Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of oral caffeine (3.3 mg/kg, equivalent to 2-3 cups of coffee) on plasma adrenocorticotropin (ACTH) and cortisol (CORT) were tested in 47 healthy young men at rest in a double-blind, placebo-controlled, crossover study. Following caffeine, ACTH was significantly elevated at all times from 30 min to 180 min, and CORT was elevated from 60 min to 120 min (Fs > or = 8.4, ps < 0.01). Peak increases relative to placebo were: ACTH, 33% (+5.2 pg/ml) and CORT, 30% (+2.7 micrograms/dl) at 60 min postcaffeine. The results suggest that caffeine can activate important components of the pituitary-adrenocortical response in humans during the resting state. Caffeine's known ability to increase CORT production appears at least partly due to an increase in ACTH release at the pituitary.
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PMID:Stress-like adrenocorticotropin responses to caffeine in young healthy men. 895 77

Pharmacological challenge paradigms have been useful for elucidating the phenomenology and neurobiology of panic attacks. A drawback of the pharmacological challenge method is that individual differences in baseline arousal and outcome expectancy can lead to different subjective and physiological drug responses. One method for eliminating differences in baseline arousal and expectancy is to perform pharmacological challenges during non-rapid eye movement (non-REM) sleep. In the present study, fourteen healthy male volunteers received caffeine (5 mg/kg) and placebo (normal saline) during non-REM sleep on two successive nights, in a single-blind manner. Caffeine, compared to placebo, was associated with increased arousal, sleep disruption, and elevations in adrenocorticotropic hormone (ACTH) and cortisol. In one subject, caffeine infusion during sleep induced a panic attack. These findings indicate that caffeine leads to increased arousal and hypothalamic-pituitary-adrenal axis (HPA) axis activation in the absence of high baseline anxiety and expectancy bias. Further, they suggest that similar techniques can be employed in patient populations to elucidate the neurobiology of sleep panic attacks.
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PMID:Effects of intravenous caffeine administered to healthy males during sleep. 925 Apr 37

The present study was conducted to evaluate the effects of caffeine and the benzodiazepine agonist diazepam, and a combination of both on beta-endorphin (beta-EN) levels in specific rat brain regions. Male Sprague-Dawley rats (150-200 g) adapted to a 12-hour light: 12-hour dark illumination cycle were used in this study. Caffeine (10 mg/kg), diazepam (2 mg/kg) or a combination of caffeine (10 mg/kg) and diazepam (2 mg/kg) were administered intraperitoneally to rats at 11:00 hr. Control animals were injected with saline. Animals were sacrificed by decapitation 1 h after injection, the brains were immediately removed; the cortex, hippocampus, hypothalamus and midbrain were dissected and their B-EN levels measured by radioimmunoassay. Caffeine administration significantly increased B-EN levels in the cortex. Similarly, administration of diazepam alone resulted in a significant increase of B-EN levels in cortex. However, concurrent administration of diazepam and caffeine resulted in higher increase of B-EN levels in cortex. No significant changes in B-EN levels were detected in hippocampus and midbrain after administration of either caffeine or diazepam alone. On the other hand, when diazepam and caffeine were concurrently administered a significant increase of B-EN levels were observed in the midbrain. Moreover, administration of diazepam alone resulted in a significant increase of B-EN levels in hypothalamus. This increase was still observed following concurrent administration of diazepam and caffeine. These results clearly indicate that diazepam alters caffeine-induced effects on B-EN in specific rat brain regions.
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PMID:Diazepam alters caffeine-induced effects on beta-endorphin levels in specific rat brain regions. 941 67

