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At least 937 records · Page 52Linked to original sources
PubMed1987

Beta-adrenergic binding sites in fetal rat central nervous system and pineal gland: their relation to other receptor sites.

Regional development of beta-adrenergic binding sites in the rat fetal central nervous system and pineal gland were studied in relation to the ontogeny of different drug and neurotransmitter binding sites. 3H-dihydroalprenolol labels the olfactory bulb very early in fetal life. A comparatively early development of binding sites is also seen for benzodiazepines during late gestation. 3H-serotonin, 3H-muscimol, 3H-GABA and 3H-(N)-methylscopolamine additionally label the olfactory bulb, revealing quite different patterns. Around gestational day 16, beta-adrenergic sites were found in the neocortex, then in choroid plexus and in the pineal gland. Besides beta-adrenergic, only 3H-flunitrazepam binding sites are detectable in the fetal eye, the latter with a more restricted regional distribution. In the fetal pineal, beta-adrenergic, muscarinic cholinergic and serotonergic binding sites appear at different times in gestation. In the neocortex a variety of binding site patterns develop. Two more general types can be distinguished: appearance along with caudorostral maturation of the brain and appearance within distinct brain regions, possibly related to local differentiation processes. The simultaneous onset of various binding sites in distinct areas of the fetal brain might result in higher sensitivity of individual brain areas to drugs.

Animals↗
PubMed1993

Noradrenergic regulation of c-jun expression in the rat pineal gland in culture: positive and negative components.

One component of the nocturnal changes in cellular immediate-early gene expression in the rat pineal gland is a decrease in c-jun expression, mediated through beta-adrenoceptors. An in vitro study of the intracellular mechanisms which control c-jun expression has now shown that a norepinephrine-induced increase in c-jun mRNA levels in organ-cultured pineals is differentially modulated by protein kinase inhibitors; N-(2-guanidinoethyl)-5-isoquinolinesulfonamide (HA-1004) potentiated the response; however, in the presence of 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), a significant decrease in c-jun mRNA was found. Treatment with HA-1004 alone elevated the level of c-jun mRNA, H-7 alone was without effect. Forskolin together with 3-isobutyl-1-methylxanthine suppressed c-jun, whereas phorbol 12,13-dibutyrate raised c-jun mRNA levels. The results demonstrate opposing pathways for c-jun regulation in the pineal gland, and indicate that the nocturnal attenuation of c-jun expression involves selective activation of a negative pathway which may be linked to cAMP.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1989

Ontogeny of tyrosine hydroxylase-positive but dopamine beta-hydroxylase-negative neuron-like cells in the pineal gland of golden hamsters.

The ontogeny of tyrosine hydroxylase (TH)-positive but dopamine beta-hydroxylase (DBH)-negative neuron-like cells in the pineal gland of golden hamsters was investigated by double immunostaining. These cells first appeared on the 6th postnatal day and thereafter increased in number. On the other hand, TH- and DBH-positive nerve fibers, probably originating from the superior cervical ganglion, were already present in the pineal gland at birth.

Animals↗
PubMed2006

Effect of TNF-alpha on the melatonin synthetic pathway in the rat pineal gland: basis for a 'feedback' of the immune response on circadian timing.

A retino-hypothalamic-sympathetic pathway drives the nocturnal surge of pineal melatonin production that determines the synchronization of pineal function with the environmental light/dark cycle. In many studies, melatonin has been implicated in the modulation of the inflammatory response. However, scant information on the feedback action of molecules present in the blood on the pineal gland during the time course of an inflammatory response is available. Here we analyzed the effect of tumor necrosis factor-alpha (TNF-alpha) and corticosterone on the transcription of the Aa-nat, hiomt and 14-3-3 protein genes in denervated pineal glands of rats stimulated for 5 hr with norepinephrine, using real-time reverse transcription-polymerase chain reaction. The transcription of Aa-nat, a gene encoding the key enzyme in melatonin biosynthesis, together with the synthesis of the melatonin precursor N-acetylserotonin, was inhibited by TNF-alpha. This inhibition was transient, and a preincubation of TNF-alpha for more than 24 hr had no detectable effect. In fact, a protein(s) transcribed, later on, as shown by cycloheximide, was responsible for the reversal of the inhibition of Aa-nat transcription. In addition, corticosterone induced a potentiation of norepinephrine-induced Aa-nat transcription even after 48 hr of incubation. These data support the hypothesis that the nocturnal surge in melatonin is impaired at the beginning of an inflammatory response and restored either during the shutdown of an acute response or in a chronic inflammatory pathology. Here, we introduce a new molecular pathway involved in the feedback of an inflammatory response on pineal activity, and provide a molecular basis for understanding the expression of circadian timing in injured organisms.

