Showing papers on "Pinealocyte published in 2007"

The mammalian pineal gland: known facts, unknown facets.

Abstract: In the mammalian pineal gland, information on environmental lighting conditions that is neuronally encoded by the retina is converted into nocturnally elevated synthesis of the hormone melatonin. Evolutionary pressure has changed the morphology of vertebrate pinealocytes, eliminating direct photoreception and the endogenous clock function. Despite these changes, nocturnally elevated melatonin synthesis has remained a reliable indicator of time throughout evolution. In the photo-insensitive mammalian pineal gland this message of darkness depends on the master circadian pacemaker in the hypothalamic suprachiasmatic nuclei. The dramatic change in vertebrate pinealocytes has received little attention; here, we therefore link the known evolutionary morphodynamics and well-investigated biochemical details responsible for rhythmic synthesis of melatonin with recently characterized patterns of gene expression in the pineal gland. We also address the enigmatic function of clockwork molecules in mammalian pinealocytes.

Localization and biological activities of melatonin in intact and diseased gastrointestinal tract (GIT).

Abstract: Melatonin (MT), an indole formed enzymatically from L-trytophan (Trp), was first discovered in the bovine pineal gland in 1958 by Lerner et al. Melatonin is the most versatile and ubiquitous hormonal molecule produced not only in the pineal gland but also in various other tissues of invertebrates and vertebrates, particularly in the gastrointestinal tract (GIT). This review focuses on the localization, production, metabolism and the functions of MT in GIT and the duodenal unit (liver, biliary routes and pancreas), where multi-step biosynthetic pathways of this indole, similar to those in pinealocytes, have been identified. These biosynthetic steps of MT, including two major rate limiting enzymes; arylalkylamine-N-acetyltransferase (AA-NAT) and hydroxyindole-O-methyltransferase (HIOMT), transforming L-tryptophan (Trp), originally identified in pinealocytes, have been also detected in entero-endocrine (EE) cells of GIT, where this indole appears to act in endocrine, paracrine and/or luminal pathway directly or through G-protein coupled MT receptors. Studies of the distribution of MT in GIT mucosa showed that this indole is generated in GIT in much larger amounts than it is produced in the pineal gland. Melatonin acts in GIT, partly locally in paracrine fashion and is partly released into portal circulation, to be taken up by the liver. It is then metabolized and excreted with the bile to small bowel and finally returns to liver through entero-hepatic circulation. The production of MT by the pineal gland shows circadian rhythm with high night-time surge, especially at younger age, followed by the fall during the day-light time. As a highly lipophylic substance, MT reaches all body cells within minutes, thus, serving as a convenient circadian timing signal. Following pinealectomy, the light/dark cycle of plasma MT levels disappears, while its day-time blood concentration is maintained mainly due to its release from the GIT. According to our experience, after oral application of Trp, the plasma MT increases in dose-dependent manner both in intact and pinealectomized animals and humans, indicating that GIT but not the pineal gland is a source of this indole. In GIT MT exhibits a wide spectrum of activities such as circadian entrainment, antioxidant and free radicals scavenging activity, Melatonin (MT), an indole formed enzymatically from L-trytophan (Trp), was first discovered in the bovine pineal gland in 1958 by Lerner et al. Melatonin is the most versatile and ubiquitous hormonal molecule produced not only in the pineal gland but also in various other tissues of invertebrates and vertebrates, particularly in the gastrointestinal tract (GIT). This review focuses on the localization, production, metabolism and the functions of MT in GIT and the duodenal unit (liver, biliary routes and pancreas), where multi-step biosynthetic pathways of this indole, similar to those in pinealocytes, have been identified. These biosynthetic steps of MT, including two major rate limiting enzymes; arylalkylamine-N-acetyltransferase (AA-NAT) and hydroxyindole-O-methyltransferase (HIOMT), transforming L-tryptophan (Trp), originally identified in pinealocytes, have been also detected in entero-endocrine (EE) cells of GIT, where this indole appears to act in endocrine, paracrine and/or luminal pathway directly or through G-protein coupled MT receptors. Studies of the distribution of MT in GIT mucosa showed that this indole is generated in GIT in much larger amounts than it is produced in the pineal gland. Melatonin acts in GIT, partly locally in paracrine fashion and is partly released into portal circulation, to be taken up by the liver. It is then metabolized and excreted with the bile to small bowel and finally returns to liver through entero-hepatic circulation. The production of MT by the pineal gland shows circadian rhythm with high night-time surge, especially at younger age, followed by the fall during the day-light time. As a highly lipophylic substance, MT reaches all body cells within minutes, thus, serving as a convenient circadian timing signal. Following pinealectomy, the light/dark cycle of plasma MT levels disappears, while its day-time blood concentration is maintained mainly due to its release from the GIT. According to our experience, after oral application of Trp, the plasma MT increases in dose-dependent manner both in intact and pinealectomized animals and humans, indicating that GIT but not the pineal gland is a source of this indole. In GIT MT exhibits a wide spectrum of activities such as circadian entrainment, antioxidant and free radicals scavenging activity, cytoprotective, anti-inflammatory and healing efficacy of various GIT lesions such as esophagitis, gastritis, peptic ulcer, pancreatitis and colitis. This review concentrates on the generation and pathophysiological implication of MT in GIT and related organs.

