bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultracytochemical Localization of Calcium in the Superficial Pineal Gland of the Mongolian Gerbil
Authors: Krstić Radivoj 
Published: February 2007

In order to demonstrate fine localization of Ca2+ in the superficial pineal gland of Meriones unguiculatus, the pyroantimonate technique was employed. Control experiments were performed with EGTA and analysis of obtained reaction product using an energy‐dispersive x‐ray microanalysis.Precipitates of calcium antimonate were formed almost exclusively in swollen clear pinealocytes, in and along their cell membranes, over their nuclei, in mitochondria, the Golgi apparatus, endoplasmic and integrade reticulums. acervuli, in vesicles surrounding synaptic bars, cytoplasmic matrix, and flocculent extracellular material. It has been concluded that the swollen pinealocytes represent a degenerative cell form probably occurring by impairment of plasmalemmal Ca2+‐ATPase's ability to eliminate Ca2+ ion from the cell, with consecutive increase of calcium in the cytoplasmic matrix, followed by increase of intramitochondrial Ca2+ concentration, gradual arrest of mitochondrial function, depolymerization of cytoskeletal microtubuli, loss of the cell form, and cell death. Decrease of function of pinealocyte plasmalemma seems to be related to aging.
Pineal, Retinal, Serum Melatonin, and N‐Acetylserotonin Rhythms in Chicks on Reversing Light Regimen Eye Covering
Authors: Nir Isaac , Allen Andrée E. , Pang Shiu F. 
Published: February 2007

After reversing a 12:12‐h light‐dark regimen of environmental lighting, pineal retinal melatonin levels of white leghorn chicks recorded at the first mid‐darkness were greatly enhanced reached maximum levels after three more days; those recorded during the light periods indicate gradual decline but were far from the nadir of the original light period, even at the end of the experiment.The first mid‐darkness serum melatonin levels recorded after photoperiod reversal were not much different from their original mid‐light values. However, on continuing with the reversed regimen, the next mid‐darkness levels were sharply increased, maximum levels were reached after a further 2 days. Under the same experimental conditions light had much more drastic effects, 6 h on the reversed regimen were sufficient to bring down completely the high value of the original mid‐darkness period to the level of the starting mid‐light nadir.Retinal N‐acetylserotonin (NAS) measured simultaneously had a pattern similar to that of melatonin, but the pineal NAS rhythm did invert completely, albeit gradually.Eye covering did not prevent inversion of pineal serum melatonin rhythms, which were identical in eye‐covered sighted control chicks on the reversed regimen of light. However, retinal melatonin values of the light periods were significantly less depressed in eye‐covered than in sighted control chicks. Moreover, eye covering completely prevented the retinal NAS depression under light but did not affect pineal NAS. During darkness retinal pineal NAS elevation was sluggish in the eye‐covered chicks.
The effect of pinealectomy and autonomic denervation on crypt cell proliferation in the rat small intestine
Authors: Callaghan B.D. 
Published: February 2007

Abstract: Previously it has been found that pinealectomy in rats was associated with increased small bowel crypt cell proliferation. The hypothalamus is thought to play a role in the neural control of crypt cell proliferation and the pineal gland is known to be functionally connected with this component of the autonomic nervous system. Consequently, the effect on crypt cell mitotic rate of pinealectomy with autonomic ienervation of the rat small bowel (local sympathectomy and truncal vagotomy) was observed to determine the possible importance of the autonomic nervous system in the mediation of the effects of pinealectomy on the crypts.It was found that interruption of either the vagal or sympathetic nerve supply to the small intestine both significantly decreased the usual hyperproliferative effect on the crypt cells observed after pinealectomy. It is suggested that the overall effect of the pineal gland is to suppress the crypt cell proliferation rate and that this effect is mediated, at least to some extent, by (1) the direct connections between the pineal gland and the hypothalamus, (2) the connections between the hypothalamus and the vagal and sympathetic innervation of the gut, and (3) the influence of the autonomic innervation on the activity of the enteric plexuses in relationship to the crypts. The pineal may have a role in modulating the local control mechanism of crypt cell proliferation. Its exact role in the control of crypt cell proliferation has not yet been defined.
Effects of febrile and epileptic convulsions on daily variations in plasma melatonin concentration in children
Authors: Molina‐Carballo A. , Acuña‐Castroviejo D. , Rodriguez‐Cabezas T. , Muñoz‐Hoyos A. 
Published: February 2007

