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PubMed1981

Radioimmunoassay of arginine vasopressin, oxytocin and arginine vasotocin-like material in the human pineal gland.

Specific radioimmunoassays (RIAs) have been developed for arginine-vasopressin (AVP), oxytocin (OT), and arginine-vasotocin (AVT): they can detect 2.5 pg, 5 pg and 1 pg of hormone respectively. The three antisera employed in the RIAs in the present study all had a specificity that discriminated between the three neuropeptides and thus allowed their accurate measurement in each of 157 human pineal glands. Immunoreactive AVP was found to have a mean concentration of 306.4/+-27.6 (SE) pg/gland in the 1389 pineals where it was at level higher than the detection limit. Immunoreactive OT was determined as 386.3/+-42.1 pg/gland in the 110 pineals where it was measurable, and the mean apparent immunoreactive AVT content was 44.6/+-3.6 pg/gland in the 110 pineals where it was found at detectable levels. Cross-reactivity with AVP or OT cannot account for the immunoreactive peptide content of human adult pineal glands was demonstrated as a function of: (1) sex, (2) time of death, (3) cause of death, (4) age (18 to 85 yr old) or (5) delay between death and gland removal over the range of 4 to 48 hr. While the presence of AVP and OT is not surprising, indications of an immunoreactive AVT may in fact reflect a peptide which is closely related to AVT and cross-reacts in the AVT RIA.

Antibody Specificity↗
PubMed1989

An immunocytochemical study of thyrotropin releasing hormone in the porcine, ovine and rodent pineal gland.

A biotin-avidin immunoperoxidase method was used to localize a pineal TRH-like compound in histological sections. TRH-like immunoreactivity was observed in porcine, ovine and rodent pineal glands. The immunoreaction was located on positively stained cell bodies and cellular processes throughout the glands. The exact location of the TRH (in pinealocytes, glial cells, or both) as well as the physiologic significance of the immunoreactive material remain to be elucidated.

Animals↗
PubMed1997

I. Role of the pineal gland in multiple sclerosis: a hypothesis.

Despite intensive research over the past several decades, the etiology and pathogenesis of multiple sclerosis (MS) remain elusive. The last 20 years have seen only meager advances in the treatment of the disease in part because too much attention has been devoted to the process of demyelination and its relationship to the neurologic symptoms and recovery of the disease. A host of biological phenomena associated with the disease involving interactions among genetic, environmental, immunologic, and hormonal factors, cannot be explained on the basis of demyelination and, therefore, require refocusing attention on alternative explanations, one of which implicates the pineal gland as the pivotal mover of the disease. This review summarizes the evidence linking dysfunction of the pineal gland with the epidemiology, pathogenesis, clinical manifestations, and course of the disease. The pineal hypothesis of MS also provided the impetus for the development of a novel and highly effective therapeutic modality, one that involves the transcranial application of AC pulsed electromagnetic fields in the picotesla flux density.

Adolescent↗
PubMed1998

A novel isoform of the orphan nuclear receptor RORbeta is specifically expressed in pineal gland and retina.

RORbeta is a member of the nuclear hormone receptor superfamily whose ligand is unknown. Expression of RORbeta is confined to the central nervous system and its pattern suggests that this orphan nuclear receptor is implicated in the processing of sensory information and in circadian timing. In rats, RORbeta mRNA levels oscillate robustly in pineal gland and retina, displaying a 24h rhythm. Here we report the cloning of the cDNA of a novel isoform of RORbeta from rat pineal tissue. Expression of this isoform, called RORbeta2, is confined to pineal gland and retina and strongly increases at night. RORbeta2 shares common DNA- and putative ligand-binding domains with the canonical RORbeta (referred to as RORbeta1), but is characterized by a different amino-terminal domain. This structural difference renders RORbeta2 much more selectively binding to DNA than RORbeta1. Moreover, in contrast to RORbeta1, the novel isoform efficiently activates transcription also in non-neuronal cell lines. Thus, the two RORbeta isoforms are likely to regulate different sets of genes in different physiological contexts. 1998 Elsevier Science B.V.

Animals↗
PubMed1987

In vitro effect of neuropeptide Y on melatonin and norepinephrine release in rat pineal gland.

1. To study neuropeptide Y (NPY) effect on melatonin production, rat pineal explants were incubated for 6 hr with 10-1,000 nM NPY in the presence or absence of 10 microM norepinephrine (NE). Melatonin content in the pineal gland and media was measured by radioimmunoassay (RIA). 2. NPY (10-1,000 nM) increased melatonin production and, at 10 or 100 nM concentrations (but not 1,000 nM), enhanced NE stimulation of melatonin production. 3. NPY (1,000 nM) impaired 3H-labeled transmitter release induced by a K+ depolarizing stimulus in rat pineals incubated with 3H-NE. 4. These results suggest that NPY affects both pre- and postsynaptic pineal mechanisms.

