Noradrenergic function and clinical outcome in antidepressant pharmacotherapy.

Controversy remains regarding the role of noradrenergic systems in determining clinical response to antidepressant pharmacotherapy. Pineal gland production of melatonin can serve as a physiologic index of noradrenergic function. The aim of this study was to examine the effects of antidepressant treatment on 24-hour urinary excretion of the principle metabolite of melatonin, 6-sulfatoxymelatonin in treatment responders and nonresponders. Twenty-four outpatients meeting DSM-III-R criteria for Major Depression received treatment with either fluvoxamine or imipramine for 6 weeks while participating in a placebo-controlled double-blind clinical trial. Twenty-four hour excretion of 6-sulfatoxymelatonin was measured at baseline and at the conclusion of the treatment trial. Changes in urinary excretion of 6-sulfatoxymelatonin distinguished antidepressant responders from nonresponders, with a significant increase observed in the former group and a significant decrease in the latter. The degree of clinical response was correlated with the change in 6-sulfatoxymelatonin excretion. These results suggest that enhanced noradrenergic function may play an important role in determining clinical response to antidepressant pharmacotherapy.

Combination pharmacotherapy: a mixture of small doses of naltrexone, fluoxetine, and a thyrotropin-releasing hormone analogue reduces alcohol intake in three strains of alcohol-preferring rats.

It is common to treat some diseases with more than one medication simultaneously. Since more than one neurotransmitter system is involved in alcohol-seeking behaviour, then a therapeutic approach that targets more than one system should be more effective in reducing alcohol intake than one addressing a single system. To test this hypothesis, we compared the efficacy of low doses of individual drugs reported to reduce voluntary alcohol drinking to the efficacy of a mixture of these agents at the same low doses in reducing alcohol intake in three strains of alcohol-preferring rats (P, HAD, and Fawn-Hooded). After establishment of a stable baseline for alcohol intake in a continuous access paradigm, each rat received separate single i.p. injections of relatively low doses of either naltrexone (2.0 mg/kg), fluoxetine (1.0 mg/kg), the thyrotropin-releasing hormone analogue TA-0910 (0.2 mg/kg), a mixture of all three drugs, or the vehicle at 09:30. Each rat received all treatments, with an inter-injection washout period of at least 3 days. Alcohol and water intakes were measured at 6 and 24 h, and food intake was measured at 24 h, after the injection. Our results show that individual drugs did not significantly affect food, water, or alcohol intake. However, the mixture significantly reduced alcohol intake in all three strains, but had no effect on food intake. Similar results were obtained when the HAD rats received an oral dose of the individual drugs or the mixture. When P rats were given an i.p. injection of the mixture for 10 consecutive days, there was a continued suppressing effect. These findings show that a combination treatment designed to target simultaneously serotonergic, dopaminergic, and opioidergic systems can reduce alcohol intake, even though the doses of the individual drugs in the mixture are relatively low and ineffective when given singly.

Radioligand assays for oestradiol and progesterone conjugated to protein reveal evidence for a common membrane binding site in the medial preoptic area-anterior hypothalamus and differential modulation by cholera toxin and GTPgammaS.

