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An immature teratoma arising in the pineal gland in a 27-year-old male was shown to present an isochromosome 12p as evidenced by cytogenetic and fluorescence in situ hybridization analysis. As i(12p) is characteristic of gonadal germ cell tumors, this case indicates that similar genetic pathways may operate in gonadal and intracranial teratomas.
Ultrastructural changes in the pineal gland were studied in relation to migration, breeding and moult. Sizes of pinealocytes and that of their nuclei were greatest in the Spring premigratory and postmigratory, and moult phases. The ratio of nuclear size to cell size was greatest for the breeding phase and lowest for the Fall premigratory and postmigratory phases. The Golgi complex was most prominent during premigratory and breeding phases. Mitochondria which were numerous in all phases except during moult, were markedly enlarged during breeding and Fall premigratory phases. Dense-core vesicles were predominant in Spring postmigratory and moult phases. In glial cells, lipoid inclusions were abundant in Spring premigratory and postmigratory, and breeding phases. Glycogen granules were abundant in Spring postmigratory, breeding and moult phases. Large vacuoles were present in Fall premigratory phase. Lamellar membraneous whorls were often present near luminal spaces during Spring premigratory and postmigratory, and breeding phases. The endothelial cells of pineal capillaries during Spring and Fall premigratory phases, contained numerous vesicles, some of which were freely dispersed in the cytoplasm while others were fused to the cell membrane, suggestive of transendothelial transport of vesicular substances.
The ultrastructure of the rat pineal gland was studied from 75 days until 10 months of age. Type I pinealocytes of young adults showed nuclei with dispersed chromatin, numerous infoldings of the nuclear envelope and well developed nucleoli. The cytoplasm displayed many mitochondria and clusters of smooth endoplasmic reticulum. With increasing age, there was a clear increase in the number of dense bodies or lysosomes in the Type I pinealocyte. The changes in the Type II pinealocytes with age were mainly in nuclear shape and in the appearance of lipofuscin granules.
Foci of differentiating heterophilic granulocytes in the pineal gland were studied by light and electron microscopy in chickens, from hatching until 56 weeks of age. Foci of granulopoiesis could be seen in the first 24 hours after hatching. Thereafter, their number and cellular density increased, becoming highest at 2 weeks. From then on, numbers decreased progressively until foci disappeared at 18 weeks. Granulopoietic cells established local associations with fibroblast-like cells. Mature granulocytes reached the bloodstream by the 2 mechanisms described for hematopoietic cells in the bone marrow, either passing between lining cells or through the cytoplasm of lining cells.
Histamine (HA) potently stimulated cyclic AMP accumulation in intact pineal glands taken from light-exposed chicks. The action of HA was stronger in the presence of forskolin and the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). The effect of HA was mimicked by HA H1- and H2-receptor-selective agonists in the following order of potency: HA > 4-methylhistamine (H2) > 2-methylhistamine (H1) > 2-thiazolylethylamine (H1) >> dimaprit (H2). The HA H3-receptor-selective agonist (R)alpha-methylhistamine was poorly active. The effect of HA was antagonized by selective H2-receptor blockers (tiotidine > oxmetidine > cimetidine = ranitidine) and was not significantly affected by the selective H1- and H3-receptor blockers mepyramine and thioperamide. A detailed analysis of an antagonistic action of ranitidine (versus HA) revealed a noncompetitive mode of action of the H2 blocker. The stimulatory action of the H1 agonist 2-thiazolylethylamine (both under basal conditions and in the presence of forskolin or IBMX) was not significantly influenced by three H1-receptor-selective blockers (mepyramine, triprolidine, and diphenhydramine), but it was totally counteracted by ranitidine. Using accepted selective agonists and antagonists of the HA H1, H2, and H3 receptor we were unable to identify clearly the receptor subtype mediating the HA action on the cyclic AMP-generating system of the chick pineal. It is suggested that the receptor under consideration may represent either an H2-like (in terms of mammalian criteria) or avian-specific HA receptor. The data suggest that HA may be considered a modulator of the pineal activity in chicks.
