Abnormal thyroid stimulating hormone, prolactin, and growth hormone responses to thyrotropin releasing hormone in abstinent alcoholic men with cerebral atrophy

Dysregulation of the hypothalamic-pituitary-thyroid axis in alcoholism

Thyroid dysfunction is a prominent finding in alcoholism. Subclinical and clinical hypothyroidism have been associated with clinical depression and cognitive impairment and may increase the relapse risk among alcoholics. In spite of these important clinical associations, there is no consensus on thyroid dysfunction in alcoholism in the literature. In this paper, we present a review of the literature and develop a hypothesis that may explain dysfunction of the hypothalamic-pituitary-thyroid axis in alcoholism. Based on a Medline research of the years 1980-2001 we found 33 empirical studies that assessed thyroid function in alcoholism. The most consistent findings were a reduction in total thyroxine and total and free triiodothyronine concentrations during early abstinence. About one-third of all alcoholics also displayed a blunted thyroid stimulation hormone (TSH) response in the thyrotrophin-releasing hormone test (TRH-test). Blunting was observed frequently during detoxification, but was also present in some alcoholics after several weeks of abstinence. We suggest that a reduction in peripheral thyroid hormones may be caused by a direct toxic effect of alcohol on the thyroid gland, which induces a central compensatory activation of the hypothalamic-pituitary axis with an increased TRH release. The TRH release induces a downregulation of pituitary TRH receptors, which manifest as a blunted TSH response to the TRH test. We discuss further additional effects of alcohol on thyroid-hormone metabolizing deiodinases and on monoaminergic systems, which may interact directly with mood states among abstinent alcoholics.

Daytime alertness, mood, psychomotor performances, and oral temperature during Ramadan intermittent fasting

During the month of Ramadan, Moslems abstain from drinking and eating daily between sunrise and sunset. This change of meals schedule is accompanied with changes in sleep habit, which may affect diurnal alertness. This study examined the effect of Ramadan intermittent fasting on the diurnal alertness and oral temperature in 10 healthy young subjects. The cognitive task battery including movement reaction time (MRT), critical flicker fusion (CFF) and visual analogue scale, was administered at 6 different times of the day: 09.00, 11.00, 13.00, 16.00, 20.00 and 23.00 h on the 6th, 15th, and 28th days of Ramadan. The baseline day was scheduled one week before Ramadan, and the recovery day 18 days after this month. Oral temperature was measured prior to each test session and at 00.00 h. During Ramadan oral temperature decreased at 09.00, 11.00, 13.00, 16.00 and 20.00 h and increased at 23.00 and 00.00 h. Subjective alertness decreased at 09.00 and 16.00 h and increased at 23.00 h. Mood decreased at 16.00 h. MRT was increased at the beginning of Ramadan (R6) and CFF was not changed. These results showed that daytime oral temperature, subjective alertness and mood were decreased during Ramadan intermittent fasting.

Prolactin secretion in lactating rats following chronic alcohol exposure: provocative tests with secretagogues

This study was done to examine the mechanism of action of alcohol in inhibiting suckling-induced prolactin release in the lactating rat. Alcohol (0.0, 1.0 or 2.0 g/kg body weight) was administered daily for 8 days from day 5 to 12 of lactation via an indwelling atrial catheter, implanted on day 3 of lactation. Following the administration of the initial alcohol dose, infusion was continued at rates required to maintain the blood alcohol levels (BALs) for four hours every day. Prolactin responses to sulpiride and TRH were tested on day 12. Alcohol administration for 8 days and maintaining the blood alcohol levels for four hours daily did not affect the basal or sulpiride and TRH-stimulated plasma prolactin release. Since the prolactin releasing capacity of pituitary lactotropes of the lactating rat is not compromised following chronic alcohol exposure, we conclude that alcohol does not act at the anterior pituitary level to inhibit the suckling induced prolactin release but probably acts by other mechanisms: either via the hypothalamic and/or higher central nervous system or by disrupting the neural impulse transmission, engendered at the nipples in response to suckling.

Cerebral atrophy and plasma cortisol levels in alcoholics after short or a long period of abstinence

Basal cortisol levels were significantly lower in 4 week abstinent alcoholics (n = 11; group A) than in normal controls (n = 9; group C), whereas no significant difference was found between alcoholics abstinent greater than 1 year (n = 9; group B) and controls. In all groups, dexamethasone induced a similar decrease in circulating cortisol concentrations. Computed tomographic examinations showed a significantly higher ventricular-brain ratio VBR) and wider 3rd ventricle width in group A than in group B; no significant differences were observed between groups B and C. In contrast, the number of cerebral sulci was similar in all groups. A negative relationship was found between neuroradiological findings and basal cortisol values in group A, but not in groups B and C. The neuropsychological tests showed worse scores in group A than in the other groups. These findings show subcortical damages and reduced cortisol levels in alcoholics after 4 weeks of abstinence. These alterations appear to be at least in part reversible after a long period of abstinence.