Role of melatonin in upper gastrointestinal tract.

Abstract: Melatonin, an indole formed enzymatically from L-tryptophan, is the most versatile and ubiquitous hormone molecule produced not only in all animals but also in some plants. This review focuses on the role of melatonin in upper portion of gastrointestinal tract (GIT), including oral cavity, esophagus, stomach and duodenum, where this indole is generated and released into the GIT lumen and into the portal circulation to be uptaken, metabolized by liver and released with bile into the duodenum. The biosynthetic steps of melatonin with two major rate limiting enzymes, arylalkylamine-N-acetyltransferase (AA-NAT) and hydroxyindole-O-methyltransferase (HIOMT), transforming tryptophan to melatonin, originally identified in pinealocytes have been also detected in entero-endocrine (EE) cells of GIT wall, where this indole may act via endocrine, paracrine and/or luminal pathway through G-protein coupled receptors. Melatonin in GIT was shown to be generated in about 500 times larger amounts than it is produced in pineal gland. The production of melatonin by pineal gland shows circadian rhythm with high night-time peak, especially at younger age, followed by the fall during the day-light time. As a highly lipophilic substance, melatonin reaches all body cells within minutes, to serve as a convenient circadian timing signal for alteration of numerous body functions.. Following pinealectomy, the light/dark cycle of plasma melatonin levels disappears, while its day-time blood concentrations are attenuated but sustained mainly due to its release from the GIT. After oral application of tryptophan, the plasma melatonin increases in dose-dependent manner both in intact and pinealectomized animals, indicating that extrapineal sources such as GIT rather than pineal gland are the major producers of this indole. In the upper portion of GIT, melatonin exhibits a wide spectrum of activities such as circadian entrainment, free radicals scavenging activity, protection of mucosa against various irritants and healing of various GIT lesions such as stomatitis, esophagitis, gastritis and peptic ulcer. This review concentrates on the generation and pathophysiological implication of melatonin in upper GIT.

Melatonin biosynthesis in the thymus of humans and rats

Abstract: Melatonin is an indoleamine widely distributed in the evolution that shows a great functional versatility, playing an important role as a transmitter of photoperiodic information and exhibiting antioxidant, oncostatic, anti-aging and immunomodulatory properties. In vertebrates, this molecule is produced by the pineal gland and other extrapineal sites. The present study was carried out to investigate the presence of melatonin in thymus and the possibility of an endogenous melatonin synthesis in this organ, in which T cells are matured. In this work, we demonstrate in humans and rats that thymus contains melatonin, expresses the mRNAs encoding N-acetyltransferase and hydroxyindol-O-methyltransferase, the two key enzymes of the melatonin synthesis, and has this biosynthetic machinery activated. In addition, rat thymocytes cultured for 24 h exhibited high levels of melatonin. The results presented here suggest that human and rat thymuses are able to synthesize melatonin, which could have intracrine, autocrine and paracrine functions.