In this study membrane oestradiol (E) binding sites in the medial preoptic area-anterior hypothalamus (MPOA-AH) of ovariectomized (OVX) rats were characterized using standard radioligand binding techniques employing E conjugated to bovine serum albumin (BSA) at position 6 and radiolabeled with 125I (E-6-[125I-BSA]). In previous studies binding of a radioactive conjugate of progesterone (P) and BSA (P-3-[125I-BSA]) was examined using the same membrane preparation. E-6-[125I-BSA] binding was linear across a tissue concentration range of 0.005-0.02 mg protein/0.1 ml of membrane suspension. An association T1/2 of 9.5 min and a dissociation T1/2 of 52.1 min for E-6-[125I-BSA] were derived from kinetic experiments. Competition binding experiments revealed high (Ki=0.63+/-(0.50 nM) and low (Ki=161.5(96.5 nM) affinity binding sites for E-6-[125I-BSA], demonstrating different binding parameters than shown in our previous work for P-3-[125I-BSA] binding. Further studies on MPOA-AH membranes treated with cholera toxin (CTX) and GTPgammaS suggested that E-6-BSA binding sites are associated with G proteins. E-6-[125I-BSA] binding demonstrated both high-and low-affinity sites. GTPgammaS added to the assay reduced both E-6-[125I-BSA] and P-3-[125I-BSA] binding suggesting that G proteins are associated with both binding sites. Extensive analysis of both E-6-[125I-BSA] and P-3-[125I-BSA] binding sites demonstrated a reciprocal relationship such that high-affinity E-6-[125I-BSA] binding sites exhibit low affinity for P-3-[125I-BSA] and low-affinity E-6-[125I-BSA] binding sites exhibit high affinity for P-3-[125I-BSA]. Preincubating membranes with CTX or GTPgammaS reduced high-affinity E-6-[125I-BSA] binding and enhanced high-affinity P-3-[125I-BSA] binding. These results suggest that, in the MPOA-AH, membrane steroid binding sites exist in two interconvertible conformations that preferentially bind either E-6-BSA or P-3-BSA, depending on their association with a G protein. Additional studies with free steroids revealed that: (1) oestrogens (17beta-oestradiol, diethylstilbestrol) as well as synthetic oestrogen antagonists tamoxifen and ICI 182 780 displaced P-3-[125I-BSA] further suggesting a relationship between membrane binding sites for E and P-3-[125I-BSA] binding sites; and (2) treatment of OVX rats with E decreased displacement by P-3-BSA and increased displacement by ICI 182,780 and tamoxifen suggesting these antagonists affect membrane P-3-[125I-BSA] binding sites after in-vivo E treatment. The membrane binding sites for E and P demonstrate interrelationships not demonstrated by their nuclear receptors.

Chronic gestational cocaine treatment decreases oxytocin levels in the medial preoptic area, ventral tegmental area and hippocampus in Sprague-Dawley rats.

We examined the effects of gestational cocaine treatment on oxytocin levels in the whole hippocampus (HIP), ventral tegmental area (VTA), medial preoptic area (MPOA) and amygdala (AMY) in rat dams on postpartum days (PPDs) 1 and 2. Cocaine treatment significantly reduced oxytocin levels in the MPOA within 12-16 h of delivery (PPD 1), but had no significant effect on the other brain areas. Oxytocin was significantly reduced in the HIP and VTA but not in the AMY or MPOA on PPD 2. These data provide the first evidence for the reduction of oxytocin levels in the VTA, HIP and MPOA as a result of gestational cocaine treatment.

Ischemic but not thermal pain sensitivity varies across the menstrual cycle.

OBJECTIVE AND METHOD: Findings from both animal and human research suggest that pain sensitivity changes across the menstrual cycle; however, among humans the nature of these menstrual cycle effects remains unclear. The present study used a repeated-measures design to evaluate changes in thermal and ischemic pain responses during three phases of the menstrual cycle, midfollicular (postmenstrual), ovulatory, and mid-to-late luteal (premenstrual), in 11 healthy women. The cycle phase during which subjects began their participation was determined randomly. Plasma levels of estrogen, progesterone, luteinizing hormone (LH), testosterone, and beta-endorphin were determined at each experimental session. Participants also completed a daily diary of physical and emotional symptoms for two complete menstrual cycles before the experimental sessions. RESULTS: The results indicated that women showed less ischemic pain sensitivity during the midfollicular compared with the ovulatory and mid-to-late luteal phases, but thermal pain responses did not vary significantly across menstrual cycle phases. Physical and emotional symptoms were minimal and did not change significantly across the menstrual cycle. CONCLUSIONS: These findings indicate greater ischemic but not thermal pain sensitivity among women after the midcycle LH surge. The practical relevance and potential mechanisms of these findings are discussed.

Thyrotropin releasing hormone analog TA-0910 suppresses alcohol intake in alcohol drinking African green monkeys.