Molina‐Carballo A, Acuna‐Castroviejo D, Rodriguez‐Cabezas T, Munoz‐Hoyos A. Effects of febrile and epileptic convulsions on daily variations in plasma melatonin concentration in children. J. Pineal Res. 1994: 16: 1–9.AbstractPlasma melatonin was measured in 118 infants and children (39 controls, 28 with epileptic convulsions, and 51 with febrile convulsions). The control group displayed a typical circadian rhythm, with melatonin peaking between 0200 and 0400. This normal daily variation significantly changed in the epileptic group, which showed a characteristic phase‐advance, with the nocturnal melatonin peak appearing between 2400 and 0200. Febrile convulsions were associated with the disappearance of the normal circadian rhythm of melatonin, which was replaced by melatonin bursts throughout the light: dark cycle. In both febrile and epileptic children, melatonin levels were significantly increased in comparison with normal children.
Detection and quantification of melatonin in a dinoflagellate, Gonyaulax polyedra: Solutions to the problem of methoxyindole destruction in non‐vertebrate material
Authors: Poeggeler Burkhard , Hardeland Rüdiger 
Published: February 2007

Poeggeler B, Hardeland R. Detection and quantification of melatonin in a dinoflagellate, Gonyaulax polyedra: Solutions to the problem of methoxyindole destruction in non‐vertebrate material. J. Pineal Res. 1994: 17: 1–10.AbstractPreservative procedures are described for the extraction and quantification of melatonin in cell material from the dinoflagellate Gonyaulax polyedra, an organism in which this indoleamine is rapidly degraded due to interaction with free oxygen radicals and photooxida‐tion. Cells were shock‐frozen in liquid nitrogen and pulverized. Various extraction methods were applied to the powder, and rates of recovery were compared. For the determination of melatonin by high performance liquid chromatography (HPLC), extractions with acetone or perchloric acid were more suitable than the use of other solvents. For purposes of radioimmunoassay (RIA), extraction with acetone gave the best results. Several other inorganic solvents, which are often applied in melatonin research, such as chloroform, dichloromethane, and diethyl ether, led to considerable losses of the indoleamine. The procedures developed for HPLC with either electrochemical or fluorescence detection also allow the quantification of other indolic compounds, in particular, tryptophan and 5‐methoxytryptamine. The methods described may be of value in the further search for melatonin and related indoleamines in non‐vertebrate material, especially, from unicells, multicellular plants, and invertebrates.
Effect of two weeks of continuous light on the development of the circadian melatonin rhythm in newborn lambs
Authors: Fielke S. L. , Young I. R. , Walker D. W. , McMillen I. C. 
Published: February 2007

Fielke SI, Young IR, Walker DW, McMillen IC. Effect of two weeks of continuous light on the development of the circadian melatonin rhythm in newborn lambs. J. Pineal Res. 1994; 17: 118–122AbstractWe have investigated the effect of exposure of newborn lambs to continuous light during the first 2 weeks after birth on the subsequent development of the phase and amplitude of the plasma melatonin rhythm during the next 8 weeks. During the first 2 weeks after birth, the mean plasma melatonin concentrations were significantly lower (P < 0. 001) in lambs exposed to continuous light (58 ± 15 pmol/1, n = 7) than in lambs exposed to LD 12: 12 (i. e., “normal” lighting: 189 ± 38 pmol/1, n = 9). Between 3 and 4 weeks of age, plasma melatonin concentrations during the daily light and dark periods were also significantly lower in the lambs exposed to continuous light during the first 2 weeks after birth. There was no effect of time of day on plasma melatonin in either group of lambs during the first 2 weeks after birth but between 3 and 10 weeks of age there was a significant (P < 0. 001) effect of light and dark and time of day on plasma melatonin concentrations which was the same in both groups of lambs. Plasma melatonin concentrations were higher in the dark period than in the light period and between 2100 and 0700 than between 0900 and 1700 at all ages after week 2. We have therefore demonstrated that exposure of the lamb to 2 weeks of continuous light after birth results in a suppression of melatonin secretion that extends beyond the end of the exposure to continuous light.
Modulation of melatonin secretion by acetyl‐L‐carnitine in adult and old rats
Authors: Esposti D. , Mariani M. , Demartini G. , Lucini V. , Fraschini F. , Mancia M. 
Published: February 2007

