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Pineal Gland Abstracts: 1998

Note: the following is a limited selection of abstracts available at PubMed, Science Direct, and Toxnet.

http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9593645&dopt=Abstract

Gen Comp Endocrinol 1998 Jun;110(3):237-51

Stress-reactive response of the gerbil pineal gland: concretion genesis.

Milin J.

Medical Faculty, Institute of Pathology and Histology, Novi Sad, Serbia, Yugoslavia.

The reaction of pinealocytes and glia cells to an acute immobilization stress and their poststress recovery was studied in gerbils. Pinealocytes responded to immobilization with an increased peptidergic activity and formation of new concretions, whereas glia cells with an increased growth of interstitial concretions. The occurrence of degenerating pinealocytes indicated deleterious actions of immobilization stress on functionally stimulated cells. The pyroantimonate method to detect Ca2+ demonstrated enlarged crystalline profiles (Ca2+ crystallization into hydroxyapatite) in functionally stimulated pinealocytes and the accumulation of Ca2+ in the interstitial concretion. The pinealocyte concretions did not show the Ca2+ accumulation. The pineal gland poststress recovery was manifested by a reduced functionally stimulated pinealocyte activity and a protracted increase in glia cell activity. It is suggested that the physiological relevance of the crystallization of Ca2+ into hydroxyapatite is to maintain a noradrenalin-stimulated Ca2+ influx at an optimal level during attentuated pinealocyte turnover. The interstitial concretions may lower the extracellular Ca2+ concentrations and thereby stimulate pinealocytes and restrict an increased Ca2+ influx. Copyright 1998 Academic Press.

PMID: 9593645 [PubMed - indexed for MEDLINE]

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11248993&dopt=Abstract

Comp Biochem Physiol A Mol Integr Physiol 1998 Feb;119(2):493-501

Potential protective effects of melatonin on bone marrow of rats exposed to cytotoxic drugs.

Anwar MM, Mahfouz HA, Sayed AS.

Department of Physiology, Faculty of Medicine, Assiut University, Egypt.

Myelosuppression is the most serious, dose limiting, toxicity of cytotoxic drugs. Efforts to protect the bone marrow have been only variably successful, and no agreement exists on how to approach this problem. Melatonin, the major hormonal product of the pineal gland, is supposed to have both chemoprotective and myelostimulatory effects. This experimental study was carried out to test these two effects on the bone marrow of rats, daily intraperitoneally injected with 100 microg melatonin. Injection of 10 mg aracytin for 10 days produced a significant (P < 0.01) decrease in red blood cells count (RBCs), total leucocytic count, as well as platelets count. When melatonin was injected along with aracytin, it would significantly increase (P < 0.05) RBC count and (P < 0.01) blood platelet count. Injection of melatonin after aracytin treatment would significantly increase (P < 0.01) RBC, total leucocytic and platelet counts in comparison with rats treated with aracytin only. The effects of melatonin were more clear in rats treated with it after aracytin injection than those treated with melatonin and aracytin at the same time. Furthermore, it was found that aracytin produced a significant (P < 0.01) decrease in serum total proteins, albumin, and significantly increased the (P < 0.01) albumin/globulin ratio. Melatonin injection would significantly increase (P < 0.01) total protein, globulin, and significantly decrease (P < 0.01) the albumin/glubulin ratio when injected either with aracytin or after aracytin treatment. These results indicate that melatonin protects bone marrow, lymphoid tissues from damaging effect of cytotoxic drugs, as well as stimulating the suppressed bone marrow.

PMID: 11248993 [PubMed - indexed for MEDLINE]

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9885994&dopt=Abstract

J Pineal Res 1998 Dec;25(4):245-50

Effect of estrogen on melatonin synthesis in female peripubertal rats as related to adenylate cyclase activity.

Okatani Y, Hayashi K, Sagara Y.

Department of Obstetrics and Gynecology, Kochi Medical School, Japan.