In previous studies, we found that single injections of the thyrotropin-releasing hormone analog TA-0910 dose-dependently reduced alcohol intake and preference in alcohol-preferring (P) and Fawn-Hooded (FH) rats over a 24-hr period of continuous access to alcohol and water. However, several consecutive daily injections of TA-0910 resulted in the development of tolerance to these effects. In the present study, we found that in a 5-hr limited-access schedule in which monkeys could select an aqueous alcohol solution (7.5% v/v) or tap water, single doses of TA-0910 (0.0625, 0.125, 0.25, 0.5, and 0.75 mg/kg), similar to those found effective in P and FH rats, reduced consumption of alcohol. In this protocol, tolerance to the attenuating effects of TA-0910 on alcohol intake was not evident after five consecutive once-daily doses of 0.5 mg/kg. Furthermore, it was shown that a single dose of 0.75 mg/kg TA-0910 did not significantly influence 24-hr water intake when water was the only available fluid, but did reduce the intake of a preferred solution of saccharin. These findings suggest that activation of brain thyrotropin-releasing hormone systems reduces alcohol intake in primates and that tolerance to this effect is not evident within 5 days under a limited access schedule.

Prevalence of antithyroid antibodies in mood disorders.

We examined the prevalence of antimicrosomal and antithyroglobulin antibodies in psychiatric inpatients with unipolar depression (N = 218), bipolar disorder manic (N = 51), bipolar disorder depressed (N = 19), and bipolar disorder mixed (N = 26) in comparison with two control groups: psychiatric inpatients with adjustment disorder (N = 80) and family medicine outpatients without current psychiatric illness (N = 144). A statistical analysis that controlled for age and sex revealed the frequency of positive antibody titers not to be increased in patients with a diagnosis of unipolar depression (6.9%) or bipolar disorder manic (3.9%), when compared with patients with adjustment disorder (2.5%) and non-psychiatric subjects (6.9%). There was a weak trend toward an increased prevalence of antithyroid antibodies in patients with bipolar disorder, mixed (19%) or depressed subtype (16%). The excess occurrence of antibodies in patients with either mixed or depressed bipolar disorder did not appear to be related to lithium exposure, which was similar in all bipolar subgroups. When the intervening influences of age and sex are taken into account, unipolar depression does not appear to be associated with an excessive rate of antithyroid antibodies; however thyroid autoimmunity may be weakly associated with subtypes of bipolar disorder in which depressive symptoms are prominent.

Involvement of dopamine D2 receptors in the suppressive effect of the thyrotropin-releasing hormone analog TA-0910 on alcohol intake in alcohol-preferring rats.

Pharmacological experiments were conducted to determine the neuronal mechanisms involved in the suppressive effects of the thyrotropin-releasing hormone analog TA-0910 on alcohol intake in alcohol-preferring (P) rats. We previously reported that single intraperitoneal injections of TA-0910 dose-dependently reduced alcohol intake in P rats without altering fluid or total calorie intake; however, after several consecutive, once-daily injections, P rats developed tolerance to the suppressive effects of TA-0910 on alcohol intake and cross-tolerance to like effects of the dopamine D2 agonist bromocriptine, but not to like effects of the serotonin uptake inhibitor fluoxetine. In the present study, rats were injected with vehicle or different doses of the D2 antagonist s(-)-eticlopride (0.01 to 0.05 mg/kg) or the D1 antagonist R(+)-SCH23390 (0.1 to 0.5 mg/kg) and 20 min later with TA-0910 (0.75 mg/kg). Alcohol and water intakes were measured at 2, 4, 6, and 24 hr, and food was measured every 24 hr. Both s(-)-eticlopride and R(+)-SCH23390 produced modest reductions in alcohol intake alone; however, only s(-)-eticlopride antagonized the suppressive effect of TA-0910 on alcohol intake. In related experiments, it was confirmed that the dopamine D3 agonist 7-hydroxy-N,N-di-n-propyl-2-aminotetralin reduced alcohol intake in P rats, and it was found that tolerance to this effect did not develop during or after seven consecutive once-daily injections. Furthermore, this effect of 7-hydroxy-N,N-di-n-propyl-2-aminotetralin was not diminished in rats made tolerant to the effect of TA-0910 on alcohol intake. These data, those of previous studies, and recent preliminary findings support involvement of dopamine D2, but not D1 or D3 receptors in mediating the suppressive effect of TA-0910 on alcohol intake of P rats.

Thyrotropin-releasing hormone analog TA-0910 reduces voluntary alcohol intake of P rats subchronically in a limited scheduled access paradigm.