Evidence for differential photic regulation of pineal melatonin synthesis in teleosts

Abstract: The aim of this study was to compare the circadian control of melatonin production in teleosts To do so, the effects of ophthalmectomy on circulating melatonin rhythms were studied along with ex vivo pineal culture in six different teleosts Results strongly suggested that the circadian control of melatonin production could have dramatically changed with at least three different systems being present in teleosts when one considers the photic regulation of pineal melatonin production First, salmonids presented a decentralized system in which the pineal gland responds directly to light independently of the eyes Then, in seabass and cod both the eyes and the pineal gland are required to sustain full night-time melatonin production Finally, a third type of circadian control of melatonin production is proposed in tilapia and catfish in which the pineal gland would not be light sensitive (or only slightly) and required the eyes to perceive light and inhibit melatonin synthesis Further studies (anatomical, ultrastructural, retinal projections) are needed to confirm these results Ex vivo experiments indirectly confirmed these results, as while the pineal gland responded normally to day-night rhythms in salmonids, seabass and cod, only very low levels were obtained at night in tilapia and no melatonin could be measured from isolated pineal glands in catfish Together, these findings suggest that mechanisms involved in the perception of light and the transduction of this signal through the circadian axis has changed in teleosts possibly as a reflection of the photic environment in which they have evolved in

Rhythmic control of AANAT translation by hnRNP Q in circadian melatonin production

Abstract: The circadian rhythm of pineal melatonin requires the nocturnal increment of serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase [AANAT]) protein. To date, only limited information is available in the critical issue of how AANAT protein expression is up-regulated exclusively at night regardless of its species-specific mRNA profiles. Here we show that the circadian timing of AANAT protein expression is regulated by rhythmic translation of AANAT mRNA. This rhythmic control is mediated by both a highly conserved IRES (internal ribosome entry site) element within the AANAT 5' untranslated region and its partner hnRNP Q (heterogeneous nuclear ribonucleoprotein Q) with a peak in the middle of the night. Consistent with the enhancing role of hnRNP Q in AANAT IRES activities, knockdown of the hnRNP Q level elicited a dramatic decrease of peak amplitude in the AANAT protein profile parallel to reduced melatonin production in pinealocytes. This translational regulation of AANAT mRNA provides a novel aspect for achieving the circadian rhythmicity of vertebrate melatonin.

Cultured rat cortical astrocytes synthesize melatonin: absence of a diurnal rhythm

Abstract: Melatonin not only plays a major role in the regulation of circadian rhythms, but is also involved in antioxidative defense and immunomodulation. Circulating melatonin levels are derived primarily from the pineal gland while other sources of melatonin have also been reported. Here, we show for the first time that astrocytes from the rat cortex and glioma C6 cell line synthesize melatonin in vitro. In addition, we show the presence of serotonin, the precursor of melatonin and the two key enzymes in the pathway of melatonin synthesis, i.e. N-acetyltransferase and hydroxyndole-O-methyltransferase in the cultured rat cortical astrocytes. Release of melatonin into the culture medium showed no diurnal changes. These point to astrocytes as a local source of melatonin in the rat brain. Its exact physiological function remains a topic for future studies.

Evidence for melatonin synthesis in the rat brain during development

Abstract: Melatonin production is not restricted to the pineal gland. Several extrapineal sources of this indole such as retina, Harderian gland, and immune system are well documented. Melatonin of pineal origin is not present in the rat at early stages of development. To assess the potential capacity of local melatonin synthesis by the immature brain and to gain insight into the relationship between melatonin production by the brain (without the pineal gland) and pineal gland during rat development, the melatonin content as well as the expression and activity of the melatonin-synthesizing enzymes, N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT), were studied at fetal and postnatal stages. Moreover, melatonin-membrane receptor (MT(1)) expression was also analyzed. Both, the expression and activity of NAT and HIOMT were found in the brain with significant day/night differences in enzymes activities. Additionally, melatonin content was detected in all stages showing day/night differences depending on the stage of development. The brain nocturnal melatonin content was higher than diurnal content on postnatal day 16 and in adult rats which is in accordance with the pineal melatonin synthesis. To investigate the origin of this brain melatonin, pinealectomized rats were used and we found that the developing brain produced its own melatonin. Also, MT(1) expression was detected in brain during development. These results demonstrate that, when the pineal is not yet producing melatonin, there is melatonin synthesis by the brain that could be used as protection from free radical damage and/or could exert some actions through MT(1) receptors.

NeuroD1: developmental expression and regulated genes in the rodent pineal gland.

