Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Day and nighttime melatonin production in the pineal gland was compared in normal and cardiomyopathic (polydystrophic) adult male Syrian hamsters. These strains of hamsters were selected for comparison because the cardiomyopathetic hamster displays a deficient transmembrane Ca(2+)-pump in a number of tissues, and intracellular CA2+ concentrations ([Ca2+]i) play a central role in the nocturnal increase in pineal melatonin synthesis. Daytime levels of all constituents measured, i.e., pineal N-acetyltransferase (NAT) activity, pineal and serum melatonin levels, and pineal 5-hydroxytryptophan (5-HTP), serotonin, and 5-hydroxyindole acetic acid (5-HIAA) contents, were comparable in control and dystrophic hamsters. In contrast, the nighttime rises in pineal NAT activity and pineal and serum melatonin levels were significantly attenuated in the dystrophic hamsters. By comparison, the pineal contents of 5-HTP, serotonin, and 5-HIAA were essentially the same in both groups of hamsters with both pineal serotonin and 5-HIAA values exhibiting the usual nighttime drop. It is presumed that the alterations in nocturnal melatonin production in the pineal gland of the cardiomyopathic hamster may relate to a generalized deficiency in the Ca(2+)-pump in pinealocyte plasma membranes, which leads to unusually high [Ca2+]i, causing a depression of NAT activity; this leads to the commensurate decline in pineal and serum melatonin levels. Harderian gland NAT activity and melatonin levels were essentially similar in the two groups of animals, although NAT activity was slightly depressed in the dystrophic hamsters killed during the day. The reduced amounts of intrascapular brown fat in the cardiomyopathic hamster is speculated to be a result of the diminished amount of melatonin produced in these animals.
J Pineal Res
PMID:Attenuated nocturnal rise in pineal and serum melatonin in a genetically cardiomyopathic Syrian hamster with a deficient calcium pump. 172 60

The synthesis of the cytoskeletal protein actin exhibits, in the rat hypothalamus, a diurnal variation with maxima during morning hours. The objective of the present study was to assess whether melatonin injection could affect the in vitro incorporation of 35S-methionine into actin, as well as the levels of actin mRNA, in the hypothalamus of adult male rats treated either acutely or chronically with the hormone at 10:00 or 18:00. Injection of 100 micrograms/kg of melatonin for ten days at either time induced a significant depression in the incorporation of 35S-methionine into a 43 kDa protein with the electrophoretic mobility of actin. The specific activity of total soluble proteins after labeled methionine incubations decreased only after evening melatonin administration (100 micrograms/kg, ten days). Hypothalamic actin mRNA levels, quantitated by dot-blot analysis, decreased only after the injection of 100 micrograms/kg melatonin for ten days at 10:00. Neither a 10-micrograms/kg dose of melatonin, nor a single injection of 100 micrograms/kg melatonin, caused any significant change in the parameters examined. Melatonin (100 micrograms/kg for ten days) did not modify hypothalamic somatostatin or H-Ras mRNA concentration. These results suggest the existence of an inhibitory effect of melatonin on hypothalamic actin synthesis.
J Pineal Res 1990
PMID:Time-dependent effect of melatonin on actin mRNA levels and incorporation of 35S-methionine into actin and proteins by the rat hypothalamus. 197 1

The human dark phase melatonin concentrations exhibit a wide range of values. In an attempt to explain this variation, we measured 2250-2305 h melatonin levels by radioimmune assay in eleven fast and eleven slow acetylator phenotypes. No statistical difference between the two groups existed, suggesting therefore that such variations are not due to acetylator status. The study revealed a negative relationship between body weight or area and nocturnal melatonin concentration. No correlation was found between dark phase melatonin levels and age, anxiety, depression, or sleep rating.
J Pineal Res 1991 Jan
PMID:Human nocturnal blood melatonin and liver acetylation status. 205 26

After chronic administration of epithalamin (a pineal peptide drug), an increase in the amplitude and shifts in the acrophase of rat's circadian locomotor activity to late hours were observed. These results were obtained only in rats with low initial amplitude of their circadian rhythm. Epithalamin also changed the time-course of forced swimming and decreased the rhythmic index of depression. These observations suggest that the pineal gland of the rat, via its peptides, may prevent the development of depressive-like events.
J Pineal Res 1990
PMID:Chronic administration of pineal peptides change the circadian locomotor activity and time-course of forced swimming in rats. 209 96