We previously reported that single intraperitoneal injections of the thyrotropin-releasing hormone analog TA-0910 dose-dependently reduce alcohol intake in alcohol-preferring (P) rats in a free-choice continuous access protocol. We later showed, using the same protocol, that a transient tolerance develops to this effect after several consecutive, once-daily injections. In the present study, P rats that had been accustomed to continuous access to alcohol were acclimated to a limited scheduled access protocol in which alcohol was available only between 10 and 11 AM. This resulted in an elevated rate of alcohol intake. Rats were then injected once daily with TA-0910 (0.75 mg/kg) or an equal volume of a saline vehicle at 9:45 AM for 12 consecutive days. After 11 days of scheduled access, rats were allowed continuous access to alcohol. Intake of alcohol and water was measured each day at 11:00 AM. Compared with vehicle, TA-0910 reduced alcohol intake on the 11 days of scheduled access and during the first hour of day 12 when continuous access was restored, but did not reduce total (24 hr) alcohol intake on day 12. Data from this experiment show that TA-0910 reduces alcohol intake over a long period of time in a limited scheduled access protocol.

Dose-response studies with thyrotropin-releasing hormone: evidence for differential pituitary responses in men with major depression, alcoholism, or no psychopathology.

A reduced thyrotropin (TSH) response to thyrotropin-releasing hormone (TRH) has been reported in both alcoholic and depressed men. To discern whether the pathophysiological basis of a reduced TSH response is similar in these two disorders, the present study compares the dose-response patterns of TSH and prolactin (PRL) to TRH in depressed, alcoholic, and control men. Four doses of TRH (25, 100, 500, and 800 micrograms) were given at several day intervals to 6 men with major depression, 8 men with alcohol dependence, and 7 control men. Examination of the pattern of TRH-induced TSH and PRL response revealed differences for each paired group comparison: depressed versus control, depressed versus alcoholic, and alcoholic versus control. Compared with controls, depressed men had low TSH and low PRL responses to TRH, whereas alcoholic men had low TSH responses and normal PRL responses. Levels of neither thyroid hormones, cortisol, or sex steroids, nor age or body size, explained these differences. These findings suggest that the pathophysiological basis of a reduced TSH response to TRH is different in alcoholism, compared with depression.

Estradiol conjugated to BSA releases oxytocin from synaptosome-containing homogenates from the medial preoptic area-hypothalamus.

Estradiol conjugated to bovine serum albumin at position 6(E-6-BSA) released oxytocin (OT) from homogenates of the medial preoptic area and medial hypothalamus (MPOA-MH) within minutes of its superfusion. Using a superfusion system in which synaptosome-containing homogenates were layered onto acrodiscs maintained at 37 degrees C, we have found that E-6-BSA (100 ng/microliters) superfusions significantly elevated OT release within minutes. In contrast, superfusion of the same concentration of BSA or progesterone-3-BSA (P-3-BSA) had no effect on OT release. While superfusing homogenates with augmented levels of K+ had no effect on OT release itself, superfusing E-6-BSA with these concentrations of K+ consistently increased OT release. This is the first demonstration that E-6-BSA increases OT release in a nucleus-free medium.

Analogies between oxytocin systems of the uterus and brain.

In this brief review we have compared OT systems in the brain with those of the uterus and ovary particularly with respect to interactions with steroids. We have presented evidence of heterogeneous OTR and 125I-P-3-BSA binding sites in the MPOA as well as evidence of extensive interactions of steroids and OT in the MPOA, that cannot be adequately explained by genomic effects of steroids. We also discuss a putative analogue between steroid control of OTR stimulation of intracellular calcium levels, phospholipase C activity and prostaglandins in the uterus and steroid effects on OT systems in brain. We have developed a model for steroid control of both OT release and OTR in which we suggest that steroids and OT bind to membrane receptors coupled to G proteins. This model may prove useful in understanding the interactive central actions of steroids and OT systems in regulating the endocrinology and behaviors associated with reproduction.

Thyrotropin and prolactin responses to thyrotropin-releasing hormone in young men at high or low risk for alcoholism.