Abstract: NeuroD1/BETA2, a member of the bHLH transcription factor family, is known to influence the fate of specific neuronal, endocrine and retinal cells We report here that NeuroD1 mRNA is highly abundant in the developing and adult rat pineal gland Pineal expression begins in the 17-day embryo at which time it is also detectable in other brain regions Expression in the pineal gland increases during the embryonic period and is maintained thereafter at levels equivalent to those found in the cerebellum and retina In contrast, NeuroD1 mRNA decreases markedly in non-cerebellar brain regions during development Pineal NeuroD1 levels are similar during the day and night, and do not appear to be influenced by sympathetic neural input Gene expression analysis of the pineal glands from neonatal NeuroD1 knockout mice identifies 127 transcripts that are down-regulated (>twofold, p twofold, p < 005) According to quantitative RT-PCR, the most dramatically down-regulated gene is kinesin family member 5C (100-fold) and the most dramatically up-regulated gene is glutamic acid decarboxylase 1( fourfold) Other impacted transcripts encode proteins involved in differentiation, development, signal transduction and trafficking These findings represent the first step toward elucidating the role of NeuroD1 in the rodent pinealocyte

Increased vascular permeability and nitric oxide production in response to hypoxia in the pineal gland.

Abstract: This study examined the factors that may be involved in altering the function of pineal gland in hypoxic conditions. Adult Wistar rats were subjected to hypoxia and the pineal gland was examined for the mRNA and protein expression of hypoxia-inducible factor-1alpha (HIF-1alpha), vascular endothelial growth factor (VEGF), endothelial, neuronal and inducible nitric oxide synthase (eNOS, nNOS, iNOS) at 3 hr-14 days after hypoxic exposure by real time reverse transcription-polymerase chain reaction, Western blotting and immunohistochemistry. Upregulated mRNA and protein expression of HIF-1alpha, VEGF, eNOS, nNOS and iNOS was observed in response to hypoxia. VEGF concentrations as determined by enzyme immunoassay and nitric oxide (NO) production measured by colorimetric assay were significantly higher after hypoxic exposure when compared with the controls. Melatonin content of the pineal gland, as determined by ELISA, was significantly reduced after the hypoxic exposure. Dilated blood vessels expressing eNOS were observed in hypoxic rats. Cells immunoreactive for VEGF were identified as the astrocytes whereas those immunoreactive for iNOS were pinealocytes and macrophages. Our findings indicate that excess production of VEGF and NO in pineal gland in response to hypoxia may be involved in increased vascular permeability as evidenced by an enhanced leakage of rhodamine isothiocyanate (RhIC). The increased vascular permeability may allow free access of serum-derived substances in the pineal gland that may affect the secretory function of the pinealocytes. Administration of exogenous melatonin may be beneficial as it reduced VEGF concentration and NO production significantly in hypoxic rats, and leakage of RhIC was concomitantly reduced.

Cloning and early expression pattern of two melatonin biosynthesis enzymes in the turbot (Scophthalmus maximus).

Abstract: Melatonin biosynthesis from serotonin involves the sequential activation of the arylalkylamine N-acetyltransferase (AANAT) and hydroxyindole-O-methyltransferase (HIOMT). Photoperiod synchronizes a daily rhythm in pineal and retinal melatonin secretion through controlling AANAT activity. Teleost fish possess two Aanat, one expressed in the retina (AANAT1) and the other expressed in the pineal gland (AANAT2). We report here the full-length cloning of Aanat1, Aanat2, SmHiomt and Otx5 (orthodenticle homeobox homolog 5) in the turbot (Scophthalmus maximus, Sm), a flatfish belonging to an evolutionary recent group of Teleost. The temporal expression pattern of the genes investigated is consistent with the idea that OTX5 is needed for photoreceptor specification, and that the pineal gland differentiates before the retina. SmAanat2 expression remained pineal specific during the period of time investigated, whereas SmOtx5 and SmHiomt expressions were seen in both the retina and pineal gland. Our results do not support the existence of a second SmHiomt, as is the case for SmAanat. Neither SmAanat2 nor SmHiomt mRNAs displayed cyclic accumulation in the pineal organ of embryos and larvae maintained under a light-dark cycle from fertilization onward. This is in marked contrast with the situation observed with zebrafish Aanat2, indicating that the molecular mechanisms controlling the development of the pineal melatonin system have been modified during the evolution of Teleost.

The role of inducible repressor proteins in the adrenergic induction of arylalkylamine-N-acetyltransferase and mitogen-activated protein kinase phosphatase-1 in rat pinealocytes.

