Hypothalamic and neurohypophysial vasopressin and oxytocin in melatonin-treated pinealectomized male rats.
TL;DR: Following pineal removal, melatonin did not augment the pinealectomy‐induced decrease of vasopressin and oxytocin in the neurohypophysis; the hypothalamic storage of both neurohormones was even higher when compared with vehicle‐treated animals.
Abstract: The effect of melatonin on hypothalamic and neurohypophysial vasopressin and oxytocin was investigated in normal and pinealectomized rats. Pinealectomy was followed by a decrease of both vasopressin and oxytocin content in the hypothalamus and neurohypophysis. In unpinealectomized rats, melatonin decreased vasopressin and oxytocin storage in the hypothalamo-neurohypophysial system. Following pineal removal, melatonin did not augment the pinealectomy-induced decrease of vasopressin and oxytocin in the neurohypophysis; the hypothalamic storage of both neurohormones was even higher when compared with vehicle-treated animals.
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TL;DR: Results demonstrate that melatonin affects the neurosecretory function of the hypothalamo-neurohypophysial complex in vivo possibly via mechanisms involving cholinergic transmission and/or prostaglandin biosynthesis.
46 citations
TL;DR: It is demonstrated that afternoon injections of melatonin can alter renal function, which may involve direct ( i.e., on ADH secretion and/or thirst mechanisms) or indirect (i.e, behavioral) effects.
Abstract: The pineal indoleamine, melatonin, has been shown to influence many physiological systems within the mammalian body. Few studies, however, have examined the influence of melatonin on renal function. This study investigated the effects of melatonin on water metabolism and renal function. Young adult male Syrian hamsters were maintained on a long photoperiod (LD 14:10) in metabolic cages. The animals received daily (1700) injections of either control vehicle or 25 micrograms of melatonin for 85 consecutive days. Melatonin administration resulted in significant increases in water consumption and urine production. Water budgets were also significantly influenced by melatonin, as were urinary osmolality, urinary sodium, and potassium concentrations, but urinary calcium concentrations were essentially unaltered. When excretion rates for sodium, potassium, and calcium were calculated, no differences were observed between the vehicle control and melatonin-treated groups. Injections of melatonin also significantly decreased plasma antidiuretic hormone (ADH). These results demonstrate that afternoon injections of melatonin can alter renal function, which may involve direct (i.e., on ADH secretion and/or thirst mechanisms) or indirect (i.e., behavioral) effects.
39 citations
TL;DR: It is concluded that daily perphenazine treatment hastened the growth of follicles and subsequent ovulation while bromocriptine treatment appeared to delay the growthof preovulatory size follicles without affecting the time of ovulation.
32 citations
TL;DR: Exogenous MEL seems to inhibit suckling-induced OT as well as PRL secretion when applied at doses regarded to be in the range of the physiological level; when applied in higher doses, it was shown not to influence the release of OT following physiological stimulation such as suckling.
30 citations
TL;DR: The effect of melatonin as well as pinealectomy on the basal and K+‐evoked release of vasopressin and oxytocin from the neurointermediate lobes in vitro was determined and did not affect the Oxytocin release either under basal conditions or during depolarization due to excess potassium.
Abstract: The effect of melatonin as well as pinealectomy on the basal and K(+)-evoked release of vasopressin and oxytocin from the neurointermediate lobes in vitro was determined. Pineal removal resulted in a diminution of vasopressin and oxytocin release from the neurointermediate lobes in vitro. Melatonin (10(-3) or 10(-6) M/l) increased vasopressin and oxytocin release from neurointermediate lobes of sham-operated rats. Nevertheless, when pinealectomized rats served as donors of the neurointermediate lobes, melatonin (10(-3) or 10(-6) M/l) increased vasopressin release under basal conditions. For the same tissue, melatonin did not affect the oxytocin release either under basal conditions or during depolarization due to excess potassium. When 10(-7) M/l melatonin was used, no changes in either vasopressin or oxytocin release were observed in vitro.
27 citations
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TL;DR: In this article, a test of the hypothesis that the samples are from the same population may be made by ranking the observations from from 1 to Σn i (giving each observation in a group of ties the mean of the ranks tied for), finding the C sums of ranks, and computing a statistic H. Under the stated hypothesis, H is distributed approximately as χ2(C − 1), unless the samples were too small, in which case special approximations or exact tables are provided.
