Estimation of the methylating capacity of the pineal gland. With special reference to indole metabolism

In order to obtain more information on the methylating capacity of the pineal gland, a method determining the formation of different 5-methoxyindoles in the pineal gland was developed. The method depends on measuring the incorporation of labelled methyl groups into the various hydroxyindoles present in the pineal gland, after incorporation of pineal tissue with labelled S-adenosyl methionine. Hydroxyindoles were not added to the incubation medium. After incubation thin-layer chromatography was performed with pineal tissue together with the incubation medium; the spots were scraped and counted.     

Estimation of the methylating capacity in the pineal gland of the rat with special reference to the methylation of N-acetylserotonin and 5-hydroxytryptophol separately

Summary In the present paper, an extension is presented of an earlier described method, by which the methylating capacity of the pineal gland can be determined. Supplementary to the earlier method, the synthesis of melatonin and 5-methoxytryptophol can now be qualified and quantified separately.The authors wish to express their gratitude to Prof. Dr J.C. van de Kamer and Dr F.C.G. van de Veerdonk for their stimulating interest in these studies.     

Scanning electron microscope observations of the canaliculi in the rat pineal gland

Summary The scanning electron microscope has shown rich ramifications of the parenchymal canaliculi forming a three-dimensional network of anastomosing intercellular spaces in the rat pineal gland. Every pineal cell seems to be in contact with this channel system. An abundance of cellular processes can be found within the canaliculi which may play an important role in the histophysiology of the pineal body. Dedicated to Prof. Dr. med.W. Bargmann on the occasion of his 70th birthday.     

Variations of the labelling index in vitro of rat mammary gland in pregnancy and early lactation

Summary The labelling index of rat mammary gland during oestrus, pregnancy and early lactation was studied in vitro. The implications concerning the existence of a critical cell division are discussed.The authors wish to thank G. Th. J. Rödiger for his technical assistance and Prof. Dr. C. van der Meer for his professional advice.     

Autoradiographic studies on RNA synthesis and transport in the Salivary gland ofLygaeus sp. (Hemiptera-Lygaeidae)

Summary Autoradiographic studies using³H-uridine in the salivary gland of adultLygaeus sp. were carried out. The gland cell nuclei, particularly the multiple nucleoli, are the sites of incorporation of the label exhibiting RNA synthesis. The labelled molecules (RNA) are transported to the cell cytoplasm and then into the gland lumen in which no turnover of the radioactivity is observed.I am grateful to my teacher, Prof. P. S. Ramamurty, School of Life Sciences, University of Hyderabad, for his constant inspiration. Grateful acknowledgement is made to Prof. J. P. Thapliyal, Dept of Zoology, B. H. U. for encouragement and to Dr Om Prakash, Dept of Biochemistry, B. H. U. for his valuable criticism.     

Evidence for in vitro release of neurophysin by the rat pineal gland

Summary Cultured pineal ependymal cells from rat fetuses release into their incubation media immunoreactive neurophysin. The presence of neurophysin was assessed by radioimmunoassay. The culture medium was found to contain 440 pg neurophysin per mg protein.     

DNA synthesis in the pituitary gland of the rat: Effect of sulpiride and clomiphene

Summary Sulpiride administration to rats releases prolactin and increases DNA replication in the anterior pituitary gland. Clomiphene prevents the stimulation of DNA synthesis produced by sulpiride, but does not affect prolactin release from the gland. These findings suggest that the intracellular prolactin content of the anterior pituitary gland plays a role in the regulation of DNA synthesis through a mechanism mediated by oestrogens.This work was supported by PLAMIRH 99.178.1.78, by the Consejo Nacional de Investigaciones Científicas y Técnicas and by the Comisión Nacional de Energía Atómica (Argentina). We are grateful to Dr P. Scacchi for performing the radioimmunoassay and to Prof. C. J. Gómez for the opportunity to perform this work.     

Autoradiographic studies on RNA synthesis and transport in the salivary gland of Lygaeus sp. (Hemiptera-Lygaeidae)

Autoradiographic studies using 3H-uridine in the salivary gland of adult Lygaeus sp. were carried out. The gland cell nuclei, particularly the multiple nucleoli, are the sites of incorporation of the label exhibiting RNA synthesis. The labelled molecules (RNA) are transported to the cell cytoplasm and then into the gland lumen in which no turnover of the radioactivity is observed.     

Pineal function cannot prevent the occurrence of castration cells in male rats

The relationship between the pineal gland and the pituitary gland was investigated in male rats. The results indicate that the hypothalamo-adenohypophysial-gonadal axis is affected by the pineal gland, but the appearance of castration cells following gonad ablation may be only slightly modified by alterations in pineal gland function.     

