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Lipoxygenation of docosahexaenoic acid by the rat pineal body.

Based on the inhibitor profile, production rate, and stereochemical purity of the hydroxylated products, it was demonstrated that lipoxygenation in rat brain occurs only in the pineal. Both positional and stereochemical specificities of the hydroxylation were observed only in pineal, clearly indicating that only the pineal is capable of lipoxygenating polyunsaturated fatty acids among the rat brain regions examined. Cerebral cortex also produced hydroxy products; however, they were racemic mixtures, indicating that peroxidation was responsible for their production. Rat pineal homogenate, obtained after the brain was perfused, metabolized [14C]docosahexaenoic acid ([1-14C]22:6n3) to monohydroxy derivatives, primarily by the 12- and, to a lesser extent, by the 15-lipoxygenase (LO) reaction. The resulting metabolites were 14(S)- and 17(S)-hydroxydocosahexaenoic acid (HDoHE), as determined by reversed-phase HPLC, chiral-phase HPLC, thermospray liquid chromatography-mass spectrometry, and gas chromatography-mass spectrometry. Because blood was removed by perfusion of the brain before incubation, it was clear that the observed LO activity was not due to contamination with blood cell components. The production rate of 17-HDoHE from 22:6n3 was higher than that of 15-hydroxyperoxy-5,8,11,13-eicosatetraenoic acid from 20:4n6, whereas 12-LO activity toward these two substrates was comparable. These monohydroxy metabolites were also detected in the pineal body lipid extract using negative ion chemical ionization mass spectrometry. This is the first observation of endogenous production of hydroxylated compounds in pineal. The ratio of endogenous 15-LO to 12-LO products was considerably higher than that of the in vitro production from exogenous substrate. In some cases, 15-LO products were the major LO metabolites present in the lipid extract of pineal body for both 20:4n6 and 22:6n3. Both 12- and 15-LO activities were recovered mainly in the microsomal plus cytosolic fraction. In addition to monohydroxy products, epoxy, hydroxy derivatives were formed from 22:6n3 by the pineal. The major isomer was identified as 12-hydroxy-13,14-epoxy-22:5n3.

Animals↗

Rare case with metastatic involvement of hypothalamo-pituitary and pineal body presenting as hypopituitarism and diabetes insipidus.

An unusual case with metastatic spread of a small oat cell lung carcinoma to the hypothalamo-pituitary region and pineal body presenting as pituitary insufficiency is reported. Computed tomographic scan revealed an isodense mass in the hypothalamo-pituitary region and pineal body that was strongly enhanced by contrast medium. Magnetic resonance imaging demonstrated a downward displacement of the posterior lobe of the pituitary by the hypothalamo-pituitary mass. Dynamic assessment of hypothalamo-pituitary function showed hypopituitarism and diabetes insipidus; partial recovery was observed with the improvement in the carcinoma by chemotherapy. The brain was subsequently irradiated. The patient survived 10 months.

Aged↗

A newly designed method for removal of the pineal body, and depression of convulsions and enhancement of exploratory movements by pinealectomy in mice.

We designed a simple technique for surgical excision of the pineal body in mice. Such can be accomplished in 10 min by a skilled worker and there are no lesions whatever. In pinealectomized El-strain mice the appearance of convulsions was inhibited up to 30 days, while intact El-mice were all fallen into convulsions by being shaken up and down on a flat carton. Pentazole-induced convulsions propagate from one dd-mouse to another in an aggregated state, but such propagation did not occur in pinealectomized animals. Exploratory movements of pinealectomized dd-mice increased as compared to intact animals and the increase was always more extensively observed in El-mice in which, even in the intact animals, the exploratory movements were much more than those of dd-mice. From the above-mentioned experiment, it is considered that the pineal body plays a role not only in initiating but also in propagating convulsions, and that it may have a depressive action on motor activities in mice.

Animals↗

Circadian rhythm of glucose utilization in the pineal body of rats of different ages.

Employing quantitative autoradiography, pineal body glucose utilization (GU) was measured in daytime or at night in prepubertal (aged 1 month), adult (aged 3 months), and mature (over 12 months old) rats. In prepubertal and adult rats, in daytime, GU values within the pineal tissue were homogeneously distributed around 65 mumol glucose/100 g per min. In prepubertal animals no significant variations in GU were observed between daytime and nocturnal measurements. A circadian metabolic rhythmicity was evident in adult rats, with a GU peak measured at 2 a.m. In mature animals, GU also varied between day and night, with an increment in the relative difference between the two values. The present investigation is the first to demonstrate that circadian metabolic rhythmicity is absent before sexual maturation while it is enhanced in 12-month-old rats. These changes in pineal energy metabolism with advancing age are intriguing in view of the concept that the pineal gland may be involved in functional changes occurring during the process of aging.