To determine the mechanism for the modulatory effect of estrogen on melatonin synthesis, we evaluated the effects of estrogen on the activity of adenylate cyclase in female Sprague-Dawley rats of peripubertal age. Adenylate cyclase activity was measured in homogenates of pineal glands from rats aged 3 and 10 weeks in the mid-dark and in the mid-light. Ovariectomy was performed and a subcutaneous injection of estradiol benzoate (E2B) was administered daily starting at the age of 6 weeks. A peak in adenylate cyclase activity in the pineal gland was observed in untreated (control) rats with intact ovaries at 4 weeks. Ovariectomy at week 6 led to significant increases in the activity of adenylate cyclase at week 8. At week 10, adenylate cyclase activity resembled that of control animals. The subcutaneous injection of E2B (1.0 microg/day) suppressed the increase in adenylate cyclase activity induced by ovariectomy, similar to the level seen in control rats with intact ovaries. The changes in the mid-light activity of pineal adenylate cyclase resembled that seen at the mid-dark with the value being significantly lower than that observed in the mid-dark. Such changes in the mid-dark activity of adenylate cyclase resembled those observed with N-acetyltransferase (NAT) at the same time, as previously described. Results suggest that estrogen modulates adenylate cyclase activity in the pineal gland of peripubertal female rats. The decline in melatonin synthesis during puberty may be related to an increase in estrogen level. The inhibitory effect of estrogen on melatonin synthesis appeared to be mediated by a change in the norepinephrine-induced stimulation of pineal adenylate cyclase activity.

PMID: 9885994 [PubMed - indexed for MEDLINE]

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9885988&dopt=Abstract

J Pineal Res 1998 Dec;25(4):193-200

The impact of photoperiods and melatonin on gonadal development in juvenile Turkish hamsters (Mesocricetus brandti).

Gunduz B, Stetson MH.

Department of Biological Sciences, University of Delaware, Newark 19716, USA.

The reproductive response of both intact adult and juvenile Turkish hamsters has been thoroughly studied and shown to be similar, unlike the golden hamster where juveniles remain aphotoperiodic until approximately 8 weeks of age. Unstudied to date, however, is the role of the pineal and its hormone melatonin in generating the testicular response to photoperiod in juvenile Turkish hamsters. Therefore, in this study we examined the reproductive response of prepubertal male Turkish hamsters, subjected to four different photoperiods (8L:16D, 16L:8D, 20L:4D, and 24L:0D) with altered pineal gland function. At 15 days of age, long-day-born (16L:8D) hamsters were either pinealectomized, received melatonin implants, or remained untreated. Testes sizes were measured every 2 weeks. Testicular growth occurred only in untreated and beeswax implanted groups in 16L:8D. Exposure to other photoperiods inhibited testicular development in untreated and beeswax implanted animals. Removal of the pineal gland, masking of the daily melatonin rhythm with constant release subcutaneous melatonin implants, or eliminating the daily rhythm of melatonin by continuous light exposure resulted in inhibition of gonadal development. These results demonstrate that juvenile Turkish hamsters respond similarly to adults on all photoperiods and under all conditions of pineal function tested.

PMID: 9885988 [PubMed - indexed for MEDLINE]

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9718719&dopt=Abstract

J Photochem Photobiol B 1998 Jun 1;43(3):186-92

The photoperiod transducer melatonin and the immune-hematopoietic system.

Maestroni GJ.

Center for Experimental Pathology, Instituto Cantonale di Patologia, Locarno, Switzerland. icpcps@guest.cscs.ch

The pineal neurohormone melatonin functionally synchronizes the organism with the photoperiod. It is now well recognized that melatonin also plays an important immunoregulatory role. T-helper cells bear G-protein coupled melatonin cell-membrane receptors and, perhaps, melatonin nuclear receptors. Activation of melatonin receptors enhances the release of T-helper cell type 1 (Th1) cytokines, such as gamma-interferon and interleukin-2, as well as of novel opioid cytokines which crossreact immunologically with both interleukin-4 and dynorphin B. Melatonin has also been reported to enhance the production of interleukin-6 from human monocytes. These mediators may counteract secondary immunodeficiencies, protect mice against lethal viral and bacterial diseases, synergize with interleukin-2 in cancer patients and influence hematopoiesis. Hematopoiesis is apparently influenced by the action of the melatonin-induced opioids on kappa-opioid receptors present on stromal bone marrow cells. Most interestingly, gamma-interferon and colony stimulating factors may modulate the production of melatonin in the pineal gland. A hypothetical pineal-immune-hematopoietic network is, therefore, taking shape. From the immunopharmacological point of view, a call is made for clinical studies on the effect of melatonin in viral disease including human immunodeficiency virus-infected patients and cancer patients. In conclusion, melatonin seems to be an important immunomodulatory hormone which deserves to be further studied to identify its relevance in immune-based diseases, its therapeutic indications, and its adverse effects.

Publication Types:

• Review
• Review, Tutorial

PMID: 9718719 [PubMed - indexed for MEDLINE]

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From Toxnet:

Teratology 1998 Mar;57(3):21A

A case of brain tumor.

