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PubMedDate not supplied

Tracing autonomic innervation of the rat pineal gland using viral transneuronal tracing.

We have used the neurotropic Bartha strain of pseudorabies virus (PRV) to characterise the pathway linking the endogenous circadian pacemaker of the suprachiasmatic nucleus (SCN) to the pineal gland. This low virulent strain of virus replicates within synaptically linked neurones and is ideally suited to visualise the multisynaptic pathways through which the SCN modulates the activity of the rat pineal gland. Using specific antibodies against PRV, we could follow the immunohistochemical pattern of the spatiotemporal passage of virus through the sympathetic trunk and the neuraxis. The time course of virus infection indicated that the most prominent pathway from the SCN to the pineal gland is via a final sympathetic innervation from the superior cervical ganglion (SCG). The pathway arises in the dorsomedial portion of the SCN from where neurones project to the dorsal parvicellular subdivision of the hypothalamic paraventricular nucleus (PVN) to form synaptic contact with neurones descending to the intermediolateral nucleus (IML) of the upper thoracic spinal cord. The neurones of the IML constitute the presynaptic sympathetic input synaptically connected to postsynaptic sympathetic neurones in the SCG which constitute the final input to the pineal gland. Removal of the superior cervical ganglion (SCGX) prior to viral infection completely abolished infection of neurones in this circuit. However, an additional parasympathetic projection from the superior salivatory nucleus via the sphenopalatine ganglion to the pineal gland was observed in SCGX animals.

Animals↗

PubMed2002

Presynaptic autoregulation of norepinephrine release from the sympathetic nerve fibers in the pineal gland of the domestic pig. Pharmacological characterization of alpha(2)adrenoceptors mediating this process.

BACKGROUND: Norepinephrine is the main neurotransmitter controlling melatonin secretion in the mammalian pineal gland. Presynaptic autoregulation of norepinephrine release from the sympathetic nerve fibers in the pineal gland is poorly known. METHODS: Uptake and depolarization-evoked release of (3)H-norepinephrine were investigated in vitro using pieces of the pig pineals. Specific antagonists and agonists of alpha(2)-adrenoceptors were employed for the characterization of alpha(2)-adrenoceptors involved in the autoregulation of depolarization-evoked release of norepinephrine in the pig pineal. RESULTS: The level of neuronal uptake of norepinephrine in the pig pineal was 3.5+/-0.9 pmol/h/mg of wet tissue and represented about 77% of the total tissue radioactivity. Potassium ions at concentration of 60 mM significantly evoked tritium release. This effect was abolished in the absence of extracellular Ca(2+) and was diminished in the presence of Cd(2+). Antagonists of alpha(2)-adrenoceptors increased depolarization evoked tritium release. The order of its potency (based on pED(30)) was rauwolscine > phentolamine > BRL 44408 > WB 4101> RS 79948 = yohimbine >> prazosin >> imiloxan. alpha(2)-agonists decreased K(+) evoked release of tritium with the order of potency: UK14,304 > norepinephrine = guanfacine > oxymetazoline. CONCLUSION: The processes of neuronal uptake and depolarization-evoked release of norepinephrine from the sympathetic nerve endings in the pig pineal gland have been demonstrated. The studies with the use of adrenergic antagonists and agonists indicate that the sympathetic nerve fibers in the pig pineal gland possess functional presynaptic alpha(2)-adrenoceptors, which are involved in norepinephrine release inhibition. Due to the pharmacological properties these receptors closely resemble the subtype alpha(2A).

Adrenergic Fibers↗

PubMed2003

Parkinsonism as an unusual presenting symptom of pineal gland teratoma.