Esposti D, Mariani M, Demartini G, Lucini V, Fraschini F, Mancia M. Modulation of melatonin secretion by acetyl‐L‐carnitine in adult and old rats. J. Pineal Res. 1994; 17: 132–136.Abstract; Modification of melatonin synthesis and release by acetyl‐L‐carnitine (ALC) was studied in adult (2 month old) and old (24‐month‐old) male Sprague Dawley rats. When ALC was injected at 1500 into adult rats at doses of 10, 30, or 90 mg/kg, there was a remarkable increase in their pineal and serum melatonin 1 hr later. However, using the same experimental protocol acute ALC administration in old rats did not modify pineal and serum melatonin levels. ALC administered in the same dose range induced a significant increase in pineal and serum melatonin in adult rats treated at 0100 h following exposure of 30 min to bright, white light to suppress endogenous melatonin. In the same conditions, in old rats, only the higher dose (90 mg/kg) caused any noteworthy increase in melatonin pineal content while lower doses were ineffective both on serum and pineal melatonin levels. It is known that ALC affects fatty acid transport in the cells, modulates Co A, modifies neuronal transmission and reduces lipofuscin accumulation which is related to lipid per oxidation. The action of ALC on melatonin synthesis could be the result of a modulation of the neuronal transmission related to circadian pineal endocrine activity. Moreover, since both ALC and melatonin exert remarkable scavenger activity, it is possible to suppose that ALC effects in reversing certain aging processing may be due to its ability to promote melatonin production.
Melatonin enhances Cortisol levels in aged women: Reversible by estrogens
Authors: Cagnacci A. , Soldani R. , Yen S.S.C. 
Published: February 2007

Cagnacci A, Soldani R, Yen SSC. Melatonin enhances Cortisol levels in aged women: Reversible by estrogens. J. Pineal Res. 1997; 22:81–85. © Munksgaard, CopenhagenAbstractThe administration of melatonin increases Cortisol levels in postmenopausal women. Aging and hypoestrogenism are believed to impair the regulation of the hypothalamo‐pituitary‐adrenal axis and may participate in the determination of this altered response. In this study the implications of hypoestrogenism were tested. Seven postmenopausal women were studied. At 08.00 hr for 2 consecutive days, each woman received randomly and in a double blind fashion a pill of placebo or melatonin (100 mg). Serum melatonin and Cortisol levels were evaluated at 20 min intervals, for 48 hr. Measurements were performed in the same subjects both during no estrogen supplementation and at least two cycles of conjugated estrogens administration (0.625 mg/day). During estrogen supplementation, postmenopausal women showed slightly lower Cortisol levels at lunch and early night (20.00–01.00 hr). The onset of the nocturnal melatonin rise was not modified, but that of Cortisol was delayed of about 60 min (P<0.02). The administration of melatonin elicited a marked increase in daytime Cortisol levels in postmenopausal women (P<0.02), but this stimulus completely disappeared during estrogen administration. Mean nighttime (20.00–08.00 hr) Cortisol levels were not modified by daytime administration of melatonin. The present data reveal that in aged postmenopausal women, reversal of hypoestrogenism, resulting from supplemental estrogens, may improve the regulation of the hypothalamo‐pituitary‐adrenal axis.
Circadian rhythm in experimental granulomatous inflammation is modulated by melatonin
Authors: Lopes Cristiane , DeLyra Jorge Lacerda , Markus Regina Pekelmann , Mariano Mario 
Published: February 2007