Animals↗
PubMed2001

Roles of nocturnal melatonin and the pineal gland in modulation of water-immersion restraint stress-induced gastric mucosal lesions in rats.

The roles of melatonin and the pineal gland in the circadian variation of water-immersion restraint stress-induced gastric mucosal lesions in rats were investigated. Fasted rats were subjected to water-immersion restraint stress during both the diurnal and nocturnal phases of a light:dark cycle. Pinealectomized and sham-operated rats were also subjected to water-immersion restraint stress at night. The lesion area after 4 hr of stress during the dark phase was significantly lower than in light-phase controls. Pinealectomy increased the lesion area in the dark phase, compared to the sham operation, but this effect was counteracted by intracisternal melatonin preadministration at a dose of 100 ng/rat. Melatonin concentrations in control rats during the light phase were significantly increased 4 hr after water-immersion restraint stress. In contrast, melatonin concentrations 4 hr after water-immersion restraint stress in the dark phase were significantly depressed compared with the control levels at the corresponding time. Melatonin levels after stress exposure were markedly decreased in pinealectomized rats as compared with sham-operated rats. These results suggest that circadian rhythm has an important role in the formation of stress-induced gastric mucosal lesions in rats and that melatonin responses to water-immersion restraint stress differ between day and night. The pineal gland modulates the stress response and melatonin contributes to gastric protection via a mechanism involving the central nervous system.

Animals↗
PubMed1981

Pineal gland and melatonin influence on chronic alcohol consumption by hamsters.

Male golden hamsters preferentially consume alcohol solution when given a free-choice between water and the alcohol solution. The pineal gland has been implicated as influencing the predilection for the ethanol solution. Melatonin, a pineal hormone, was administered either daily for 11 weeks as a subcutaneous injection (25 micrograms/animal) or weekly as a subcutaneous beeswax implant (1 mg melatonin/24 mg beeswax) for 5 weeks to hamsters allowed a free-choice between water or a 10% ethanol solution. Food, water and alcohol consumptions were measured on a daily basis. Animals treated by daily injection with melatonin consumed slightly less ethanol than animals not given melatonin. In light-deprived animals given chronic implants of melatonin, alcohol consumption was reduced when compared to alcohol consumption by light-deprived hamsters not receiving melatonin. Melatonin treatment also resulted in reducing daily total fluid intake as well as ethanol consumption in light-deprived hamsters. The results indicate that the pineal gland may influence fluid consumption in the hamster, and indirectly alters the propensity of the hamster to consume alcohol.

Alcoholism↗
PubMed1981

The role of the pineal gland in neuroendocrine control mechanisms of neoplastic growth.

A survey of papers read during a workshop held in Vienna, 1977, is given showing that the pineal gland can be considered a model for research on neuroendocrine control mechanisms in neoplastic growth. From data obtained by different authors it can be concluded that the role of the pineal indole melatonin is very important in regard of the incidence and the development of tumours. On the basis of all the facts mentioned in this paper it is obvious that pineal gland activity should be included into the neuroendocrine factors studied in relation with oncogenic processes. For future research a number of experimental approaches, which need special emphasis, are recommended.

Animals↗
PubMed1978

Non-reproductive systems and the pineal gland.