We report a case of a 14-year-old Chinese boy with immature teratoma of the pineal gland who manifested with parkinsonism. Diagnostic evaluation revealed hydrocephalus and an immature teratoma of the pineal gland extending to the thalamus. An urgent ventriculoperitoneal shunt was inserted, and chemotherapy was given to reduce the tumor size. The tumor was completely excised 2 months after diagnosis with improvement of clinical signs and symptoms. His symptoms recurred 3 months later with sudden onset of obtundation, tremors, cogwheel rigidity, and marked bradykinesia. Magnetic resonance imaging (MRI) revealed a small enhancing lesion in the pineal region and progressive hydrocephalus on serial studies. He was treated with carbidopa/levodopa and amantadine, but marked improvement was only observed after reprogramming his VP shunt. Features consistent with the growing teratoma syndrome were noted during this period. These were progressive pineal gland tumor enlargement documented on MRI without increase in previously elevated alpha-fetoprotein levels. The tumor continued to enlarge despite gamma knife radiosurgery. Secondary parkinsonism is a rare presentation of pineal gland tumors and has not been reported in association with the growing teratoma syndrome.

Adolescent↗

PubMed1995

Immunohistochemical studies on supporting cells in the adrenal medulla and pineal gland of adult rat, especially on S-100 protein, glial fibrillary acidic protein and vimentin.

In the adrenal medulla and pineal gland, the morphological and chemical nature of supporting cells were examined immunohistochemically. In the adrenal medulla, supporting cells in noradrenaline (NA)-cell regions showed similar and intense immunoreactivities to the three glial marker proteins, S-100 protein, glial fibrillary acidic protein (GFAP) and vimentin, forming a network, while those in adrenaline (A)-cell regions were less numerous and their immunoreactivity was positive to S-100 protein but negative to GFAP and, at least in part, negative to vimentin. In the pineal gland, supporting cells in the stalk and the proximal region of the body portion formed a network and showed immunoreactivities to the three antibodies, while those in the distal region of the body portion were less numerous and their immunoreactivity was positive to S-100 protein and vimentin, but negative to GFAP. Thus, the distribution pattern and chemical nature of supporting cells showed regional differences in both glands. There were several similarities in supporting cells between those in NA-cell regions of the adrenal medulla and in the stalk and the proximal region of the body portion of the pineal gland, and also between in A-cell regions of the adrenal medulla and in the distal region of the body portion of the pineal gland, respectively. The biological and functional significances of these results are discussed.

Adrenal Medulla↗

PubMedDate not supplied

Ultrastructural interrelationship between the pineal gland and the testis in the male rat.

The ultrastructural interrelationship between the pineal gland and testis was evaluated in the rat. Wistar rats were divided into 6 groups. Groups I and II were sham-orchidectomized and orchidectomized rats, respectively. Rats in group III were orchidectomized and daily injected with testosterone propionate (TP) for 1 month. Groups IV and V were sham-pinealectomized and pinealectomized, respectively. Group VI was pinealectomized and daily injected with melatonin for 2 months. All animals were anesthetized with ketamine for fixation by vascular perfusion. Pineal glands of groups I, II, and III and the testes of groups IV, V, and VI were removed and weighed. All specimens were examined by electron microscopy. Orchidectomy caused an increase of lipid droplets, cytoplasmic dense bodies, and lysosomes. Rough endoplasmic reticulum, Golgi apparatus, and mitochondria were extensive in the cytoplasm. TP administration to orchidectomized rats resulted in formation of less extensive lipid droplets and mitochondria. In pinealectomized rats, golgi complex, mitochondria, and enlarged smooth endoplasmic reticulum were extensive in the cytoplasm of Leydig cells. Formation of cytoplasmic secretory granules and osmiophilic bodies was observed. Testicular weight increased compared to group IV. Melatonin decreased testicular weight in comparison to group V and prevented ultrastructural changes. Pinealectomy and orchidectomy caused hyperactivity in Leydig cells and pinealocytes, respectively, which suggests a mutual relationship between the pineal gland and testis in the rat.

Animals↗

PubMed2006

Histone H3 phosphorylation in the rat pineal gland: adrenergic regulation and diurnal variation.