Hypothalamic-pituitary-thyroid (HPT) axis in chronic alcoholism. I. HPT axis in chronic alcoholics during withdrawal and after 3 weeks of abstinence

Thyroxine (T4), free T4 (fT4), triiodothyronine (T3), free T3 (fT3), reverse T3 (rT3), thyrotropin (TSH), thyroxine binding globulin (TBG), and T3 uptake were measured in 14 chronic alcoholics during withdrawal and after 21 days of abstinence. Results were compared with those of 16 healthy volunteers. During withdrawal, the fT4 and fT3 concentrations were subnormal, whereas the respective protein-bound fractions were normal. T4, T3, and TBG increased during the abstinence period, T3 and TBG being significantly higher than in normals at the second measuring time. T3 uptake values fell, but remained well within the normal range at both measuring times. During abstinence, the fT3 levels remained significantly lower than in healthy subjects. rT3 concentrations decreased, but not significantly. The TSH values were normal throughout. These results showed numerous abnormalities in the hypothalamic-pituitary-thyroid axis in alcoholics, the reasons for which are as yet unclear. The following possible interpretations are suggested: 1. The abnormally low serum fT3 and fT4 levels during withdrawal might reflect an increase in tissue uptake. 2. The increases in T4--and partly those in T3--during abstinence seem to reflect increased binding by TBG, the level of which rose markedly for reasons as yet unknown. 3. If increases in TBG during abstinence are taken into account, the decreases in rT3 concentrations may reach the level of statistical significance. These falls in rT3 concentrations may reflect an increase in rT3 metabolization (deiodination) in various tissues, including the CNS, leading to a reduction in serum rT3 bioavailability. 4. Factors such as liver disease, protein caloric malnutrition, and "psychological stress" do not fully explain all these abnormalities. A direct effect of ethanol on intracellular thyroid hormone metabolism and/or function seems conceivable.

Alcohol effects on TRH-induced prolactin response in lactating rats: in vivo and in vitro studies

The site of action of alcohol in inhibiting suckling-induced prolactin release in lactating rats was examined by in vivo and in vitro studies. In vivo, sulpiride- and thyrotropin-releasing hormone (TRH)-induced prolactin release was studied in lactating rats separated from their litter. On day 7, dams were implanted with an atrial catheter. On day 10, pups were removed from dams at 0800 h and, after 5 h, an extension was attached to the catheter. An hour later, a baseline blood sample was removed and was followed by sulpiride (40 micrograms/kg) administration. Additional blood samples were withdrawn over 1 h. After the 60-min sample, sulpiride-administered rats were infused with 0.0, 1.0, or 2.0 g/kg b.wt. alcohol. Following alcohol, a postinfusion blood sample was removed, TRH (4.0 micrograms/kg) was administered, and subsequent blood samples were obtained 5, 10, 20, and 30 min after TRH. For in vitro studies, cells from lactating rats in midlactation were enzymatically dissociated, plated, and on culture day 5 were exposed to 0 or 10 nM TRH. Each set of cells were additionally exposed to 0, 100, or 300 mg% alcohol and media harvested after 4 h. In a subsequent study, plated cells were exposed to increasing doses of TRH in the presence of 0, 100, or 300 mg% alcohol and media harvested as above. Prolactin in plasma (in vivo studies) and medium (in vitro studies) was measured by RIA.(ABSTRACT TRUNCATED AT 250 WORDS)

Thyroid stimulating hormone and prolactin responses to thyrotropin releasing hormone in nondepressed alcoholic inpatients

Thyroid stimulating hormone (TSH) and prolactin (PRL) responses to thyrotropin releasing hormone (TRH) stimulation are sometimes blunted in alcoholic subjects; however, the mechanisms involved in these phenomena have not been established. We hypothesized that elevations in free thyroid concentrations might be related to these abnormal responses and then tested that hypothesis in a sample of nondepressed alcoholic inpatients (n = 21). Four alcoholic patients had delta max TSH responses that were < 7 mIU/l; three had PRL responses at or below 8 micrograms/l. Baseline TSH was the only significant predictor of peak TSH; however, free thyroxine (FT4) and baseline TSH both were significant predictors of peak PRL. The average baseline FT4 concentration in alcoholic patients was significantly higher than that in healthy control subjects (n = 10). Our data, thus, suggest that small elevations of FT4 play a role in the inhibition of TSH and PRL responses to TRH among nondepressed, abstinent alcoholic patients.