the alcohol-dependent group compared with the healthy controls, indicating decreased pituitary responsiveness and (2) that the net integrated corticotropin and cortisol responses to naloxone stimulation would also be suppressed in the alcohol-dependent population compared with healthy controls, reflecting altered endogenous opioid activity at the hypothalamic level.