The paper reviews the data accumulated on the interrelationship between the pineal gland and the central nervous system as evidenced by induced neuroanatomical, biochemical and hormonal changes taking place in one system following the activation or inhibition of the other. The possible role of the pineal in modifying behaviour and its involvement in mental impairment is consequently discussed. Further questions dealt with are, whether in addition to the pineal effect via the hypothalamic-pituitary axis on the peripheral non-reproductive glands, thyroid and adrenals, a direct feedback mechanism exists between their hormones and the pineal. The effect of the pineal on the endocrine glands which are known not to be under the direct control of the hypothalamo-pituitary axis, pancreas, thymus and parathyroid, is also discussed.

Adrenal Glands↗
PubMed1978

[Demonstration of pineal gland and pituitary involution in mice poisoned with carbon tetrachloride].

Ingestion of carbone tetrachloride by male C3H Orleans mice determines an involution of the pineal gland and of the hypophysis, as well as extensive lesions of the hepatic parenchyma. There may exist in these animals a higher blood-level of glucocorticoids, as this has been shown to be the case in men suffering from cirrhosis or hepatitis. Involution of the pineal gland in cases of stress, as has been shown by various authors, would result from an entirely different mechanism, that is by increased secretion of corticoadrenal hormones.

Adrenal Cortex Hormones↗
PubMed1994

Regulation of hydroxyindole-O-methyltransferase gene expression in the pineal gland and retina.

Hydroxyindole-O-methyltransferase (HIOMT) catalyzes the final step of melatonin biosynthesis and appears to be specifically expressed in the pineal gland and in the retina. This review deals with the regulation of HIOMT by environmental light and with the developmental aspects of HIOMT expression in chicken and rat. Early studies based on HIOMT activity measurements and more recent studies involving cDNA hybridization to HIOMT mRNA are taken into consideration. Together, the data reveal that long term regulation of HIOMT by light would rely on a day/night rhythm of HIOMT gene transcription, coupled to a slow turnover of the protein. Rapid changes in HIOMT mRNA levels and early expression during embryonic development suggest that further studies on this gene may shed light on the molecular mechanisms involved in the differentiation of the melatoninergic function and in its regulation by light, both in the pineal gland and in the retina.

Acetylserotonin O-Methyltransferase↗
PubMed2000

Immunohistochemical study of the glutamate transporter proteins GLT-1 and GLAST in rat and gerbil pineal gland.

Several investigations performed during this decade have led to the hypothesis that small secretory vesicles of pinealocytes (generally referred to as synaptic-like microvesicles, SLMVs) are components of a system for intercellular paracrine communication between pineal cells, which shares many features with the process of synaptic neurotransmission. According to a recent study, one parallel that can be drawn to synaptic signal transduction seems to be the presence of pineal re-uptake systems for messenger molecules released from SLMVs, i.e. for neuroactive amino acids such as L-glutamate. In order to further characterize these uptake mechanisms, we have carried out an immunohistochemical study to explore the presence and cellular localization of the glutamate transporters GLT-1 and GLAST in rat and gerbil pineal glands. GLT-1 and GLAST were always detected in a subpopulation of pineal parenchymal cells in both species. Using immunostaining of serial semithin sections with antibodies against marker proteins of pineal cell types, GLT-1- and GLAST-positive cells were identified as interstitial glial cells. In addition, some pinealocytes also displayed immunoreactivity for GLT-1. In contrast to current thinking, our findings show that GLT-1 is not the only glutamate transporter subtype expressed in the pineal gland. Moreover, our observations point to a significant participation of interstitial cells in the process of pineal glutamatergic communication, reminiscent of the role of glial cells during glutamatergic neurotransmission in the central nervous system.

ATP-Binding Cassette Transporters↗
PubMed1995

Pineal gland and melatonin affect testicular status in the adult marsh rice rat (Oryzomys palustris).