Recent research indicates that the sensitization that results from repeated drug or non-drug stress exposure may develop into a pattern of alternating increases and decreases (i.e., oscillation) in response to each subsequent stressor exposure. Oscillation, with or without prior sensitization, has been observed for a number of drug and non-drug stressors, and for various neurochemical and endocrine endpoints. The present studies investigated whether oscillation also occurs in the behavioral and endocrine effects of repeated morphine treatment and if a drug that normalizes the mood swings of bipolar disorder in humans will also attenuate drug oscillation in this animal model. In the first experiment, rats were given 1-5 pretreatments with morphine (15 mg/kg, i.p.), separated by 1-week intervals with the last injection occurring 1 hour prior to being tested for stressor-induced (i.e., 5 seconds, 2-mA electric footshock) hypoalgesia, as measured by latency to paw-lift or jump from a hot-plate. Plasma beta-endorphin also was measured. The second experiment replicated the behavioral findings of the first study and, in addition, assessed the effect of continuous lithium chloride, in the drinking water, on morphine-induced oscillation. Caffeine was used as a partial control for the lithium. The results were that one injection of morphine enhanced stress-induced hypoalgesia and subsequent morphine administrations resulted in oscillation. Beta-endorphin exhibited sensitization but not oscillation, suggesting that it did not mediate oscillation of the behavioral response. In addition, lithium, but not caffeine, eliminated oscillations of the behavioral response without affecting its initial enhancement.
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PMID:Oscillatory effects of repeated morphine on shock-induced hypoalgesia and beta-endorphin. 970 78

To examine the effect of caffeine ingestion on muscle glycogen utilization and the neuroendocrine axis during exercise, we studied 20 muscle glycogen-loaded subjects who were given placebo or caffeine (6 mg/kg) in a double blinded fashion 90 min before cycling for 2 h at 65% of their maximal oxygen consumption. Exercise-induced glycogen depletion in the thigh muscle was noninvasively measured by means of 13C nuclear magnetic resonance spectroscopy (NMR) spectroscopy, and plasma concentrations of substrates and neuroendocrine hormones, including beta-endorphins, were also assessed. Muscle glycogen content was increased 140% above normal values on the caffeine trial day (P < 0.001). After cycling for 2 h, caffeine ingestion was associated with a greater increase in plasma lactate (caffeine: +1.0 +/- 0.2 mmol/L; placebo, +0.1 +/- 0.2 mmol/L; P < 0.005), epinephrine (caffeine, +223 +/- 82 pg/mL; placebo, +56 +/- 26 pg/mL; P < 0.05), and cortisol (caffeine, +12 +/- 3 mg/mL; placebo, +2 +/- 2 mg/mL; P < 0.001) levels. However, plasma free fatty acid concentrations increased (caffeine, +814 +/- 133 mmol/L; placebo, +785 +/- 85 mmol/L; P = NS), and muscle glycogen content decreased (caffeine, -57 +/- 6 mmol/L muscle; placebo, -53 +/- 5 mmol/L muscle; P = NS) to the same extent in both groups. At the same time, plasma beta-endorphin levels almost doubled (from 30 +/- 5 to 53 +/- 13 pg/mL; P < 0.05) in the caffeine-treated group, whereas no change occurred in the placebo group. We conclude that caffeine ingestion 90 min before prolonged exercise does not exert a muscle glycogen-sparing effect in athletes with high muscle glycogen content. However, these data suggest that caffeine lowers the threshold for exercise-induced beta-endorphin and cortisol release, which may contribute to the reported benefits of caffeine on exercise endurance.
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PMID:Effects of caffeine on muscle glycogen utilization and the neuroendocrine axis during exercise. 1085 47