The object of this study was to compare the effects of short photoperiod (SP) and melatonin (MEL) treatment on the reproductive axis in ovariectomized LSH/SsLak hamsters. Animals acclimatized in long photoperiods (LP) (14L:10D) and showing regular estrous cycles were ovariectomized. Half of the operated hamsters received Silastic capsules containing 17-beta estradiol (E2). On the following day the animals were further subdivided into three groups: the animals in one group received daily afternoon injects of melatonin (MEL), those in a second group were given the vehicle, and animals in the third group were transferred from LP to SP (8L:16D). All animals were killed after 30 days. In hamsters without E2 replacement, MEL or SP exposure significantly suppressed serum and pituitary FSH levels, although MEL was more effective in this regard. On the other hand, SP exposure did not change serum FSH levels in animals with E2 implants, whereas MEL effectively suppressed them. SP or MEL reduced serum LH levels to a similar extent in the absence of E2 replacement, yet in animals with E2 implants only MEL significantly lowered LH levels below LP E2-treated controls. This was in contrast to effects on the pituitary where both treatments were equally effective in the depression of LH content. Serum PRL levels were similarly suppressed by MEL or SP exposure in E2-treated hamsters. On the other hand, pituitary PRL levels were not affected by either treatment in animals with E2-containing capsules, whereas SP or MEL treatment both significantly depressed pituitary PRL contents in hamsters without E2 replacement. SP treatment lowered MBH LHRH contents in animals with E2-containing capsules; no other significant changes in hypothalamic LHRH were noted. The data suggest that daily treatment with 25 micrograms of MEL is generally more effective in the suppression of gonadotropin levels than SP exposure. It is suspected that the mode of administration of MEL, and its quantity, may interact with estrogen differently than SP in the induction of physiological changes and regulation of the LHRH system.
J Pineal Res 1989
PMID:Comparison of the effects of short photoperiod exposure and melatonin treatment in ovariectomized LSH/SsLaK hamsters. 250 75

Numerous endocrine abnormalities are found in depressive illness and, among these, several have been proposed as useful markers in diagnosis, prediction of treatment response, monitoring treatment outcome or in understanding of etiology. This paper reviews five endocrine systems--the hypothalamic-pituitary-adrenal axis, hypothalamic-pituitary-thyroid axis, growth hormone regulation, prolactin regulation and pineal function, in which such abnormalities have been reported. The dexamethasone suppression test (DST) results are affected by a variety of other diseases and confounding conditions. Furthermore, variability in dexamethasone availability has recently been shown to be an important factor, influencing post-DST cortisol levels. Refined tests, taking into account all these factors, or alternative tests of hypothalamic-pituitary-adrenal function may lead to improved clinical utility. Pineal function is now the focus of considerable investigation. Low nocturnal output of melatonin is found in unipolar and bipolar affective disorder and is normalized by treatment with antidepressant drugs which block re-uptake of noradrenaline. These findings support the hypothesis of noradrenergic abnormality in depression. In seasonal affective disorder there is evidence for a phase delay in the melatonin rhythm which may be a key factor in the seasonal disorder. Effective light therapy causes a phase advance in the abnormal melatonin rhythm. Whether the normalization of the melatonin rhythm is instrumental in producing the antidepressant effect is yet to be determined. There are wide spread neuroendocrine abnormalities in depressive illness. These abnormalities encompass many different pituitary hormones, as well as the pineal.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Neuroendocrine probes as biological markers of affective disorders: new directions. 268 81

In a previous work, pinealectomy was found to depress benzodiazepine (BZP) receptor binding in cerebral cortex membranes of rats killed at noon. In order to assess the effect of pineal removal on diurnal variations of BZP binding site concentration and affinity, groups of intact, pinealectomized, or sham-pinealectomized rats (subjected to surgery 2 wk earlier) were killed at six different time intervals during the 24-h cycle. BZP binding was assessed by Scatchard analysis of 3H-flunitrazepam high-affinity binding to cerebral cortex membranes. In intact and sham-pinealectomized rats, a maximum in BZP receptor concentration was found at midnight. Pinealectomy blunted the nocturnal peak of receptor concentration and caused a significant depression of binding site number at noon. No changes in the affinity of the binding sites for the radioligand were detected as a function of time of day or following surgery. In a dose-response experiment for melatonin ability to restore the depressed BZP receptor concentration of cerebral cortex membranes of pinealectomized rats killed at noon, a minimal effective dose of 25 micrograms/kg body weight was obtained. These results further support a link between pineal activity and brain BZP receptors in rats.
J Pineal Res 1986
PMID:Diurnal variations of benzodiazepine binding in rat cerebral cortex: disruption by pinealectomy. 301 9