In this study, we investigated phosphorylation of Ser10 in histone H3 by norepinephrine (NE) in the rat pineal gland. In whole-animal studies, we demonstrated a marked increase in histone H3 phosphorylation in the rat pineal gland during the first half of the dark period. Exposure to light during this period caused a rapid decline in histone H3 phosphorylation with an estimated t1/2 of less than 15 min, indicating a high level of dephosphorylation activity. Corresponding studies in cultured pineal cells revealed that treatment with NE produced an increase in histone H3 phosphorylation that peaked between 2 and 3 h and declined rapidly by 4 h. The NE-induced histone H3 phosphorylation was blocked by cotreatment with propranolol or KT5720, a protein kinase A inhibitor, but not by prazosin or other kinase inhibitors. Moreover, only treatment with dibutyryl cAMP but not other kinase activators mimicked the effect of NE on histone H3 phosphorylation. The NE-stimulated H3 phosphorylation was markedly increased by cotreatment with a serine/threonine phosphatase inhibitor, tautomycin or okadaic acid, supporting a high level of ongoing histone H3 dephosphorylation activity. Together, our results indicate that histone H3 phosphorylation is a naturally occurring event at night in the rat pineal gland that is driven almost exclusively by a NE-->beta-adrenergic-->cAMP/protein kinase A signaling mechanism. This transient histone H3 phosphorylation probably reflects the nocturnal activation of multiple adrenergic-regulated genes in the rat pineal gland.

Animals↗

PubMed1995

Arginine vasopressin stimulates 32P labeling of phosphoinositides in rat pineal gland.

The peptidergic innervation of the pineal gland contains arginine vasopressin (AVP) fibers. Since the site and molecular mechanism of AVP action on the pineal signal transduction has not yet been determined, we examined whether the inositol phosphate transduction system is involved. The phosphoinositide signaling system was studied by measuring metabolic turnover of phosphatidylinositol (PI), phosphatidylinositol phosphate (PIP) and phosphatidylinositol bisphosphate (PIP2), which reflects phosphoinositide cycle activation. AVP induced a significant increase in 32P labeling of PI, PIP and PIP2. The V1 receptor site(s) blocker for AVP abolished enhanced 32P labeling of PIP and PIP2. AVP was without effect on cAMP dependent phosphorylation. The data indicate that AVP activates the phosphoinositide signaling system via V1 receptors and is without effect on the cAMP system.

Animals↗

PubMed1999

A cytotoxic, apoptotic, low-molecular weight factor from pineal gland.

Previous studies suggest that the pineal gland may play a role in tumour growth inhibition. In this respect, melatonin, as the major hormone of this gland, has been extensively studied. However, there is growing evidence for the existence of other yet unknown pineal factors that may have tumour growth inhibiting properties. Here we describe the partial purification of a highly cytotoxic low molecular weight (<400 Da) hydrophilic fraction (designated F2M3R), starting from a porcine pineal extract (PE), via methanol precipitation followed by reverse-phase HPLC. F2M3R is cytotoxic for a highly apoptosis-resistant human erythroleukemia cell line (K562) at a concentration as low as 30 microg/ml. The viability of the cells was not influenced by an identical prepared porcine pituitary extract or by melatonin. PE induces apoptosis in K562 cells as indicated by three different criteria: morphology, in situ TUNEL assay and bi-parametric FACS analysis with annexin V and propidium iodide, but does not influence the viability of stimulated peripheral blood mononuclear cells. These observations warrant further purification and validation of the cytotoxicity in a panel of different human tumour and non-malignant cells.

Animals↗

PubMed1980

Taurine release from the pineal-gland is stimulated via a beta-adrenergic mechanism.