Abstract: Given C samples, with n i observations in the ith sample, a test of the hypothesis that the samples are from the same population may be made by ranking the observations from from 1 to Σn i (giving each observation in a group of ties the mean of the ranks tied for), finding the C sums of ranks, and computing a statistic H. Under the stated hypothesis, H is distributed approximately as χ2(C – 1), unless the samples are too small, in which case special approximations or exact tables are provided. One of the most important applications of the test is in detecting differences among the population means.* * Based in part on research supported by the Office of Naval Research at the Statistical Research Center, University of Chicago.
9,365 citations
TL;DR: An N-acetylserotonin/melatonin radioimmunoassay (NAS/Mel RIA) and a Mel RIA were developed to measure NAS and Mel contents in tissues of rats and chickens and Mel levels in chicken serum were determined using these RIAs.
Abstract: An N-acetylserotonin/melatonin radioimmunoassay (NAS/Mel RIA) and a Mel RIA were developed to measure NAS and Mel contents in tissues of rats and chickens. Anti-NAS and anti-Mel sera were produced by immunization of rabbits with NAS-M-bovine serum albumin (BSA) and Mel-M-BSA, respectively. Anti-NAS serum used in the NAS/Mel RIA reacts equally well with NAS and Mel, while anti-Mel serum used in the Mel/RIA reacts specifically with Mel. The NAS and Mel levels in the pineal and Harderian gland, the retina and the brain of rats and chickens and Mel levels in chicken serum were determined using these RIAs. Levels of NAS and Mel in the rat pineal demonstrated diurnal rhythms with high levels during the dark period and low levels during the light period. The indole levels determined in this study correlate well with those obtained by other methods.
225 citations
"Hypothalamic and neurohypophysial v..." refers background in this paper
...Melatonin itself has been identified within the pineal, retina, harderian gland, serum, nervous tissue, and digestive system of mammals and birds [Pang et al., 1977; Brown et al., 1985; Bubenik, 1980; Pang and Allen, 19861....
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TL;DR: High affinity binding of melatonin in crude membrane preparations of bovine brain was examined by a rapid filtration procedure through Whatman GFB paper and melatonin binding was maximal in the MBH; indole binding in occipital and cerebellar cortexes was 73% and 34% that of MBH.
Abstract: High affinity binding of melatonin in crude membrane preparations of bovine brain was examined by a rapid filtration procedure through Whatman GFB paper. Melatonin binding to medial basal hypothalamic (MBH) membranes attained its maximum at the first, third, and fifth hours of incubation at. 37,18, and 0 C, respectively. Specific binding was linear up to 3 mg membrane protein, was thermolabile, and decreased after incubation with trypsin; it was also pH dependent, the maximum being observed at pH 7.4. Melatonin binding was affected by a variety of ionic manipulations; it was inhibited 55% and 62% after addition of 10 mM KC1 and 120 mM NaCl, respectively, and it was increased 40% and 50% after the addition of 4 or 6 mM CaCl2. Melatonin binding was increased 25% by 1.25 mM MgCl2, whereas it was depressed at higher concentrations. Among the various brain regions studied, melatonin binding was maximal in the MBH; indole binding in occipital and cerebellar cortexes was 73% and 34% that of MBH. Subcellular frac...
220 citations
201 citations
"Hypothalamic and neurohypophysial v..." refers background in this paper
...These neurotransmitters are all known to be involved in the mechanisms of release of neurohypophysial hormones [Sklar and Schrier, 1983; Guzek, 19841....
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TL;DR: A specific practical radioimmunoassay suited to determinations of melatonin in both tissues and body fluids is described, and its occurrence in the plasma of man, sheep, rat and chicken was confirmed.
Abstract: A specific practical radioimmunoassay suited to determinations of melatonin in both tissues and body fluids is described. The rabbit antibody employed was raised to an antigen formed by condensation between N-acetylserotonin and the Mannich adduct of bovine serum albumin and formaldehyde. Substitution was shown by protonmagnetic resonance spectroscopy to occur exclusively at die 4 position of the indole nucleus. The antibody reacted with a variety of N-acetylated indoles, and absolute specificity was dependent upon the extraction procedure and column (Lipidex 5000) chromatography. In addition to the usual reliability criteria, the validity of the assay was checked by gas chromatography- mass spectrometry using [2H3]melatonin as an internal standard, the preparation of which is described. The occurrence of melatonin in the plasma of man, sheep, rat and chicken was confirmed, and its presence in the plasma of the pig (22–76 pg/ml), donkey (24–128 pg/ml), cow (20–320 pg/ml), camel (29–221 pg/ml) and a scinci...
198 citations