Abstract: In this study, we investigated the role of two inducible repressor proteins, inducible cAMP early repressor (ICER) and Fos-related antigen 2 (Fra-2) in the adrenergic induction of MAPK phosphatase-1 (MKP-1) as compared with their roles in the induction of arylalkylamine-N-acetyltransferase (AA-NAT) in rat pinealocytes. Treatment of pinealocytes with norepinephrine (NE) caused an increase in the mRNA and protein levels of MKP-1 and AA-NAT, as well as in the AA-NAT activity and melatonin production. NE stimulation also caused a simultaneous increase in the mRNA and protein levels of ICER and Fra-2. Transient knockdown of icer using adenovirus expressing small interfering RNA (siRNA) abolished the NE induction of icer expression but had little effect on the NE induction of mkp-1 or aa-nat expression. In contrast, pretreatment with adenovirus overexpressing icer was effective in reducing the NE induction of mkp-1 and aa-nat. The inhibitory effect of overexpressing icer was reversed by cotreatment with siRNA a...

The Role of Repressor Proteins in the Adrenergic Induction of Type II Iodothyronine Deiodinase in Rat Pinealocytes

Abstract: In this study, we investigated the transcriptional regulation of the adrenergic induction of type II iodothyronine deiodinase (Dio2) in rat pinealocytes. Treatment of pinealocytes with norepinephrine (NE) caused an increase in the mRNA level of Dio2 that peaked around 2 h and declined over the next 5 h. Both β- and α1-adrenergic receptors contributed to the NE induction of Dio2 expression through a cAMP/protein kinase A mechanism. In pinealocytes that had been stimulated by NE, inhibition of transcription by actinomycin had no discernible effect on Dio2 expression. In contrast, inhibition of protein synthesis by cycloheximide enhanced the NE induction of Dio2 expression, suggesting the involvement of a repressor protein. Transient transfection of pinealocytes with adenovirus expressing small interfering RNA against Fos-related antigen 2 (Fra2) enhanced the NE induction of Dio2 expression, whereas the effect of overexpression of the full-length transcript of Fra2 was inhibitory. Time-course study indicated...

Mitogen-activated protein kinase phosphatase-1 (MKP-1) preferentially dephosphorylates p42/44MAPK but not p38MAPK in rat pinealocytes.

Abstract: We recently reported a diurnal and norepinephrine (NE) -induced expression of mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1) in the rat pineal gland and postulated that this MKP-1 expression might impact adrenergic-regulated arylalkylamine-N-acetyltransferase (AA-NAT) activity via modulation of MAPKs. In this study, we investigated the effect of depletion of MKP-1 expression by using doxorubicin, a topoisomerase inhibitor that suppresses the expression of MKP-1 in other cell types and small interfering RNA targeted against Mkp1 in NE-stimulated pinealocytes. We found that both treatments were effective in inhibiting NE induction of MKP-1 expression. Moreover, both treatments also resulted in a prolonged activation of p42/44MAPK and an increase in AA-NAT induction by NE. In contrast, treatment of pinealocytes with PD98059, an inhibitor of MAPK kinase, reduced NE-stimulated AA-NAT activity. Interestingly, suppressing MKP-1 expression had no effect on the time profile of NE-stimulated p38MAPK activation. These results indicate that MKP-1 modulates the profile of AA-NAT activity by selectively shaping the activation profile of p42/44MAPK but not that of p38MAPK.

Expression of tranferrin receptors in the pineal gland of postnatal and adult rats and its alteration in hypoxia and melatonin treatment.

Abstract: Transferrin receptors (Tfrc) are membrane bound glycoproteins which function to mediate cellular uptake of iron from transferrin. We examined expression of Tfrc in the pineal gland of rats of different ages from 1 day to 12 weeks. The mRNA and protein expression of Tfrc increased up to 6 weeks of age and decreased in 12 week rats. Tfrc immunoreactivity was observed on pinealocytes and macrophages/microglia. By immunoelectron microscopy, the immunoreaction in pinealocytes was observed in the cytosol, on mitochondria and plasma membrane whereas in macrophages/microglia it was localized on the plasma membrane in 1-day to 2-week old rats. In older rats, the immunoreaction product in pinealocytes was associated with the plasma membrane and mitochondria only. Iron localization was observed in pinealocytes as well as macrophages/microglia. It is suggested that Tfrc are required for uptake of iron for cell proliferation and maturation in the pineal gland upto 6 weeks of age. The significance of Tfrc expression on mitochondria is speculative. They may be involved in iron transport to the mitochondria or for regulation of the secretory activity of pinealocytes. The TfrcmRNA and protein expression increased significantly in response to hypoxia in 12-week rats and this coincided with intense iron staining of the pinealocytes and macrophages/microglia. It is concluded that increased expression of Tfrc in response to hypoxia leads to excess cellular uptake of iron which may be damaging to the cells. Melatonin administration in hypoxic rats may prove to be beneficial as it reduced the Tfrc expression.