Pineal glands were prelabeled in organ culture with [14C]taurine, and then treated with biogenic amines. The rate of release of [14C]taurine was rapidly elevated by low concentrations of norepinephrine, apparently acting through a beta-adrenergic mechanism. The release was probably not due to a nonspecific change in membrane permeability, as a comparable release was not seen with [14C]glycine and [14C]alpha-aminoisobutyric acid. These findings suggest that the release of taurine may be related to or a reflection of the early events in adrenergic activation of the pineal gland, such as hyperpolarization of pinealocytes. The released taurine might also have an extracellular role as it has been recently shown that extracellular taurine can interact with pineal beta-adrenergic receptors to stimulate melatonin production. Thus, the released taurine could possibly act as an extracellular feedback messenger.

Acetyltransferases↗

PubMed2006

Melatonin synthesis in the human pineal gland: advantages, implications, and difficulties.

Rhythms in the mammalian pineal organ depend on afferent information that is derived from the endogenous clock residing in the hypothalamic suprachiasmatic nucleus (SCN). The best characterized function of the pineal gland is the nocturnally elevated synthesis of the hormone melatonin, which provides the body with the signal of the duration of the night period. The rate-limiting enzyme for melatonin synthesis is arylalkylamine N-acetyltransferase (AANAT). In contrast to the transcriptional regulation of the Aanat gene in rodents, a post-translational shaping of the melatonin pattern is indicated in the human pineal gland. Despite the fact that melatonin levels can be determined easily in various body fluids, the molecular elements involved in shaping the rhythmic hormone synthesis cannot be analyzed experimentally in the living organism. However, the use of post-mortem pineal material seems to constitute a valid approach to decipher the regulation of human melatonin synthesis.

Animals↗

PubMed1989

Two arylamine N-acetyltransferases from chicken pineal gland as identified by cDNA cloning.

A cDNA library prepared from the poly(A)-rich RNA of the chicken pineal gland obtained at night was screened with the 32P-labeled cDNA of arylamine N-acetyltransferase from the chicken liver recently isolated in this laboratory. Two positive clones (p-NAT-3 and p-NAT-10) that cross-hybridized with the liver cDNA were isolated. The cDNAs did not cross-hybridize each other under a high stringency, indicating that they corresponded to different mRNAs. When the cDNAs were inserted into an expression vector pcDL1 under the control of the early promoter of simian virus 40 and introduced into Chinese hamster ovary cells, both cDNAs expressed arylamine N-acetyltransferase activity in the transfected cells. The nucleotide sequences of the cDNAs were determined, from which amino acid sequences were deduced. Both cDNAs coded for 290 amino acids. Similarities in amino acid sequences were about 60% between p-NAT-3, p-NAT-10 and liver N-acetyltransferases. Poly(A)-rich RNA blot hybridization analysis indicated that p-NAT-3 cDNA detected a 2.2-kb band with the poly(A)-rich RNAs from the brain, gut and, less intensively, spleen, liver and kidney, while p-NAT-10 cDNA hybridized only with the poly(A)-rich RNA from the kidney. Neither cDNA detected any hybridization band with the poly(A)-rich RNA from the pineal gland, suggesting that the contents were low. Genomic Southern blot hybridization analysis showed that p-NAT-3, p-NAT-10 and liver N-acetyltransferases were encoded in a separate single gene. The properties of the enzymes expressed in the transfected cells were compared with N-acetyltransferases from the pineal gland, brain and kidney. On a DEAE-cellulose column, the kidney and p-NAT-10 enzymes appeared in the effluent fraction, whereas the brain and p-NAT-3 enzymes were eluted from the column with a gradient elution at 0.08 M NaCl. The supernatant of the pineal gland obtained in the daytime showed two peaks appearing in the effluent fraction and the eluate fraction at 0.08 M NaCl. The substrate specificity of these enzymes were examined with p-phenetidine, 2-aminofluorene, tryptamine and phenylethylamine as substrates. All the enzymes preferred arylamines to arylalkylamines, indicating that both p-NAT-3 and p-NAT-10 cDNAs encoded arylamine N-acetyltransferases.