Residency training may disrupt normal sleep/wake cycles, resulting in mood and performance deficits and alterations in biological rhythms. To characterize such disturbances and determine whether they are associated with an alteration in the day/night pattern of melatonin excretion, measurements were obtained around-the-clock in seven male subjects, each studied in two 48-h sessions. Session 1 was conducted during the week before beginning a residency, and session 2 at 6 months into a first-year surgical residency. The mean time of the end of nocturnal sleep and the timing of the temperature rhythm were both (P less than .01) approximately 2.3 h earlier in session 2 (vs. 1). The sleepiness rhythm and the overall mood score rhythm were also phase-advanced (P less than .05) in session 2. The mean value of mood around-the-clock was significantly worse due to increased anger, tension, confusion, depression, and fatigue in session 2. Vigilance, tested by simple reaction time, did not exhibit a 25-h rhythm and was worse in session 2 with an increase (P less than .05) in mean response latency less than 1 s and an increase (P less than .01) in lapse time (microsleep, greater than 1- s latency). The urinary cortisol rhythm exhibited a raised curve average value (mesor) in session 2 (vs. 1, P less than .05), but no difference was revealed in amplitude or acrophase. Urinary excretion of Na+, K+, and Cl- did not differ between sessions, though the Na+/K+ ratio peaked earlier in session 2 (P less than .05). The urinary 6-sulfatoxymelatonin rhythm did not differ in timing, amplitude, or mesor between sessions. A residency training schedule can be associated with altered timing in rhythms of sleep, sleepiness, temperature, and mood and with deterioration of mood and performance without detectable alteration of the endogenous melatonin pattern as exhibited by the excretion rate of the principal urinary metabolite.
J Pineal Res 1988
PMID:Alterations of temperature, sleepiness, mood, and performance in residents are not associated with changes in sulfatoxymelatonin excretion. 322 34

A hind-leg subcutaneous saline injection into rats at night elicits a decrease in N-acetyltransferase (NAT) activity and melatonin content of the pineal gland. The decrement in pineal melatonin production after saline injection is prevented by adrenalectomy. The present studies were undertaken to determine what factor(s) from the adrenal gland cause(s) the drop in pineal melatonin production after saline injection at night. In the first study, groups of intact and adrenal-demedullated male rats were given a saline injection at 23.10 h (3 h, 10 min after lights off) and their pineals were collected 15 or 30 min later. Pineal NAT activity was depressed in both intact and adrenal-demedullated rats at 15 min postinjection as compared to their respective control animals. Pineal melatonin levels exhibited a drop in intact animals at 15 min and in adrenal-demedullated rats at 30 min. In a second study, hypophysectomy was found to prevent the drop in nocturnal pineal NAT activity and melatonin levels normally associated with a hind leg injection of saline. Finally, in a third experiment, groups of hypophysectomized rats were injected i.p. with corticosterone at 23.10 h and killed 10, 25 or 40 min postinjection. Corticosterone injection in hypophysectomized rats produced a response similar to that caused by saline injection in intact animals: NAT activity was depressed at 10 min and melatonin content was lowered at 25 min. These results suggest that the adrenal-mediated depression in melatonin synthesis after saline injection at night in rats may be elicited by an adrenal cortical hormone (corticosterone) and apparently does not involve the release of factors from the adrenal medulla.
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PMID:The depression in rat pineal melatonin production after saline injection at night may be elicited by corticosterone. 340 9

Female Syrian hamsters were kept in a light (14:10 h light:dark cycle, lights on 0600 h)- and temperature (22 or 30 degrees C)-controlled room; some groups were treated with an afternoon s.c. injection of melatonin (6.25, 12.5, or 25 micrograms/day) for 11 or 14 weeks. The melatonin-induced suppression of the reproductive system in hamsters maintained at 22 degrees C (as measured by vaginal cycles, uterine weights, ovarian histology, and plasma and pituitary prolactin levels) was delayed if hamsters were kept at 30 degrees C. The dose-related depression of thyroxine (T4) after melatonin injections for 14 weeks in 22 degrees C was not seen at 30 degrees C. Rather, the depression of plasma T4 and triiodothyronine (T3) seen at the end of 11 or 14 weeks of exposure to 30 degrees C without melatonin injections (vs. control levels at 22 degrees C) was offset by melatonin injections, raising T4 and T3 particularly at the lower doses. In contrast, there was no consistent effect of higher temperature alone on reproductive variables. The interactive effects of temperature and melatonin on the reproductive and thyroidal systems in female hamsters are apparently complex and probably provide a fine-tuning mechanism for the environmental control of endocrine physiology.
J Pineal Res 1988
PMID:Elevated environmental temperature alters the responses of the reproductive and thyroid axes of female Syrian hamsters to afternoon melatonin injections. 340


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