The effects of the presence or absence of the pineal gland and of melatonin administration were examined on testicular maintenance, regression, and recrudescence in adult male rice rats. Pinealectomy at the beginning of the study caused significant testicular regression in animals housed on both long (16L:8D) and short (12L:12D) photoperiods (Experiment 1). Sham-operated males maintained testicular weight on 16L:8D and underwent testicular regression on 12L:12D. The magnitude of testicular regression in pinealectomized animals was reduced relative to that of sham-operated animals housed on a short photoperiod and occurred on a different time course. Animals pinealectomized after testicular regression had occurred on 12L:12D demonstrated delayed photostimulated testicular recrudescence when housed on 16L:8D, while spontaneous testicular recrudescence was unaffected in animals maintained on 12L:12D (Experiment 2). Administration of melatonin via subcutaneous implants at the beginning of the study (Experiment 3) produced similar effects on testicular function attributed to pinealectomy in Experiment 1. Finally, melatonin implants administered after the testes regressed on 12L:12D delayed both photostimulated and spontaneous testicular recrudescence in animals housed on long or short photoperiods, respectively (Experiment 4). These results suggest a role for both the pineal gland and melatonin at various stages of the annual reproductive cycle of the male rice rat.

Analysis of Variance↗
PubMed1992

Daily rhythm of aspartate aminopeptidase activity in the retina, pineal gland and occipital cortex of the rat.

The levels of specific soluble aspartyl aminopeptidase activity were assayed in retina, occipital cortex, anterior pituitary, posterior pituitary, pineal gland and serum of adult male rats, using Asp-2-naphthylamide as substrate, in a 12:12 h light:dark cycle (7-19 h light). Significant diurnal variations appeared in retina, pineal gland, occipital cortex and serum. In addition, different patterns of diurnal variation of the enzymatic activity were observed in the tissues analyzed. A regular increase of the activity was noticed at the end of the dark period in all the tissues as a common feature, except in serum, in which the enzymatic activity reached a peak in the middle of the light period, decreasing progressively during the dark hours. After the last hours of darkness, the pattern of variation in the activity differed in each tissue. These diurnal variations in aspartyl aminopeptidase activity could reflect the functional status of its putative endogenous substrates, such as angiotensin II, and it may also suggest the existence of differential regulatory mechanisms associated with each location.

Aminopeptidases↗
PubMedDate not supplied

Effect of pineal gland on testosterone release in vitro.

We studied the effect of hCG, aminoglutethimide and pineal effluent on the basal testosterone secretion by superfused adult rat interstitial cells. The period used to determine the mean rates of release was 120-240 min. after the start of superfusion i.e. when basal secretory rate was stable. A 2 h administration of hCG (10 mUI/ml) induced a rapid increase in testosterone output while aminoglutethimide (100 microM) decreased it. Basal testosterone release was not modified when interstitial cells were superfused with effluent of a chamber containing 1, 2 or 4 pineal glands. These results suggest that pineal secretory products exert no direct acute action on testosterone biosynthesis by rat interstitial cells.

Aminoglutethimide↗
PubMed1990

Light affects neonatal rat pineal gland N-acetyltransferase activity by an extra-retinal mechanism.

To determine whether extra-retinal mechanisms mediate photoperiodic changes in neonatal rat pineal gland N-acetyltransferase activity, 4-day-old intact or bilateral orbital enucleated rats were killed during the dark phase of the lighting cycle, either in darkness or following 4 hr exposure to fluorescent light. Light suppressed the high nighttime N-acetyltransferase activity equally in intact and enucleated pups. Subsequent studies showed that at least 0.5 hr exposure and nocturnal illuminances of 109 microW/cm2 or greater were required to cause statistically significant reductions in the activity of the enzyme in 4-day-old rats. Taken together, these data indicate that relatively intense environmental light can affect neonatal rat pineal gland biochemistry via extraretinal mechanisms.

Acetyltransferases↗
PubMed1990

[Effects of the deafferentation of the pineal gland by bilateral ablation of superior cervical sympathetic ganglia on the autumnal recrudescence of testicular activity in mink].

The effects of deafferentation of the pineal gland on the autumnal recrudescence of testicular activity in mink raised in a natural photoperiod were studied following bilateral superior cervical ganglionectomy. Animals were operated at four different times between the end of summer and the end of autumn, i.e., when daylength at this latitude naturally decreases from 12.5 to 8.5 hrs. Deafferentation of the pineal gland on September 15 (daylength 12.5 hrs.) or October 20 (daylength 10.5 hrs.), when testis volume and plasma testosterone are normally reduced to a minimum, caused these values to remain at the same low levels during the whole observation period. In contrast deafferentation on October 28 (daylength 10 hrs.), did not present the recrudescence of testicular activity, but the rise was transitory and testis development was incomplete. Finally, when the operation was performed on December 1, during the phase of natural sexual resumption, the increases in testicular volume and plasma testosterone were not affected at all and the profiles of their subsequent variations conformed to the patterns of intact animals.