Peptidergic and Nitrergic Innervation of the Pineal Gland in the Domestic Pig: An Immunohistochemical Study

Abstract: Summary The presence and co-localization of vasoactive intestinal polypeptide (VIP), peptide N-terminal histidine C-terminal isoleucine (PHI), pituitary adenylate cyclase-activating peptide (PACAP), somatostatin (SOM), calcitonin gene-related peptide (CGRP), substance P (SP) and the neuronal isoform of nitric oxide synthase (NOS) were studied in neuronal structures of the pig pineal gland. Paraformaldehyde-fixed pineals of 3-month-old gilts were sliced into serial cryostat sections, which were subjected to a set of double immunofluorescence stainings. Based on the co-existence patterns of neuropeptides, five populations of nerve fibres supplying the pig pineal were distinguished: (1) PHI-positive, (2) PACAP-positive, (3) SOM-positive, (4) SP/CGRP-positive and (5) SP-positive/CGRP-negative. Only a subpopulation of PHI-positive fibres contained VIP at the level detectable by immunofluorescence. NOS was found in some intrapineal PHI- and VIP-positive fibres. PHI-, VIP- and NOS-positive nerve fibres were more numerous in the peripheral than in the central part of the pineal. PACAP-positive fibres were equally distributed within the gland. The density of SOM-positive fibres was higher in the ventro-proximal than in the dorso-distal part of the pineal. SOM was also detected in some neuronal-like cells or specialized pinealocytes situated in the central region of the gland. Two populations of fibres containing SP were found: CGRP-positive, present in the distal and central parts of the pineal as well as CGRP-negative, localized in the proximal compartment of the gland.

[Long round-the-clock illumination as a factor of accelerated ageing of pineal gland].

Abstract: On sexually matured male rabbits of Shinhilla breed kept in round-the-clock illumination within 5 months, dynamic of changes of structure of pineal gland was investigated It was found the gradual, progressing in time loss of pinealocytes amount, arising due to their apoptosis, which points out hypolinealism development Round-the-clock illumination should be considered as the factor promoting accelerated aging of pineal gland

Observation of adult yak pineal gland by light and electron microscopy

Abstract: Objective To study the characteristic of histological structure of the pineal gland of the adult yak. Methods HE and Achucarro-Hortega staining,light microscopy and transmission electron microscopy were used. Results The pineal gland was composed of pinealocytes,occasional glial cells,capillaries and neural elements.The pinealocyte appppered clear electronic density and its cytoplast included numerous mitochondria,rough and smooth endoplasmic reticulum,microtubules,microfilament and ribosome.Golgi complex was rare.The typical heterogenous organelle of pinealocyte of yak was spherical synaptic ribbon,which located near the plasma membrane.The glial cells contained abundant of mitochondria,and their processes which appeared bulbous invested the pineal periphery and incompletely separated the pinealocytes.Synapse and junctional complex existed between the pinealocytes and glial cells.Capillaries in pineal gland of the yak were belong to continuous capillaries,and pigment cells were observed around the vascellum in the gastr-distally of the pineal gland. Conclusion Neuroepithelial and epithelioglandular cell conjuction can be observed in the pineal gland of adult yak.Capillaries are belong to continuous capillaries.There are aboundant of organelle except Golgi complex in the pinealocyte.

Physiological Effects of Rhythmic Melatonin on Peripheral Cells in a Superfusion System

Abstract: Physiological Effects of Rhythmic Melatonin on Peripheral Cells in a Superfusion System (April 2007) Diana H. Tran Department of Industrial Engineering Texas A&M University Research Advisor: Dr. Vincent Cassone Department of Biology The immediate effects of melatonin from the pineal gland on peripheral cell types such as astrocytes, hepatocytes, and cardiac myocytes are relatively unknown. My research includes designing a superfusion or flow-through system that constantly pumps medium to light-entrained, chick pineal cells. The medium from the pinealocytes, enriched with pineal-specific secretions, will be directed to the above target cells, which are simultaneously housed in constant darkness. Radioimmunoassay for pineal melatonin and ELISA on the target cells’ secretions examines the effects of melatonin ex-vivo. This study will shed light on the direct effects of pineal melatonin on the central nervous system and peripheral organ cell types.