Lopes C, deLyra JL, Markus RP, Mariano M. Circadian rhythm in experimental granulomatous inflammation is modulated by melatonin. J. Pineal Res. 1997; 23:72–78. © Munksgaard, CopenhagenAbstractBiological rhythms are detected in a variety of physiological and pathological conditions in man and animals, such as rheumatoid arthritis and asthma. Here we describe a circadian rhythm in experimental infectious and non‐infectious granuloma. After 30 days of BCG (Bacillus Calmette‐Guerin) or nystatin inoculation in the left hind foot of C57B1/6 mice, there is an oscillation with a period of approximately 24 hr in the variation of paw thickness, indicating a circadian rhythm. The acrophase occurred during the light phase, between 9:00 and 13:00 hr, while the nadir occurred in the dark phase, between 21:00 and 01:00 hr. The vascular permeability around the granulomatous lesions was higher at 12:00 hr than at 24:00 hr. This is in agreement with the observation that the thickness of a paw with granulomatous lesion is larger during the light phase. This rhythmic variation was eliminated by either pinealectomy or superior cervical ganglionectomy, which greatly reduce melatonin levels in the blood. Nocturnal replacement of melatonin in pinealectomized mice led to the re‐establishment of the circadian rhythm. Thus, the rhythm of the granulomatous lesion is due to the rhythmic melatonin release by the pineal gland. This approach opens new questions regarding the modulation of chronic inflammation in inflammatory diseases that present rhythmic symptoms throughout the day.
The effect of pinealectomy on the crypts of defunctioned rat colon
Authors: Callaghan B.D. 
Published: February 2007

Callaghan B.D. The effect of pinealectomy on the crypts of defunctioned rat colon. J. Pineal Res. 1997; 23:117–122. © Munksgaard, CopenhagenAbstractPreviously it has been found that 6 months after pinealectomy hyperplasia occurred in the crypt cells of the rat small bowel and colon. It is also known that defunctioning a loop of colon, using a colostomy, results in crypt cell hypoplasia, emphasizing the prime importance of luminal factors in the control of crypt cell proliferation. To determine if the effects of pinealectomy on the colon could be modified by the absence of colonic luminal contents, the crypt cell kinetic effects of combined pinealectomy and defunctioning of a colonic loop by colostomy for 6 months were examined by using a stathmokinetic technique. It was found that the hypoproliferative effect of defunctioning a loop of colon was largely but not completely overridden by the hyperproliferative effect of pinealectomy. However, previously it has been found that in the rat small bowel, the hypoproliferative effects of defunctioning a loop were completely overridden by the effect of pinealectomy. This and other evidence suggests that the role of the pineal in the control of crypt cell proliferation in the colon may possibly be different from its role in the small bowel. There is other evidence of possible involvement of the pineal in carcinoma of the colon and it is possible that its role in the colon may be to prevent excessive mitotic activity, which is known to be present in the early stages of carcinoma. The Pineal gland may have a role in modulating the usual mechanisms of crypt cell mitotic control.
Supplemental melatonin increases clonal lifespan in the protozoan Paramecium tetraurelia
Authors: Thomas John N. , Smith‐Sonneborn Joan 
Published: February 2007

Thomas JN, Smith‐Sonneborn J. Supplemental melatonin increases clonal lifespan in the protozoan Paramecium tetraurelia. J. Pineal Res. 1997; 23:123–130. © Munksgaard, CopenhagenAbstractThe hypothesis that melatonin supplementation can increase the lifespan of a single‐celled organism was tested by the administration of melatonin to the ciliated protozoan Paramecium tetraurelia. Melatonin supplementation in dim red light at a dose of 0.043 mM (10 mg/L) of nutrient media (bacterized Cerophyl) per day, followed by incubation for 23 hr in darkness, increased the mean clonal lifespan of Paramecium tetraurelia in days by percentages ranging from 20.8% (P < 0.01, two‐tailed t‐test) to 24.2% (P < 0.01, ANOVA) over controls. Maximum clonal lifespan in days was also increased in melatonin‐supplemented cells, from 14.8% to 24.0% over controls. Mean clonal lifespan in fissions was not significantly greater in melatonin‐supplemented cells, with values ranging from 6.0% to 15.5% over controls. Maximum clonal lifespan in fissions did not differ appreciably, with values ranging from 1.0% to 9.1 % over controls, except in the case of cells selected for rapid division rates, in which melatonin‐supplemented cells (393 fissions) lived 20.9% longer than controls (325 fissions) in terms of cumulative cell doublings during the clonal lifespan. The finding that melatonin supplementation increased clonal lifespan in Paramecium tetraurelia, an aerobic, single‐celled organism, suggests that the mechanism of melatonin's longevity‐promoting effects may be intracellular.
Involvement of protein kinase A in the subjective nocturnal rise of melatonin release by chick pineal cells in constant darkness
Authors: Nakahara Keiko , Murakami Noboru , Nasu Tetsuo , Kuroda Haruto , Murakami Takayuki 
Published: February 2007