The effects of the pineal gland on diurnal endocrine function were studied in male rats. Pineal stimulation by exposure to short daily photoperiods (1L:23D) did not alter plasma levels of testosterone, thyroid-stimulating hormone (TSH) or growth hormone (GH) as compared with those of controls maintained under normal (12L:12D) lighting. Pinealectomy lowered diurnal testosterone levels and increased TSH levels in animals maintained under 1L:23D lighting. Pinealectomy also altered the TSH rhythm and shifted the peak in testosterone levels but did not abolish hormonal rhythms. Active immunization against melatonin and its precursor, N-acetylserotonin (NAS), significantly reduced diurnal androgen levels and elevated TSH levels in animals exposed to short photoperiods, but the 24-hour rhythms persisted. Plasma GH exhibited a diurnal rhythm in animals kept under short photoperiods but GH levels were not affected by any of the above treatments. These data suggest that melatonin and/or NAS may be involved in the maintenance of basal testosterone and TSH levels. The pineal may not be involved in generating hormonal rhythms; however, it may have a role in entraining TSH and testosterone rhythms to environmental lighting.
HPLC with EC detector was used to study the red light effect on the rhythmicity of catecholamines (NE, DOPAC and dopamine) and indoleamines (NAS, 5-HT, 5-HIAA) in the pineal glands and retinas of the Sprague-Dawley rat. We found the prominent nocturnal elevations of NAS in rat pineal glands and the suppression of the NAS but not the elevation of 5-HT and 5-HIAA after red light exposure at night. Our data show two findings: metabolic pathway of the indoleamines (5-HT, 5-HIAA and NAS) after red light exposure at night may be different from those by white light. Second, the increased HIOMT activity that effects on 5-HT and 5-HIAA may also be involved in the indoleamine formation after red light exposure at night.
1. The adrenoceptor in a mouse pineal gland tumour cell line (PGT-beta) was identified and characterized using pharmacological and physiological approaches. 2. Adrenaline and noradrenaline, adrenoceptor agonists, stimulated cyclic AMP generation in a concentration-dependent manner, but had no effect on inositol 1,4,5-trisphosphate production. Adrenaline was a more potent activator of cyclic AMP generation than noradrenaline, with half maximal-effective concentrations (EC50) seen at 175+/-22 nM and 18+/-2 microM for adrenaline and noradrenaline, respectively. 3. The addition of forskolin synergistically stimulated the adrenaline-mediated cyclic AMP generation in a concentration-dependent manner. 4. The pA2 value for the specific beta2-adrenoceptor antagonist ICI-118,551 (8.7+/-0.4) as an antagonist of the adrenaline-stimulated cyclic AMP generation were 3 units higher than the value for the betaI-adrenoceptor antagonist atenolol (5.6+/-0.3). 5. Treatment of the cells with adrenaline and forskolin evoked a 3 fold increase in the activity of serotonin N-acetyltransferase with the peak occurring 6 h after stimulation. 6. These results suggest the presence of beta2-adrenoceptors in mouse pineal cells and a functional relationship between the adenylyl cyclase system and the regulation of N-acetyltransferase expression.
We have previously measured the individual content of immunoreactive vasopressin (AVP), oxytocin (OT) and vasotocin (AVT) in 155 human pineal glands, and report here identification and measurement of the neurophysin (Np) content of the same glands, using specific homologous human neurophysin I (HNp I) and neurophysin II (HNp II) radioimmunoassays. Median values for HNp I were for men 47 ng/gland (range, 5 to 1360) and for women 24 ng/gland (range, 5 to 1000); median values for HNp II were respectively 7 ng/gland (range, 2 to 191) and 15 ng/gland (range, 2 to 356) with no significant difference between men and women for HNp I and HNp II but a significant difference (p less than 0.001) between HNp I and HNp II for both sexes. Gel filtration showed that pineal neurophysins were eluted at the same volume as both standard Np and Np from human posthypophyses used as controls. HNp I correlated both with AVP (rs = 0.54 for men and 0.55 for women) and OT (rs = 0.86 for men and 0.57 for women) but not with AVT, while HNp II correlated with AVP (rs = 0.52 for men and 0.53 for women) and OT (rs = 0.92 for men and 0.50 for women) but not with AVT. This study thus confirms the presence of two neurophysins in the human pineal gland and further indicates that they are related to AVP and OT concentrations in the same gland. The results also imply, however, that the presence of immunoreactive AVT (more probably a closely related peptide) is independent of the neurophysins.