Animals↗

Ultracytochemical localisation and comparison of adenyl cyclase activities in pineal bodies of Wistar rats and Mongolian gerbils.

In the pineal bodies of Wistar rats and mongolian gerbils (Meriones unguiculati) the main concentration of adenyl cyclase was found in capillary endothelial cells, their basal laminae, pericapillary amorphous material and in nerve endings. In the intercellular clefts between the rat pineal cells there was no adenyl cyclase activity, but a considerable amount of this enzyme was detected in the gerbils. The adenyl cyclase lacks completely in the pinealocyte cytoplasms of both species. It was concluded that the gerbil pineal cells may be more reactive to various hormonal influence than those of the rat.

Adenylyl Cyclases↗

Pineal body metastasis.

We present a rare case of a pineal body metastasis developed from an oat cell carcinoma of the lung. Diagnosis by CT brain scan was easy but could have been difficult if the metastasis was solitary with the primary focus of tumor unknown. This lesion was temporarily radiosensitive but non-responsive to cytotoxic drugs and the patient died after other metastases developed.

Brain Neoplasms↗

Malignant melanotic neuroectodermal tumor arising from the pineal body.

A case of a melanotic neuroectodermal tumor arising from pineal region of a 4-year-old girl is presented. The tumor had spread diffusely to the meninges, consistent with malignant behavior. Histologically, the tumor consisted primarily of epithelial elements arranged in tubules, cords and nests separated by fibrous vascular tissue in addition to a small neuroblastomatous focus. Melanin pigment was frequently observed in the epithelial tumor cells, and melanin-laden macrophages were also often observed. No teratoid elements were found. Immunohistochemically, tumor cells were positive for neuron-specific enolase but were nonreactive for S-100 protein, epithelial membrane antigen, glial fibrillary acidic protein, vimentin, alpha-fetoprotein and human chorionic gonadotrophin. Ultrastructurally, the epithelial nature of the tumor cells could be easily demonstrated. In addition, melanosomes in various stages in maturation were observed, indicating melanogenesis of the tumor. On the basis of the tumor location and the histological similarities previously observed for the fetal pineal body, it is very likely that this melanotic epithelial tumor could have originated from the fetal pineal gland.

Brain Neoplasms↗

The pineal body and pinealectomy in the cotton rat, Sigmodon hispidus.

The pineal body is known to be an important component in the regulation of seasonal reproduction. The gross morphology of the rodent pineal gland is highly variable and this variability may be related to the degree of its involvement in regulating reproduction. The size and complexity of the pineal gland of the cotton rat appear to be well correlated with the known reproductive responses of this species to photoperiod. The cotton rat pineal is a large (2,500 micrometer X 500 micrometer) mass originating from the dorsal diencephalon and extending dorsally to the superior sagittal sinus. The cotton rat pineal is solid and cannot be divided into deep and superficial portions as in some rodents. Animals obtained from the field were found to survive conventional pinealectomy when it was carried out under methoxyflurane anesthesia. These results indicate that the cotton rat could be used as a wild animal model for pineal gland-seasonal reproduction research.

Animals↗

Scanning electron microscopic study of the freeze-fractured pineal body of the rat.

The three-dimensional ultrastructure of the pineal body of the rat is described on the basis of freeze-fractured preparations. The pineal capsule consists of irregular cells with very flat and perforated processes. Through these openings, extremely branched canaliculi, extending to almost every pineal cell, communicate with the tissue compartment outside the organ. The pericapillary spaces contain, in juxtaposition with capillaries of the fenestrated type, nerve fibers as well as a flocculent granular and filamentous material of unknown origin and chemical nature.

Animals↗

The pineal body of the dog.

A technique is described for finding the pineal body of the dog. The posterior half of the skull is cut a little behind the parietofrontal suture, through the occipital condyles. The cerebral hemispheres and cerebellum are carefully sliced, disclosing the pineal at the frontal edge of the colliculi. Two types of cells are present, those with completely round nuclei, and others with vesicular and variably shaped nuclei. In the histological pattern, ependymal cells were observed on the edges, pinealocytes and glial cells within the gland.

Animals↗

Circadian profile of Per gene mRNA expression in the suprachiasmatic nucleus, paraventricular nucleus, and pineal body of aged rats.