Pineal function cannot prevent the occurrence of castration cells in male rats

Summary The relationship between the pineal gland and the pituitary gland was investigated in male rats. The results indicate that the hypothalamo-adenohypophysial-gonadal axis is affected by the pineal gland, but the appearance of castration cells following gonal ablation may be only slightly modified by alterations in pineal gland function.     

Leucocyte invasion of the vaginal epithelium in the absence of bacteria in mice

Summary Influx of leucocytes in the vagina at metoestrus occurs in germfree mice and also in sterile isotransplants of vaginal tissue in conventional mice. In contrast to the situation in rats, bacteria thus do not seem to be required for the production of postovulatory leucotactic stimuli in the vagina.Acknowledgments. Data with germfree mice could be obtained through the generous cooperation of Prof. Dr F. Wensinck and Dr M. P. Hazenberg (Dept. Medical Microbiology, Erasmus University), C. Lekkerkerker and J. ten Veen (TNO, Zeist, The Netherlands). The skillfull cooperation of Miss P. D. M. van der Vaart and Mrs A. Verschoor-Burggraaf is gratefully acknowledged.     

Cholesterol content and cholesterol esterifying activity of various organs in guinea pigs

Summary In various organs of the guinea pig, the total cholesterol content of an organ was significantly correlated with the percentage of esterified cholesterol present in this organ. Cholesterol esterifying capacity was shown in most organs, with highest activities in the adrenals, the spleen and the liver. The significant correlation found between the cholesteryl ester content of an organ and its acyl cholesterol acyltransferase activity suggests a possible role of this enzyme in determining the level of the total and esterified cholesterol in a tissue.This work was supported by a grant Crédit aux Chercheurs du Fonds National de la Recherche Scientifique of Belgium.Acknowledgments. I am indebted to Prof. C. Harvengt for his stimulating interest and helpful suggestions. I wish to thank Y. van Nieuwenhuyze and J. Costermans for their valuable laboratory assistance and Dr H. Baudon for pathological studies.     

Lesions in suprachiasmatic nuclei simulate effects of pinealectomy on prolactin release in ovariectomized and sulpiride-treated female rats

Summary Previous studies indicate that the pineal gland alters prolactin secretion, and it was suggested that at least part of the effect of the pineal hormone melatonin on prolactin release may be mediated by the hypothalamic structures. In this study, pinealectomy and lesions of the suprachiasmatic nuclei were found to alter serum levels of prolactin in the same direction, an effect that was counteracted by daily afternoon melatonin administration. Melatonin, but not other pineal indoles, also prevented sulpiride-induced prolactin secretion in pinealectomized or suprachiasmatic nuclei-lesioned and ovariectomized rats, which suggested that the pineal gland can modulate prolactin secretion by acting through a dopamine mechanism independent of hypothalamic suprachiasmatic structures.The authors thank Ms Karen Shashok for revising the English style. This work was supported in part by a grant GG85-0168 from the Comisión Asesora de Investigación Cientifica y Ténica. The NIAMDD, through the National Pituitary Agency, supplied the radioimmunoassay materials for prolactin determinations.     

Persistence of added retinoids in organ culture media during induction of mucous metaplasia and glandular morphogenesis in hamster cheek pouches

The retinoid concentration (determined colorimetrically) did not change significantly in retinyl acetate-supplemented (6 micrograms/ml) Eagle's Minimal Essential Medium containing 10% fetal calf serum when stored at -20 or 4 degrees C over 7 days. After the medium was incubated at 37 degrees C for 48 h, 37-49% of the retinoid remained, whether or not tissue (neonatal Syrian hamster cheek pouch) was present, and irrespective of explant age. The normal retinoid level in the tissue was approximately 0.25 micrograms per gram. Therefore, neonatal hamster cheek pouches, incubated in medium with the addition of 6 micrograms of retinyl acetate per ml of medium and undergoing mucous metaplasia and some mucous gland morphogenesis, were continually being exposed to retinoid levels which, though gradually decreasing, remained well above their normal physiological level.     

The influence of homologous plasma and fetal calf serum on human lymphocytic cortisol metabolism

Summary The influence of a) tissue culture medium (RPMI), b) homologous plasma (HP), and c) fetal calf serum (FCS) on lymphocytic cortisol metabolism was compared to that of phosphate buffered saline alone. RPMI was found to enhance the conversion rate 1.71 times, whereas HP and FCS enhanced it about 3.2 times. Raising the temperature of the HP and FCS to 100°C before incubation reduced the enhancing effect to the level of that obtained with RPMI.This work was supported by The Israel Cancer Research Fund N.Y. (George and Rose Blumenthal Research Fellowship for Hodgkins Disease). The authors are grateful to Dr Malchi and his staff from the Beilinson Hospital Blood Bank, for supplying us with buffy coats and to Mr Z. Klein for drawing the figure.     

