Indolamines

Abstract: Bright-light therapy (BLT) is established as the treatment of choice for seasonal affective disorder/winter type (SAD). In the last two decades, the use of BLT has expanded beyond SAD: there is evidence for efficacy in chronic depression, antepartum depression, premenstrual depression, bipolar depression and disturbances of the sleep-wake cycle. Data on the usefulness of BLT in non-seasonal depression are promising; however, further systematic studies are still warranted. In this review, the authors present a comprehensive overview of the literature on BLT in mood disorders. The first part elucidates the neurobiology of circadian and seasonal adaptive mechanisms focusing on the suprachiasmatic nucleus (SCN), the indolamines melatonin and serotonin, and the chronobiology of mood disorders. The SCN is the primary oscillator in humans. Indolamines are known to transduce light signals into cells and organisms since early in evolution, and their role in signalling change of season is still preserved in humans: melatonin is synthesized primarily in the pineal gland and is the central hormone for internal clock circuitries. The melatonin precursor serotonin is known to modulate many behaviours that vary with season. The second part discusses the pathophysiology and clinical specifiers of SAD, which can be seen as a model disorder for chronobiological disturbances and the mechanism of action of BLT. In the third part, the mode of action, application, efficacy, tolerability and safety of BLT in SAD and other mood disorders are explored.

Abstract: The mammalian pineal hormone melatonin (N-acetyl-5-methoxytryptamine), an aminoindole produced by the metabolism of serotonin (5-hydroxytryptamine), has been shown to be a potent scavenger for the highly toxic hydroxyl radical. Three substances that are very important in animal physiology (e.g., in brain metabolism) are noradrenaline, histamine, and serotonin; all three occur in plants. Here we report that serotonin, tryptamine, and melatonin were found in some edible and medicinal plants in Egypt. The results of this screening showed that the pulp of underripe and ripe yellow banana contains 5-hydroxytryptamine at concentrations of 31.4 and 18.5 ng/g, respectively. Corn, rice, barley grains, and ginger showed the highest concentrations of melatonin, at 187.8, 149.8, 87.3, 142.3 ng/100 g, respectively. On the other hand, potato samples were free from all indolamines. Pomegranate and strawberry showed a low level of indolamines (8-12 microg/g serotonin, 4-9 microg/g tryptamine, and 13-29 ng/100 g melatonin).

Abstract: To determine the effect of biogenic amines on LH release in rats, blood samples were drawn by cardiac puncture in etheranesthetized animals bearing chronic cannulae in the third ventricle (3rd V) immediately before and 15 min after intraventricular injection of various drugs. In the interim between removal of the 2 blood samples the rats recovered from anesthesia. Plasma LH was measured by radioimmunoassay. Serotonin (5-HT) did not alter plasma LH levels significantly at any stage of 4-day estrous cycles. Norepinephrine (NE) also failed to produce over-all significant changes in plasma LH although there were some positive responses. Dopamine (DA) raised LH to levels as high as 8- or 10-fold above controls (p<.01) in rats on the 2nd day of diestrus (D2) or in proestrus (P). DA proved to be less effective in Dl or estrus (E). In normal males DA raised plasma LH in 5 out of 9 animals (p<.02), whereas NE was ineffective. The effect of DA in D2 and P rats could be blocked by simultaneous 3rd V injection of 30 ...