The effects of pineal gland on kidney-adrenal axis have been studied in male rats. Rats were pinealectomized and exposed to a photoperiod of 12 h light: 12 h dark. Plasma renin activity (PRA), corticosterone and corticotropin (ACTH) levels were measured at 10, 20 and 35 days postpinealectomy. Pinealectomy increased corticosterone and ACTH levels and decreased PRA in all age groups. A significant negative correlation was found between corticosterone and PRA, which suggest that changes in PRA were due to changes in circulating corticosterone, via feedback mechanism on renin secretion. On the other hand, melatonin administration prevents these effects of pinealectomy. It is suggested that the lack of this pineal indol is responsible for the pinealectomy-induced alterations in male rats.
The monoclonal antibody WF6, raised against purified Torpedo nicotinic acetylcholine receptor (nAChR) was used to study the distribution of cholinoceptors in the rat pineal gland by means of Western blot analysis, light- and electron microscopy. The immunoblot analysis using homogenized pineal gland revealed a labeled protein band of apparent molecular weight 40 kDa which was identified as alpha-subunit of a nAChR. In the light microscope, approximately one-fourth of the pinealocytes exhibited cytoplasmic immunoreactivity (IR) of varying density. In the electron microscope, IR was seen as patchy staining of cell membranes of pinealocyte somata and processes. Presynaptic IR material was not found. Distribution and intensity of the observed IR was not significantly different in pineal sections from ganglionectomized rats, nor were any alterations found that would relate to the animals' sex or to the time of killing (day vs night). Our results provide further evidence for the existence of cholinergic receptors in the mammalian pineal. They may be important for the understanding of the gland's regulation.
The 105,000 X g supernatant fraction of bovine pineal gland contains a phosphodiesterase activity that hydrolyzes both cyclic AMP and cyclic GMP. The rate of hydrolysis is 4-5 times greater with cyclic GMP as substrate than with cyclic AMP. Chromatography of supernatant fraction on Sephadex G-150 resolves phosphodiesterase activity into two fractions designated PDE I and PDE II. These are distinguishable on the basis of their molecular size, substrate specificity, and kinetic parameters. PDE I hydrolyzes cyclic GMP at a faster rate than cyclic AMP and has a molecular weight of 163,000. PDE II appears to be a smaller protein with a molecular weight of 24,400 and is specific for cyclic AMP. PDE I has apparent Km values of 83 and 53 micron for cyclic AMP and cyclic GMP, respectively, whereas PDE II exhibits an apparent Km value of 330 micron for cyclic AMP. With subsaturating concentrations of cyclic AMP as substrate, the phosphodiesterase activity of PDE I is inhibited by the addition of cyclic GMP. However, PDE II activity remains unaffected by cyclic GMP even at concentrations up to 125 micron. PDE II appears to be thermostable, losing only 20% of its activity on heating at 80 degrees for 2 min. Similar treatment completely abolishes the enzyme activity of PDE I.
A standardized removal and dissection procedure is presented for human infant brain. A previously unreported cistern of the pineal gland must be severed at autopsy in order to preserve the gland's anatomic integrity during brain removal. Utilization of these methods to investigate Sudden Infant Death Syndrome brain tissue should facilitate interdisciplinary studies and comparisons of inter agency findings. We use these dissection procedures to extend our findings on reduced pineal gland size as an anatomic marker assisting the forensic pathologist in making the diagnosis of Sudden Infant Death Syndrome.