The neuropeptides, monoamines and many drugs involved with modulating food intake and fat stores have reciprocal effects on sympathetic activity and thermogenesis. Both serotonin, acting through 5HT1B/2C receptors, and norepinephrine acting through beta2 and/or beta3 receptors reduce food intake and augment sympathetic activity. Neuropeptide Y, beta-endorphin, orexin, galanin and melanin concentrating hormone all increase food intake and, where tested, reduce sympathetic activity. In contrast, a larger number of peptides including cholecystokinin, corticotrophin-releasing hormone/urocortin, enterostatin, leptin, CART and alpha-MSH reduce food intake and increase sympathetic activity. Nicotine, prostaglandin, dexfenfluramine and sibutramine also have this reciprocal effect on feeding and sympathetic nervous system (SNS) activity. Chronic administration of neuropeptide Y (NPY) can produce chronically increased food intake and obesity. This syndrome is similar to the ventromedial hypothalamus (VMH) syndrome and suggests that NPY must be acting as an inhibitory signal to stimulate a feeding system and inhibit sympathetic activity. The melanocortin receptor system may be particularly important in modulating food intake, because a transgenic mouse which does not express melanocortin-4 receptors is massively overweight. Adrenal glucocorticoids are important in obesity since adrenalectomy will reverse or prevent the development of all forms of obesity. The clinical importance of the sympathetic nervous system and food intake is emphasized by the inverse relation of sympathetic activity and body fat. The inhibition of food intake, lower body fat stores and higher energy expenditure in smokers also support this hypothesis. The reciprocal relationship between food intake and sympathetic activity is robust, suggesting that beta receptors in the periphery and brain may be involved in the control of feeding and a reduction in food intake in humans accounts for most of the weight loss with ephedrine and caffeine. We conclude that the inhibition of feeding by activating the SNS is an important satiety system which helps regulate body fat stores.
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PMID:Reciprocal relation of food intake and sympathetic activity: experimental observations and clinical implications. 1099

It has been suggested that the endogenous opioid system, especially beta-endorphins, may play an important role in the behavioral effects of ethanol. The main site of beta-endorphin synthesis in the brain is the hypothalamic arcuate nucleus (ARC). In the present study, we used the neurotoxins monosodium glutamate (MSG) or goldthioglucose (GTG) to produce a selective ARC lesion and to assess its effects on the locomotion observed after ethanol administration. The results show that MSG or GTG pre-treatment produces a blockade of the increased locomotion produced by the injection of low and moderate doses of ethanol (0.5 and 1.5 g/kg, respectively). These effects were observed in the absence of any change in blood ethanol levels. On the other hand, MSG (but not GTG) pre-treatment enhanced the locomotor depression produced by higher doses of this alcohol (2.5 g/kg). Finally, caffeine (10 mg/kg)-induced locomotion was unaffected by the aforementioned neurotoxic agents. Thus, taken together, the present results suggest that MSG and GTG administration produce a blockade of the stimulating effects of ethanol on locomotion in mice and thus provides further support for a role of the ARC in the behavioral effects observed after ethanol administration.
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PMID:Consequences of monosodium glutamate or goldthioglucose arcuate nucleus lesions on ethanol-induced locomotion. 1223 48

Anterior pituitary corticotropes show a wide repertory of responses to hypothalamic neuropeptides and adrenal corticosteroids. The hypothesis that plasticity of the cAMP signaling system underlies this adaptive versatility was investigated. In dispersed rat anterior pituitary cells, depletion of intracellular Ca2+ stores with thapsigargin combined with ryanodine or caffeine enhanced the corticotropin releasing-factor (CRF)-evoked cAMP response by 4-fold, whereas reduction of Ca2+ entry alone had no effect. CRF-induced cAMP was amplified 15-fold by arginine-vasopressin (AVP) or phorbol-dibutyrate ester. In the presence of inhibitors of cyclic nucleotide phosphodiesterases and phorbol-dibutyrate ester, the depletion of Ca2+ stores had no further effect on CRF-induced cAMP accumulation. Adenohypophysial expression of mRNAs for the Ca2+-inhibited adenylyl cyclases (ACs) VI and IX, and the protein kinase C-stimulated ACs II and VII was demonstrated. ACIX was detected in corticotropes by immunocytochemistry, whereas ACII and ACVI were not present. The data show negative feedback regulation of CRF-induced cAMP levels by Ca2+ derived from ryanodine receptor-operated intracellular stores. Stimulation of protein kinase C by AVP enhances Ca2+-independent cAMP synthesis, thus changing the characteristics of intracellular Ca2+ feedback. It is proposed that the modulation of intracellular Ca2+ feedback in corticotropes by AVP is an important element of physiological control.
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PMID:Short-term plasticity of cyclic adenosine 3',5'-monophosphate signaling in anterior pituitary corticotrope cells: the role of adenylyl cyclase isotypes. 1255 75