Acetyltransferases↗

PubMed2006

Role of the pineal gland in ocular development of the chick in normal and constant light conditions.

PURPOSE: To evaluate the role of the pineal gland in development of the chick eye in normal and constant light (CL) conditions. METHODS: Chicks (Gallus gallus) were raised in either a 12-hour light-dark cycle (12L/12D) or in CL, with or without opaque, removable hoods that covered the top of the head for 12 hours each day. An additional group was raised with opaque eye occluders over the right eye for 12 hours daily. Half of the chicks in each group had their pineal glands surgically removed at 3 to 6 days after hatching. Corneal curvature was measured with keratometry, anterior chamber depth with ultrasound, and refraction with infrared photoretinoscopy. RESULTS: Pinealectomy does not affect the development of the chick eyes either in 12L/12D or CL. Covering the right eyes provided the same amount protection against CL's effects on the corneal curvature of both eyes, with or without pinealectomy. Pinealectomized chicks were not protected from CL's effects by 12L/12D head covers. A similar pattern of responses was obtained for refraction and anterior chamber depth. CONCLUSIONS: Although 12L/12D covering of the pineal gland can protect chick eyes from CL's effects (corneal flattening, shallowing of the anterior chamber, and hyperopia), the pineal gland does not appear to be necessary for normal growth in 12L/12D conditions, and its absence does not affect eye growth in CL conditions, with or without hoods or occluders. Pinealectomy does not influence the protection of an eye exposed to CL that is afforded by covering the other eye in a 12L/12D cycle.

Animals↗

PubMed2004

The effect of the transplanted pineal gland on the sympathetic innervation of the rat sublingual gland.

We investigated the effect of the pineal on sympathetic neurons that normally innervate the sublingual gland of the rat. When the pineal gland was transplanted into the sublingual gland, it remained as a distinct mass that was innervated by sympathetic axons. Injection of the retrograde tracer, Fast Blue, into the sublingual gland labelled sympathetic neurons in the ipsilateral superior cervical ganglion (SCG). Thirty per cent of all neurons labelled retrogradely by Fast Blue injection into transplanted pineal glands were immunoreactive for both neuropeptide Y (NPY) and calbindin. This combination is characteristic of sympathetic neurons innervating the pineal gland in its normal location, but not the sympathetic vasoconstrictor neurons normally innervating the sublingual gland. This, and our previous study in which the pineal gland was shown to similarly influence the phenotype of salivary secretomotor neurons, suggests that a range of different functional classes of sympathetic neuron are able to change their phenotype in response to signals released by the pineal gland.

Amidines↗

PubMed2003

Arterial vascularization of the pineal gland in the fetus of Zavot-bred cattle.

This study aimed at revealing arterial vascularization of the pineal gland of the Zavot-bred foetus. Twenty foetuses, regardless of their sex, at the age of 2-7 months were used. Coloured-latex was injected by way of both the right and left common carotid arteries. Then, dissection was performed and vessels nourishing the pineal gland were documented. The pineal gland is vascularized by a number of 2-5 central rami. A small vessel arising from each of the central rami in two foetuses (10%) was shown anastomosing with a branch of the cranial cerebral artery, which advances in cranio-caudal direction in the callosal groove. Hence, anastomoses were observed between several sub-branches of each caudal cerebral and cranial cerebellar arteries.

Animals↗

PubMed1990

Biochemistry of the pineal gland as an endocrine organ.