Animals↗
PubMed2003

Circularly polarised MF (500 micro T 50 Hz) does not acutely suppress melatonin secretion from cultured Wistar rat pineal glands.

Magnetic fields (MF, 50 Hz) have been proposed to affect melatonin production in mammals; however, there is very little data about the mechanism by which this possible interaction may occur. Here we describe results from the first study in which circularly polarised 50 Hz MF have been administered to isolated pineals in highly controlled conditions. Melatonin release from isolated Wistar rat pineal glands, dissected 2 h after light onset ZT 2, was measured in a flow through culture system, during and after exposure to a 4 h MF similar in nature and magnitude to that produced in extremely close proximity to a high voltage power line (500 micro T 50 Hz circularly polarised). Melatonin release from isolated pineals was comparable to that observed in previous studies, plateauing to approximately 100 pg/ml/30 min. No significant alterations in pineal melatonin release were caused by exposure to the MF when compared to sham exposure (< 1 micro T). These results suggest that if the circadian system is acutely responsive to MF exposure of this nature, an intact circadian axis may be necessary in order to observe an effect on the production on melatonin from the pineal gland

Animals↗
PubMed1991

Determination of 5-methoxyindoles in pineal gland and plasma samples by high-performance liquid chromatography with electrochemical detection.

A liquid chromatographic analysis with electrochemical detection of 5-methoxytryptamine, 5-methoxytryptophol, 5-methoxyindoleacetic acid and melatonin is described. Optimal elution conditions were determined by studying several variables: pH, buffer salt, counter ion and organic modifier. Measurement of 5-methoxyindoles in the pineal gland and plasma of hamsters has been performed after extraction. This method is specific and sensitive, and enables detection of 5-methoxyindoles in a pool of two hamster pineal glands. This is also the first time that these three 5-methoxyindoles have been measured simultaneously in plasma.

5-Methoxytryptamine↗
PubMed2006

Lcg is a light-inducible and clock-controlled gene expressed in the chicken pineal gland.

The circadian clock is an autonomous biological clock that is entrainable to environmental 24-h cycles by receiving time cues such as light. Generally, light given at early and late subjective night, respectively, delays and advances the phase of the circadian oscillator. We previously searched for the chicken pineal genes that are induced by light in a phase-dependent manner. The present study undertook cDNA cloning and characterization of a gene whose expression was remarkably up-regulated by light at late subjective night. The mRNA level of this gene exhibited robust diurnal change in the pineal gland, with a peak in the early (subjective) day under light-dark cycles and constant dark condition, and hence it was designated Lcg (Light-inducible and Clock-controlled Gene). Chicken Lcg encodes a coiled-coil protein composed of 560 amino acid residues. Among chicken tissues, the pineal gland and the retina exhibited relatively high expression levels of LCG. LCG was colocalized with gamma-tubulin, a centrosomal protein, when expressed in COS7 cells, and LCG is the first example of a clock-related molecule being accumulated at the centrosome. Coimmunoprecipitation of LCG with gamma-tubulin in the chicken pineal lysate suggests a link between the circadian oscillator and the centrosomal function.

Amino Acid Sequence↗
PubMed1980

Pineal gland lipid characterization in the seven-week-old cockerel (Gallus domesticus).

The composition of pineal gland lipid was characterized in young cockerels. The total pineal lipid was 159.7 microgram, which was equivalent to 3.0 and 14.1% of fresh and dry tissue weight, respectively. The major phospholipids were phosphatidyl choline (63.1%), phosphatidyl ethanolamine (16.1%), and sphingomyelin (14.7%). Palmitic, stearic, oleic, and arachidonic acids composed 27.9%, 19.4%, 15.8%, and 13.7% of the phospholipid fatty acid fraction, respectively. Free fatty acids (38.4%), cholesterol (17.6%), and cholesterol ester (17.2%) comprised the major fraction of neutral lipids, while the predominant neutral lipid fatty acids were palmitic (26.0%) and oleic (23.8%). The percentage of wet tissue weight that is lipid in the pineal is considerably less when compared to brain cortex or retina. When chickens are compared to several mammalian species, there is little difference in percent lipid per milligram pineal tissue, but definite differences exist in the percentage of various lipid classes.

Animals↗
PubMed1990

"Synaptic" ribbons in the pineal gland of the horse.