Synthesis and release of melatonin were studied in pineal explants from 14- (young) and 60-day-old ('maturing') male Long-Evans rats with or without added thyroid hormone, triiodothyronine (T3), at or near physiological levels and under light and dark conditions. Incubation for 6 hr (1200-1800) was in a synthetic medium; melatonin was measured by radioimmunoassay (RIA). In light, T3 increased melatonin levels in pineal and medium of cultures from either young or maturing animals. In dark, T3 decreased melatonin levels in the pineals of either age, but was without significant effect on levels in the medium. Since it is known from other work that 14-day-old rat pineal glands do not yet have a complete sympathetic innervation system, it is here doubly evident that T3 can modulate directly pineal synthesis and release of melatonin, and may not depend upon a mature sympathetic innervation. Light in the studied conditions was permissive from the stimulatory action of T3 on pineal synthesis and release of melatonin in vitro.
D-Neopterin at 10 microM delayed start of the decline of serotonin N-acetyltransferase (NAT) activity from the peak level in the cycle exhibited by chick pineal glands cultured under standard conditions in the dark. A less marked retardation of decline of NAT activity was found with glands cultured under diurnal illumination or those exposed prematurely to light. There were no significant effects of neopterin on the increases of NAT activity or peak levels of activity developed. The pteridine also retarded loss of NAT activity from the peak level developed in the dark when the time of explanting into culture was later in the (solar) day, but not when it was earlier. Neopterin had no effect on the cycle in cyclic GMP content of cultured chick pineal glands.
In the present paper, we review the cartesian description of the neuromuscular reflex and the sensorial perception as well as the hypothetical role of the pineal gland on these functions. We analyze the historical bases which support the physiological cartesian doctrine and, from the perspective of our present knowledge, we evaluate the contributions of Descartes to the scientific progress of his time. In the elaborated psychophysiological theory of the french wise, the pineal gland plays a pivotal role, raising the theory that the human soul could be located within this organ.
Patterns of hormone release from peptide- and monoamine-hormone secreting cells were compared. LH, GH and PRL secretion from rat anterior pituitary cells and melatonin secretion from the rat pineal gland fragments were studied in a dynamic, in vitro system. The following fundamental differences were found: 1. Adenohypophysial cells respond to a specific stimulus (releasing hormones) with hormone secretion within seconds. There is a 90-minute lag, however, between the beginning of specific stimulation (norepinephrine, 1 microM for 30 min) and the onset of melatonin (MT) release from the pineal cells. 2. Hormone secretion from the pituitary cells returns to the basal value five to 10 minutes after the stimulus has been stopped. Once initiated, MT release from the pineal lasts for five to seven hours even if the NE stimulus was stopped one hour before the beginning of the MT response. 3. A transitory increase in potassium concentration (by 50-100 mM) induces a sharp, distinct rise of hormone secretion from pituitary cells, similar in shape and size experienced as response to releasing hormone stimulation. Pineal cells do not respond to elevation of potassium concentration at all. 4. High concentration of tropic hormones can be extracted from pituitary cells at the end of the superfusion experiment. Their hormone content is equivalent to the amount released from non-stimulated cells in a 50 to 80 hours period (LH and GH cells). No significant quantity of MT can be extracted from non-stimulated, disintegrated pineal cells. This diversity in the control of hormone secretion from anterior pituitary and the pineal gland can be considered as a model for peptide and monoamine-hormone producing glands.
Hybridomas that produce monoclonal antibodies to bovine hydroxyindole O-methyltransferase have been established by immunizing a mouse with hydroxyindole O-methyltransferase partially purified from bovine pineal glands followed by fusion of the spleen cells with myeloma NS-1 cells. Twenty-three clones have been isolated by screening the medium by two different methods. These clones produced various antibodies with different binding properties. Most of the antibodies belonged to IgG1 subtype, while 7 clones produced IgG2 alpha or IgG2 beta antibodies. Three antibodies inhibited enzymatic activity, whereas others did not. Antibodies of 7 clones recognized enzyme protein denatured with sodium dodecyl sulfate, while other antibodies reacted only with native enzyme protein. Thus a variety of monoclonal antibodies will offer us a good tool for immunohistochemical localization of the enzyme, immunoaffinity purification of hydroxyindole O-methyltransferase, and isolation of the cDNA clones encoding it. We also report here on the immunohistochemical demonstration of hydroxyindole O-methyltransferase in bovine pineal gland and a new immunoaffinity procedure to purify the enzyme to homogeneity by use of monoclonal antibodies.