Aging alters circadian components such as the free-running period, the day-to-night activity ratio and photic entrainment in behavioral rhythms, and 2-deoxyglucose uptakes and neuronal firing in the suprachiasmatic nucleus (SCN). A core clock mechanism in the mouse SCN appears to involve a transcriptional feedback loop in which Period (Per) and Cryptochrome (Cry) genes play a role in negative feedback. The circadian rhythm systems include photic entrainment, clock oscillation, and outputs of clock information such as melatonin production. In this experiment, we examined clock gene expression to determine whether circadian input, oscillation, and output are disrupted with aging. Circadian expression profiles of rPer1, rPer2, or rCry1 mRNA were very similar in the SCN, the paraventricular nucleus of the hypothalamus (PVN), and the pineal body of young and aged (22-26 months) rats. On the other hand, the photic stimulation-induced rapid expression of Per1 and Per2 in the SCN was reduced with aging. The present results suggest that the molecular mechanism of clock oscillation in the SCN, PVN, and pineal body is preserved against aging, whereas the impairment of Per1 induction in the SCN after light stimulation may result in impaired behavioral photic entrainment in aged rats.

Aging↗

Metastatic small cell carcinoma to the pineal body: case report.

A case of metastatic small cell carcinoma to the pineal body is reported and the clinical and radiological features of this rare tumor are discussed. A 66-year-old man presented with progressive dementia, gait disturbance, vertical gaze palsy, and convergence retraction nystagmus. Computed tomographic scan revealed a 2 X 3-cm high-density mass in the pineal region, which showed strong contrast enhancement. The tumor was resected through a right occipital transtentorial approach. The pathological diagnosis of the surgical specimens was small cell carcinoma. A systemic workup for the primary lesion subsequently revealed small cell carcinoma of the lung. Although occurring rarely, metastatic tumor should be considered in the differential diagnosis of pineal tumor in elderly patients.

Aged↗

[Effect of pineal body extract on cytoxan-induced leucopenia in mice].

The effect of pig pineal extract on cytoxan-induced leucopenia in mice was studied. Three preparations of pineal body, Songlesu A, B and C, were used. All of them were effective in leucopenia. They delayed the time of the lowest white count, reduced the extent of white cell reduction and elevated and sustained the white count for several days despite the continuation of cytoxan injection. The effect of Songlesu A was most marked. The differences between the white count of group A (Songlesu A plus cytoxan) and the control (cytoxan plus normal saline) are very significant (P less than 0.01) in a period of 8-15 days after giving the drugs. After discontinuation of medication, the recovery of group A was better than that in the control group also very significantly (P less than 0.01). It is evident that Songlesu A is most worthy of further investigation. However, the effect of Songlesu A was no longer marked from the seventeenth day when the white count started to decline. This is most probably due to the severe bone marrow damage by the large dose of cytoxan accumulated or the protracted daily administration. Moreover, Songlesu A may sensitize the bone marrow to cytoxan toxicity or change the rate of recovery after bone marrow damage.

Animals↗

[Circadian variations in the incorporation of gamma-aminobutyric acid (GABA) and tritiated taurine into the pineal body of CD mice].

Pineal uptake of two putative neurotransmitters, gamma-aminobutyric acid (GABA) and taurine, was investigated during the 24 h-cycle in mice kept in long (14L/10D) or short (10L/14D) photoperiods. Tritiated mediators were intraperitoneally injected and their concentration both in pineal gland and cerebellum were measured at several times along the nycthemere. A circadian rhythm of exogenous GABA uptake was observed in mice kept in long photoperiods: GABA uptake was high during the night, when the gland was active and low during the day. It corresponded to the pineal cycle of indoleamine synthesis. It was particularly sensitive to sudden changes of lighting. In short photoperiods, a similar cycle was observed but the result was not significant because of individual variations. Taurine uptake did not show such a circadian rhythm either in long or in short photoperiods: it was constant and rather low with large variations from one animal to another.

Animals↗

Effects of irradiation on the sensitivity of melatonin release to norepinephrine in cultured pineal bodies of rats.

We measured levels of basal and norepinephrine (NE) -induced melatonin release in cultured pineal bodies of rats just after and 2 days after irradiation (20 or 200 Gy) or sham-irradiation. On the day of irradiation, basal and NE-induced melatonin release were not affected by irradiation. Two days after irradiation, basal melatonin levels in both irradiated groups were significantly lower than those in control group, whereas NE-induced melatonin levels in the irradiated groups were higher than those in the control group. These results suggested that irradiation decreases basal melatonin synthesis in pineal glands but that melatonin response to NE is increased after irradiation.

Adrenergic alpha-Agonists↗