Previous studies on the ultrastructure of the horse pineal gland did not report the presence of "synaptic" ribbons, functionally enigmatic pinealocyte organelles regularly occurring in other mammalian species. The aim of the present study was to reinvestigate the horse pinealocyte in this respect. Careful investigations here reported allowed detection of "synaptic" ribbons in the pinealocytes of all the examined animals, although in a relatively low number (5.4 +/- 2.0 per 20,000 microns 2 of pineal tissue; mean +/- SD). The ultrastructure of "synaptic" ribbons in pinealocytes of the horse resembles closely that observed in other mammalian species.

Animals↗
PubMed1977

On the presence of different populations of pinealocytes in the mammalian pineal gland.

The different categories of cells described by many authors in the pineal gland of mammals have been critically considered. In some mammalian species, two different populations of pinealocytes have been observed. To each of these populations a specific secretory process can be attributed. One is characterized by the formation of granular vesicles originating from the Golgi apparatus, the other by the formation of material directly from the cisterns of the granular endoplasmic reticulum. Both of these secretory processes appear to be also present in the pineal of the mole, the hedgehog, and the rat, mammals in which generally only one population of pinealocytes has been described. The physiological consequences of these findings have been discussed.

Animals↗
PubMed1994

Density of peptide histidine-isoleucine- and vasoactive intestinal peptide-immunoreactive nerve fibers in the sheep pineal gland is not affected by superior cervical ganglionectomy.

Peptide histidine-isoleucine (PHI) is a regulatory peptide, synthesized as part of the same propeptide that includes also vasoactive intestinal peptide (VIP). The present study describes the distribution of PHI-immunoreactive nerve fibers in the sheep pineal organ and compares their location with the distribution of VIP-immunoreactive fibers in both normal and superior cervical ganglionectomized sheep in order to elucidate the origin of the PHI/VIP immunoreactive nerve fibers. Several PHI-immunoreactive nerve fibers were present in the meninges and in the pineal capsule. Numerous positive nerve fibers entered the pineal gland and travelled within connective tissue spaces. Individual PHI-positive nerve fibers were either smooth, without specialization, or varicose. Generally VIP- and PHI-immunoreactive fibers were located close to connective septa and blood vessels. However, many PHIergic and VIPergic fibers possessing varicosities of variable sizes were also dispersed between pinealocytes. The distribution, density, and morphology of PHI- and VIP-immunoreactive fibers in the sheep pineal gland were similar. In superior cervical ganglionectomized animals, intrapineal VIP- and PHI-immunoreactive nerve fibers were present with the same density as in control animals. In agreement, the concentration of immunoreactive VIP and PHI did not change after ganglionectomy. No VIP- and PHI-immunoreactive cell bodies were observed in the superior cervical ganglia. Thus this study shows that the intrapineal VIP- and PHI-immunoreactive nerve fibers do not originate from the sympathetic superior cervical ganglion.

Animals↗
PubMed1994

Circularly polarized 50-Hz magnetic field exposure reduces pineal gland and blood melatonin concentrations of Long-Evans rats.

In order to determine if pigmented rats also exhibit melatonin suppression like that described for albino rats exposed to circularly polarized, 50-Hz, 1-muT magnetic fields for 6 weeks, two experiments were conducted with Long-Evans rats. The field-exposed experimental group received circularly polarized, 50-Hz, 1-muT magnetic fields for 6 weeks, the concurrent sham-exposed control group was exposed to the stray field of 0.02 muT. In addition, prior to the exposure experiment, two cage-control groups were placed in the facility for 6 weeks without activation of the 50-Hz magnetic field generation apparatus. Rats were sacrificed at 12.00 and at 24.00 h for collection of plasma and pineal gland: melatonin was determined by radioimmunoassay. Significant reductions of plasma and pineal gland melatonin contents were observed at 0.02 muT as compared to the control values, and a further reduction was observed at 1 muT. As do albino rats, pigmented rats rats also exhibit melatonin suppression when exposed to time-varying magnetic fields.

Animals↗
PubMed1995

Fusaric acid in Fusarium moniliforme cultures, corn, and feeds toxic to livestock and the neurochemical effects in the brain and pineal gland of rats.