A reduced thyrotropin (TSH) response to TSH-releasing hormone (TRH) has been reported in a portion of abstinent alcoholic men without evidence of cirrhosis of the liver. It is not known whether this neuroendocrine change is a precursor of alcoholism or a sequelae of heavy alcohol consumption. Three of four published studies have found evidence for differences in TRH-induced TSH response in subjects at high risk for alcoholism, based on family history, compared with subjects at low risk for alcoholism. To test further the hypothesis that the TRH-induced TSH response is a vulnerability marker for alcoholism, we tested 25 young men with an alcoholic father [family history-positive (FHP)] and matched them, on alcohol consumption, to 25 young men with no identified first- or second-degree relatives with alcoholism [family history-negative (FHN)]. FHP subjects were further categorized based on whether their father had shown signs of alcohol problems before age 25 years (FHP-Early, n = 10) or after age 24 years (FHP-Late, n = 12). FHP subjects did not differ from FHN subjects in their baseline levels of thyroid hormones, glucose, cortisol, or TSH. However, the distribution of TSH responses in the FHP subjects was skewed toward lower values, compared with FHN subjects (p = 0.12). Furthermore, FHP-Late subjects had lower TSH responses than FHN subjects (p = 0.02), whereas the TSH response of FHP-Early subjects was not different from FHN subjects. Prolactin responses to TRH were similar across all groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of progesterone-3-[125I-BSA] binding sites in the medial preoptic area and anterior hypothalamus.

In this study we utilized radiolabeled progesterone (P) conjugated to bovine serum albumin (BSA) at position 3 (P-3-[125I-BSA]) to examine steroid receptors in membrane fractions from the medial preoptic area-anterior hypothalamus (MPOA-AH) of ovariectomized (OVXed) rats. In the MPOA-AH binding of P-3-[125I-BSA] was linear across a tissue concentration range of 0.005 to 0.02 mg protein/0.1 ml of membrane suspension. Kinetic experiments revealed an association t(1/2) of 51.4 min and a dissociation t(1/2) of 122.5 min for P-3-[125I-BSA] at 0 degrees C. Analysis of data from competition binding experiments using P-3-BSA revealed high- and low-affinity binding sites in the MPOA-AH. Involvement of MPOA-AH binding sites with a G-protein was suggested by a reduction of P-3-[125I-BSA] binding in the presence of the non-hydrolyzable GTP analog GTPgammaS but not ATPgammaS. In addition, if homogenates from the MPOA-AH were preincubated with 10(-5) M of the G-protein antagonist cholera toxin for 30 min at 37 degrees C, competition binding data indicated only high-affinity binding sites. Once daily injections of OVXed rats with 4 mg P for 12 days significantly increased the density of P-3-[125I-BSA] binding sites in the MPOA-AH. This treatment did not affect P-3-[125I-BSA] binding in the dorsal tectum, medial basal hypothalamus, ventral tegmental area or the thymus.

6-sulfatoxymelatonin levels in pregnant women during workplace and nonworkplace stresses: a potential biologic marker of sympathetic activity.

Melatonin production is regulated by both catecholamines and sympathetic activity. Urine levels of the major metabolite of melatonin, 6-sulfatoxymelatonin, correlate well with serum melatonin levels and have been used to evaluate sympathetic output. We tested the hypothesis that urinary levels of 6-sulfatoxymelatonin would reflect the change in adrenergic activity on working days compared with nonworking days during pregnancy. Twenty-three healthy pregnant women, employed in a variety of occupations, including physicians, nurses, secretaries, salespeople, and laboratory workers were recruited from the clinics of the University of North Carolina School of Medicine. We measured 6-sulfatoxymelatonin levels in first morning voids and for the subsequent 10 hours at 24, 28, 32, and 36 weeks' gestation. Urine was collected in sets during working days and during nonworking days. 6-Sulfatoxymelatonin was measured by radioimmunoassay. In 11 women we also measured urine catecholamines by high-performance liquid chromatography. Levels of 6-sulfatoxymelatonin output did not change across gestation, although they tended to drift down as pregnancy progressed. Median levels at first morning void were 6.3 micrograms on workdays and 4.6 micrograms on nonworkdays. Although all values were skewed toward work being greater than nonwork, there were large interindividual variations. We therefore compared subjects against themselves and compared work levels for each subject to the corresponding gestational age-matched nonwork value. Among the 23 women, median 6-sulfatoxymelatonin levels were 81% greater during work than nonwork (p < 0.0002) when first morning collections were compared. Daytime urinary excretion of 6-sulfatoxymelatonin on workdays was 38% (p < 0.005) greater than during nonworkdays.(ABSTRACT TRUNCATED AT 250 WORDS)