Experimental studies established a relationship between the pineal gland and various tumors a long time ago. Pineal extracts inhibit a wide spectrum of experimental tumors. Moreover, melatonin shows an anti-tumor action in both intact and pinealectomized animals. We have found that serum melatonin content is increased by 4 to 5-fold in melanoma patients. In normal subjects serum melatonin ranges from 0.47 to 0.65 nmol/l or 1.44 to 2.14 pg/mg serum protein. In contrast, in melanoma patients melatonin content of the serum varies between 2.07 to 6.20 nmol/l or 9.70 to 20.86 pg/mg serum protein. In another study, controls had melatonin levels of 0.47 +/- 0.02 nmol/l serum, or 2.07 +/- 0.24 pg/mg serum protein. In melanoma patients, the melatonin level was 1.65 +/- 0.10 nmol/l serum or 9.82 +/- 1.02 pg/mg protein. Post-mortem examinations revealed that the pineal pigment content was inversely related to the prevalence of malignancy, suggesting that a high melatonin level may be associated with an oncostatic action. Hydroxyindole-O-methyltransferase activity was significantly higher in the pineal gland of subjects that died from malignant tumors as compared with subjects that died from other causes.

Animals↗

PubMed1978

Innervation of the pineal gland in the mongolian gerbil (Meriones unguiculatus). A fluorescence microscopical study.

The innervation of the pineal gland in the Mongolian gerbil, Meriones unguiculatus, was investigated light microscopically by the Falck-Hillarp fluorescence technique and by conventional light microscopy. The pineal gland displayed a superficial portion just beneath the confluens sinuum and a deep part (lamina intercalaris) connected by a slender pineal stalk, which contained pinealocytes. The superficial part of the pineal gland consisted of dark-stained pinealocytes arranged in lobules, and separated by interstitial cells and connective tissue spaces. Many larger chromophobe cells were scattered throughout this region. A heavy catecholaminergic innervation of the superficial portion of the pineal organ, probably via the conarian nerve, with green fluorescent nerve fibres showing excitation/emission maxima of 415/475 nm was observed. Green fluorescent nerve fibres were also observed in the pineal stalk, from where some fibres turned rostrally indicating a nervous connection between the brain and the pineal organ. The pinealocytes showed a yellow fluorescence displaying a broad excitation curve with a maximum of 380-430 nm and an emission maximum at 505 nm. This indicates the presence of both serotonin and a catecholamine in the pinealocytes. Yellow fluorescence of the cells in the lamina intercalaris was also observed.

Animals↗

PubMed1984

12- and 15-lipoxygenases in rat pineal gland.

A whole organ or a homogenate of rat pineal gland was incubated with arachidonic Acid. Two predominant metabolites were identified by mass spectrometry to be 12-hydroxy-5,8,10,14-eicosatetraenoic acid and 10-hydroxy-11,12-epoxy-5,8,14-eicosatrienoic acid. 15-Hydroxy-5,8,11,13-eicosatetraenoic acid was also formed in a smaller amount. In addition, peroxy acids appeared rapidly only at the initial stage of reaction. In various parts of rat brain the 12-lipoxygenase activity was by far the highest in pineal gland, and less than 5% of the activity was found in pituitary gland and hypothalamus.

Animals↗

PubMed1997

Reproductive phase dependent effects of dietary L-tryptophan on biochemical constituents of pineal gland in male Indian palm squirrel, Funambulus pennanti.

Tryptophan serves as the substrate for the synthesis of various hydroxy- and methoxyindoles in the pineal gland. In the present study L-tryptophan (L-Trp; 0.5 mg/animal/day) was given in drinking water to male Indian Palm Squirrel for 30 days during reproductive active and pineal inactive phase (April) as well as during reproductive inactive and pineal active phase (December). During reproductive active phase serotonin (5-HT) content of pineal gland increased while accessory sex organ's weight decreased without affecting testes weight. During reproductive inactive phase all the biochemical constituents (protein, cholesterol and serotonin) of pineal gland decreased while testes and accessory sex organ's weight increased. This indicates a reproductive phase dependent effect of L-Trp on the biochemistry of pineal gland including 5-HT synthesis/release which in turn (via melatonin) manipulates reproductive functions of this rodent.

Animals↗