The effect of colchicine was studied on the rapid, reversible darkening of frog skin under the influence of melanocyte-stimulating hormone (MSH). Darkening is due to dispersion of melanin granules in melanocytes and is thought to be accompanied by a gel-to-sol cytoplasmic transformation. After subsequent washing, the skin lightens, with aggregation of melanin granules and cytoplasmic gelation. Preincubation of skin with colchicine had the following effects: 1. Darkening induced by MSH was increased in comparison to control skins, and on removal of MSH, lightening was inhibited. Inhibition was a function of both concentration (1 x 10(-5) to 9 x 10(-5)M) and exposure time (2 to 30 minutes). Once established, inhibition was maintained throughout the remainder of the experiment. 2. The same effects were noted (a) when darkening was effected by agents other than MSH (ATP) 0.9 x 10(-3)M; caffeine, 5.2 x 10(-3)M; ethyl acetate, 0.8 x 10(-2)M), and (b) when lightening was effected by addition of chemical agents (melatonin, 4.3 x 10(-10)M; hydrocortisone, 1 x 10(-3)M; norepinephrine, 1 x 10(-3)M), instead of by washing. 3. Colchicine alone produced a gradual, irreversible, dosage-dependent darkening over several hours. This darkening was inhibited by melatonin, 4.3 x 10(-10)M. The melanocyte model is used to construct a general theory of colchicine action on living cells, an action resulting in decreased protoplasmic viscosity. In this formulation colchicine lowers the potential limit of protoplasmic gelation, and does it rapidly, reversibly, in low concentration, in a dosage-dependent manner, and without killing the cell. The theory allows interpretation of "synergism" and "antagonism" to colchicine by other substances. It suggests a tentative approach to the understanding of colchicine action in acute gouty arthritis, where interference with ameboid activities of polymorphonuclear leukocytes is one possible aspect of the anti-inflammatory effect of colchicine. Finally, the colchicine-treated melanocyte is viewed as a good, live physical model that can be used to elucidate some fundamental biological properties.
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PMID:ON THE ACTION OF COLCHICINE, THE MELANOCYTE MODEL. 1431 40

Although caffeine is the most consumed psychoactive substance in the world, the extents of many of its effects are unknown. High doses of caffeine have been shown to activate the HPA axis while the effects of low to moderate doses have usually not been described in detail. Moreover, although several lines of evidence suggest that low doses of caffeine may restrain some negative affective states, the possible modulatory role of caffeine on HPA axis activation induced by a stressful stimulus has not been described. Thus, the present studies investigated the possible modulatory effects of low to moderate doses of caffeine on moderate to high HPA axis activation induced by different intensities of loud noise. First, in order to test this modulation, time courses for adrenocorticotropic hormone (ACTH) and corticosterone responses to loud noise stress and to caffeine were defined, in rats. Plasma ACTH and corticosterone levels peaked 30 min from the onset of noise presentation, and rapidly declined after noise termination. A low caffeine dose of 2 mg/kg significantly increased plasma corticosterone and ACTH levels 30 min following injections, but levels returned to baseline 60 min following injections. Caffeine doses of 30 mg/kg and higher elevated plasma hormone levels for at least 2h. Doses of 2 or 10mg/kg, however, did not modulate endocrine responses to loud noise presentation. It is concluded that although caffeine activates the HPA axis, low to moderate doses do not modulate HPA axis responses to stressful stimuli.
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PMID:Modulation of the hypothalamo-pituitary-adrenocortical axis by caffeine. 1641 73


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