Animals↗
PubMed1985

Role of the pineal gland in the photoperiodic control of reproductive and non-reproductive functions in mink (Mustela vison).

Mink are long-lived mammals that exhibit seasonal changes in body weight, gonadal activity, pelage and plasma prolactin levels. Mating in February-March is followed by an obligatory delay in implantation during which the corpora lutea stay quiescent. All these events are controlled by annual variations in daylength. The role of the pineal gland and its product, melatonin, in conveying photic information to the target organs has been studied. Pineal denervation by bilateral ablation of the cervical superior ganglia rendered the mink unresponsive to artificial manipulations of the daily photoperiod: prolactin and progesterone secretion and the spring moult were no longer stimulated by long days or inhibited by short days in pregnant females; in the same way the increase in body weight in late summer and the autumn moult were no longer advanced by artificial shortening of the photoperiod. Pinealectomy seemed to desynchronize body weight, prolactin and moulting cycles from those in intact mink. Melatonin injections reproduced the effects of short days on hormonal secretion during the delayed implantation period. Melatonin capsules given to males during the phase of testicular activity delayed the decrease in body weight, testicular regression and onset of the spring moult exactly as did short days. In contrast, melatonin administered during the phase of testicular inactivity triggered an increase in body weight, the onset of the spring moult and testicular recrudescence in this short-day breeder. These results support the hypothesis that in mink all photoperiodic signals are conveyed by the pineal gland. But although the pineal seems essential for the seasonal timing of the cycles, it does not modify the events themselves once they are initiated.

Animals↗
PubMed1990

[Morphodynamic response of the pineal gland to an initial stress attack--the effect of morphine].

The possible participation of a stimulated ACTH secretion in the promotion of the pineal gland reactive response under conditions of injection stress was studied. Morphine was used as a pharmacological mimicry of the stress-induced ACTH outflow in the post-injection period of 10-45 min. In animals subjected to injection stress (administration of the physiological solution), in the 10-th min. light pinealocytes exhibited a significant rise in the relative volume of the GER field and the Gogli apparatus, as well as bouquets of presecretory or secretory forms of the cell processes and frequent extrusion of lipid droplets. From 20-th min. on, the relative volume of their membranous elaborative compartment gradually decreased, the cell processes were missing and the lipid droplet extrusion was rare. The rich arbourisation of the GER tubules, the active appearance of the Golgi apparatus and a more abundant occurrence of lipid droplets--a picture which persisted even in 30 min.--showed that the intensified elaborative activity of dark pinealocytes, a minor cell population, was of longer duration in comparison with light pinealocytes. The subsequent fall in their stress-reactive response points out that the function of light and dark pinealocytes is driven by different regulative systems. Based on the principle that the function is the reflection of morphometabolic changes, in can be concluded that 10 min. after the injection act, the pineal gland has a short-term crescendo of its stress-reactive response. The morphine injection did not cause any significant changes in both pinealocyte populations in 10 min. A considerable increase of the relative volume of the constituents of the membrane elaborative compartment was found in light pinealocytes in the next observational periods, i.e., in the 20-th and the 30-th min. The lack of any conspicuous signs of an enhanced secretory activity, in contrast with frequent findings of lipid droplets and prosecretory granules, shows that the facilitation of the elaborative activity leads more to a restitution and increase of the pinealocyte potential than to a stimulation of their current secretion. Characteristic of this period was a frequent finding of newly generated lipid droplets. Their presence within the fields of GER tubules, as well as the communication of the lumens of these tubules with the matrix of the arising lipid droplet suggest a close connection of lipid droplets with the pinealocyte peptidergic activity Unexpected was the finding of a conglomerate of fasciculated lamellae--structures of a so far unknown function.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