Nakahara K, Murakami N, Nasu T, Kuroda H, Murakami T. Involvement of protein kinase A in the subjective nocturnal rise of melatonin release by chick pineal cells in constant darkness. J. Pineal Res. 1997; 23:221–229. © Munksgaard, CopenhagenAbstractMelatonin release by chick cultured pineal cells increases during the dark periods and decreases during the light periods under light‐dark cycles, and this rhythmic secretion is maintained under constant conditions with a period of almost 24 hr. The mechanisms by which the circadian oscillator drives the melatonin rhythm under constant conditions have not been elucidated enough. We examined the possibility that cyclic AMP‐dependent protein kinase A is involved in the subjective nocturnal increase in melatonin release by chick pineal cells cultured under constant darkness. The subjective nocturnal increase of melatonin release was suppressed dose dependently by H8 (protein kinase inhibitor) and H89 (specific protein kinase A inhibitor), but not by calphostin C (specific protein kinase C inhibitor) in static cell cultures. In a cell perfusion experiment, 9 hr pulses of H8 and H89 starting at ZT 9 (CT 11.2) hr suppressed the subjective nocturnal increase in melatonin rhythm in dose‐dependent manner without causing a phase shift. An intracellular Ca2+ chelator, O,O'‐bis(2‐aminophenoxy)ethyleneglycol‐N,N,N',N'‐tetraacetic acid tetraacetoxymethyl ester (BAPTA‐AM), and extracellular Ca2+ chelators, O,O'‐bis(2‐aminophenoxy)ethyleneglycol‐N,N,N',N'‐tetraacetic acid tetrapotassium salt hydrate (BAPTA) and ethyleneglycol‐bis(β‐aminoethyl ether)‐N,N,N',N'‐tetraacetic acid (EGTA), suppressed both the subjective nocturnal increases in melatonin release and cAMP levels dose dependently. This direct evidence strongly supports the hypothesis that cAMP‐dependent protein kinase A may be involved in the subjective nocturnal increase in melatonin release by chick pineal cells and that intracellular Ca2+ plays an important role in pineal adenylate cyclase activation.
Melatonin controls superoxide anion level: Modulation of superoxide dismutase activity in ring dove heterophils
Authors: Rodríguez A. B. , Nogales G. , Ortega E. , Barriga C. 
Published: February 2007

Rodríguez AB, Nogales G, Ortega E, Barriga C. Melatonin controls superoxide anion level: Modulation of superoxide dismutase activity in ring dove heterophils. J. Pineal Res. 1998; 24:9–14. © Munksgaard, CopenhagenAbstractThe pineal gland and the immune system in mammals and birds are functionally connected, with some recent findings showing that melatonin, the major secretory product of the pineal gland in vertebrates, is a free‐radical scavenger and general antioxidant. In birds, heterophils, with their ability to ingest and kill different antigens, play a central role in the host defense mechanism. This in vitro study investigated the possible antioxidant action of melatonin in heterophils isolated from adult male and female ring dove)Streptopelia risoria). The superoxide anion levels (O2−) and the superoxide dismutase (SOD) activity were evaluated as indicators of the metabolic burst of heterophils after ingestion of inert particles (latex beads) at the basal time (0 min) and 15, 30,45, and 60 min of incubation with 100 μM melatonin. The heterophil O2−levels, measured by the nitroblue tetrazolium reduction test, were lower after incubation in the presence of melatonin at all the times studied, a time‐dependent effect. Latex beads produced a significant increase in SOD activity, whereas there was a significant decrease in the presence of melatonin. In addition, when heterophils were incubated in the presence of both latex beads and melatonin, the indole appeared to annul the enhancement of SOD activity (U‐525nm) produced by latex beads. In conclusion, our findings show that the neurohormone melatonin could be a useful antioxidant.