Fusaric acid is produced by several species of Fusarium, which commonly infect corn and other agricultural commodities. Since this mycotoxin may augment the effects of other Fusarium toxins, a gas chromatography/mass spectrometry method of analysis in feeds was developed. Fusaric acid was analyzed as the trimethylsilyl-ester from F. moniliforme-cultures, -contaminated corn screenings, and feeds toxic to livestock. The mycotoxin was found in all samples and ranged from 0.43 to 12.39 micrograms/g sample. Also, fusaric acid was tested for its neurochemical effects in the brain and pineal gland of rats. Animals were dosed intraperitoneally (100 mg/kg body weight) 30 min prior to the onset of the dark phase (lights out) and the effects were studied at 1.5, 3.5, and 5.5 h after treatment. Brain serotonin (5HT), 5-hydroxyindoleacetic acid (5HIAA), tyrosine (TYRO), and dopamine (DA) were increased (P < 0.05) by fusaric acid, and norepinephrine (NEpi) was decreased (P < 0.05). Analogously, DA in the pineal gland increased and NEpi decreased (P < 0.05). Pineal N-acetylserotonin (NAc5HT) was increased (P < 0.05), whereas pineal 5HT and its two major metabolites 5HIAA and 5-hydroxytryptophol (5HTOL) decreased (P < 0.05). Elevated brain TYRO and brain and pineal DA, with decreased NEpi, may be consistent with fusaric acid's partial inhibitory effect on tyrosine-hydroxylase and its inhibitory effect on dopamine-beta-hydroxylase, respectively. Elevated pineal Nac5HT is consistent with decreased pineal 5HT and the increased pineal DA, and support the dopaminergic stimulatory activity of the enzyme responsible for the conversion of 5HT to NAc5HT. This is the first report of fusaric acid's in vivo effect on pineal DA, NEpi, 5HT, and NAc5HT in rats, and a relation for the effects on TYRO, 5HT, and 5HIAA in brain tissue. The results indicate fusaric acid alters brain and pineal neurotransmitters and may contribute to the toxic effects of Fusarium-contaminated feeds.

Animal Feed↗
PubMed1988

Ultrastructural examinations of the zone function of the rat pineal gland in terms of mitochondrial bioenergetics.

Membrane-membrane relations in the pineal gland were analysed. It was found that neighbouring pinealocytes may be in different mitochondrial configurational states. The pinealocytes lying next to the same glial cell and around nerve endings are in one metabolic state. Close to blood vessels this uniformity occurred when the perivascular space was surrounded by one glial cell.

Animals↗
PubMed1983

Monoamino-oxidase activity in rat pineal gland. Histochemical studies.

Monoamine-oxidase (MAO) activity was detected in rat pineal gland with dopamine, 5-hydroxytryptamine (5-HT), norepinephrine and tryptamine as substrates, and nitroblue tetrazolium salt as electron acceptor. Pinealocytes stained deeply when 5-HT was the substrate. Dopamine and tryptamine substrates gave similar patterns, with moderate activity in the pinealocytes. Norepinephrine reactivity was detected in the nerve-endings.

Animals↗
PubMed1984

Arginine vasotocin (AVT), an alleged hormone of the mammalian pineal gland.

Arginine vasotocin has been proposed as a hormone of the mammalian pineal gland. This claim is largely based on biological and immunological results, although some chemical evidence has also been provided. Yet, more and more researchers have recently disclaimed the presence of this nonapeptide in mammalian tissue. The currently available evidence is critically reviewed exposing the dispute as a real one urgently requiring final settlement.

Amino Acid Sequence↗
PubMed1993

Effect of magnetic field on pineal gland volume and pinealocyte size in the rat.

Light microscopic observations on the superficial pineal gland of Wistar-King rats were made to examine whether or not pineal volume and pinealocyte size, expressed as nuclear density, at daytime or nighttime are affected by long-term exposure to 50 Hz rotating magnetic field (MF) at 5.0 microT. Determinations of pineal volume and pinealocyte size were repeated twice (April and October) during the year. Size of pinealocytes in MF-exposed and sham-exposed rats exhibited, in addition to the difference between peripheral and central regions, regional differences in a proximodistal direction; pinealocytes in the distal and middle-peripheral regions were usually larger than those in the proximal and middle-central regions at daytime or nighttime. In October, distal and proximal pinealocytes showed significant day-night changes in size in sham-exposed rats, but not in MF-exposed animals. The situations in the two groups were almost reversed in April. Significant day-night differences were scarcely found in pinealocyte size in the middle region in the two groups. Throughout the study, pineal volume and pinealocyte size in each region were generally the same between MF-exposed and sham-exposed rats at daytime or nighttime. The results suggest that pinealocytes in the distal and proximal regions, but not those in the middle region, are affected by MF-exposure; day-night differences in sizes of distal and proximal pinealocytes appear in April and disappear in October under the influence of MF. MF may exert an effect on mechanisms controlling day-night rhythms of pinealocyte size in the rat.

Animals↗