Development of rhythmic melatonin synthesis in cultured pineal glands and pineal cells isolated from chick embryo

The chick pineal gland exhibits circadian rhythms in melatonin synthesis under in vivo and in vitro conditions. A daily rhythm of melatonin production was first detectable in pineal glands isolated from chick embryos at embryonic day 16 and incubated under a LD cycle. All pineal glands isolated from 17-day-old and older embryos were rhythmic while no gland isolated at embryonic day 14 and 15 exhibited a daily rhythm in melatonin synthesis. Melatonin production in static cultures of embryonic pineal cells was rhythmic over 48 h if the cells were kept under a LD cycle. When embryonic pineal cells were incubated in constant darkness the rhythm in melatonin production was damped within 48 h. These results suggest that chick pineal cells from embryonic day 16 onwards are photosensitive but that the endogenous component of the melatonin rhythm is not completely developed at that age. A soluble analogue of cAMP stimulated and norepinephrine inhibited melatonin synthesis in cultured embryonic pineal cells. These findings indicate that the stimulatory and inhibitory pathways controlling melatonin synthesis in the mature pineal gland are effective in pineal cells isolated from chick embryos at least 2 days before hatching.     

Narciclasine,an inhibitor of protein synthesis. Action onAllium cepa L. root meristems

Summary Shortening of nucleologenesis time in a synchronous cell population, labelled as binucleate, by a caffeine pulse and fall in frequency of prophases are related to narciclasine inhibition of protein synthesis inAllium cepa L. meristems.Acknowledgments. We gratefully acknowledge Dr D. Vázquez and Dr A. Jiménez, from the Instituto de Bioquímica de Macromoléculas, for calling our attention to this protein synthesis inhibitor and providing us samples both of narciclasine andNarcissus bulbs. We also greatly appreciate Dr B. Rodriguez and Dr F. M. Panizo of the Instituto de Química Orgánica (Departamento de Productos Naturales) for their valuable help in isolation and characterization of narciclasine, and for laboratory facilities. The work has been partially supported by the Comisión Asesora para la Investigación Científica (Spain). A.S. has a fellowship awarded by the Instituto de Cultura Hispánica, Spain.     

A study of irrigation fluids for neurosurgery on brain primary cell cultures

Summary Primary cell cultures from newborn rat brain hemispheres were exposed to different irrigation fluids used in neurosurgery. The cells died after incubation for 5 min with hydrogen peroxide, and the number of cells was drastically decreased after 10 sec of incubation. They shrank after incubation in Elliott's artificial cerebrospinal fluid for 3 h, but the viability as determined by trypan blue exclusion test was not affected. Physiological sodium chloride, Ringer's solution and the culture medium 199 with Hank's salt had no noticeable effect on the viability or morphology of the cells.Acknowledgments. This study was supported by grants from the Medical Faculty of Göteborg and from Statens Naturvetenskapliga Forskningsråd. We want to thank Dr Åke Sellström and Dr Hans-Arne Hansson for valuable discussions.     

On the mechanism of killing ofTrypanosoma cruzi by human polymorphonuclear leukocytes

Summary The temperature-dependence of some processes involved in the killing of sensitizedT. cruzi epimastigotes by human polymorphonuclear leukocytes (PMN) was determined. The rate of the reactions was related to the temperature of incubation according to the Arrhenius equation and the apparent energies of activation (Ea) were calculated. The Ea values separated these complex reactions into two groups: one with Ea of about 10 kcal/mol for the phagocytosis of the parasites and the release of lysosomal enzymes by PMN, and the other with Ea of about 22 kcal/mol for the cytotoxicity against sensitizedT. cruzi, the rate of oxygen consumption by PMN, and the lysis of the parasites with added hydrogen peroxide.This work was supported by research grants from CONICET and SUBCYT, Argentina, and UNDP/Word Bank/WHO Special Programme for Research and Training in Tropical Diseases. The author wish to thank Dr I. Reisin, Dr. A. Boveris and Dr M.M.E. de Bracco for their helpful discussion.     

Lesions in suprachiasmatic nuclei simulate effects of pinealectomy on prolactin release in ovariectomized and sulpiride-treated female rats

Previous studies indicate that the pineal gland alters prolactin secretion, and it was suggested that at least part of the effect of the pineal hormone melatonin on prolactin release may be mediated by the hypothalamic structures. In this study, pinealectomy and lesions of the suprachiasmatic nuclei were found to alter serum levels of prolactin in the same direction, an effect that was counteracted by daily afternoon melatonin administration. Melatonin, but not other pineal indoles, also prevented sulpiride-induced prolactin secretion in pinealectomized or suprachiasmatic nuclei-lesioned and ovariectomized rats, which suggested that the pineal gland can modulate prolactin secretion by acting through a dopamine mechanism independent of hypothalamic suprachiasmatic structures.