Watanabe O, Oya N, Tanemura M, Matsubara H, Suzuki Y, Kajiura S, Okada S, Suzumori K

Department of Obstetrics and Gynecology, Nagoya City University Medical School, Nagoya, Aichi, Japan.

Abstract: Intracranial tumor of fetus is very rare. The incidence of brain tumors is 0.34 per million live birth. It was reported that the prognosis in many cases was very poor. The patient's mother was a 25-year-old primiparous woman, who visited our hospital at 19 weeks of gestation. The tumor, which was a mixture of cystic and solid parts, was detected in the fetal cranium on ultrasonography. The tumor size enlarged with the advancing pregnancy. Biparietal diameter at 28 weeks of gestation measured 84 mm. Most of the normal brain was occupied with the brain tumor. The intestine was also detected in the fetal thoracic cavity with hydroamnion. The infant girl (1,746 g, Apgar score 1) was delivered by cesarean section at 29 weeks of gestation because of a ruptured membrane and large amount of genital bleeding. She was diagnosed as partial placenta previa at the operation. Although the infant was immediately transferred to the NICU, she died. In autopsy, a clear polycystic tumor, about 10 x 5 cm, was located on the subtentrial area. Histological examination revealed it to be composed of bone, cartilage, fat, nerve, etc., and subsequently diagnosed as immature teratoma of brain tumor of pineal origin. In addition, there were right microphthalmia and eventration of diaphragm with immaturity of the lung. In prenatal diagnosis of neoplasm in the central nerve system, ultrasonography was useful.

Note from FAN:
Definition of microphthalmia: An unnatural smallness of the eyes, occurring as the result of disease or of imperfect development.

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9476656&dopt=Abstract

Histol Histopathol 1998 Jan;13(1):271-4

Is hematopoiesis under the influence of neural and neuroendocrine mechanisms?

Maestroni GJ.

Centre for Experimental Pathology, Istituto Cantonale di Patologia, Locarno, Switzerland.

It is well recognized that the immune response is under the influence of a variety of neural or neuroendocrine mechanisms. Much less studied is the possible influence of these mechanisms on hematopoiesis. Here I review the existing evidence about a neural and/or neuroendocrine regulation of hematopoiesis. The physiology of the blood forming system seems to be controlled at three levels, i.e. at the cellular level by the bone marrow stroma, at the humoral level by hematopoietic cytokines and finally by catecholamines and neuroendocrine factors. Bone marrow catecholamines originate from sympathetic nerve fibers and from hematopoietic cells directly. Catecholamines of neural origin show a circadian rhythmicity. Adrenoceptors present on bone marrow cells include the alpha 1-subtype which seems to mediate the catecholaminergic control of hematopoiesis. Neuroendocrine factors including substance P, neurokinin-A and the pineal hormone melatonin might also influence hematopoiesis by affecting hematopoietic cytokines. In particular, melatonin seems to affect hematopoiesis via the induction in bone marrow T-helper cells of two novel opioid cytokines. A complete understanding of the neural and neuroendocrine regulation of hematopoiesis might provide new conceptual and therapeutic perspectives in a variety of hematopoietic and immune diseases.

Publication Types:

• Review
• Review, Tutorial

PMID: 9476656 [PubMed - indexed for MEDLINE]

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11281954&dopt=Abstract

Int J Neuropsychopharmcol 1998 Dec;1(2):115-120

Subsensitive melatonin suppression by dim white light: possible biological marker of panic disorder.

Nathan PJ, Burrows GD, Norman TR.

Brain Sciences Institute, Swinburne University of Technology, Victoria, Australia.

Light is involved in providing entrainment of circadian rhythms and the suppression of the pineal hormone melatonin. In patients with affective disorders, there have been indications of circadian as well as seasonal variation in illness, which may be reflected in melatonin production. Varying sensitivity to light has been noted within healthy individuals as well as in some patients with affective disorders. Recent evidence suggests that patients with panic disorder may have an altered and phase-delayed melatonin rhythm. The present study examined the nocturnal plasma melatonin rhythm in patients with panic disorder, and also examined their melatonin sensitivity to dim light. The melatonin rhythm was examined in 6 patients with panic disorder and 8 controls. The melatonin sensitivity to dim white light (200 lx) was examined in 8 patients with panic disorder and 63 controls and was compared to that of a group of 7 patients with other anxiety disorders. Patients with panic disorder demonstrated a trend towards higher and delayed peak melatonin levels compared to controls. Patients with panic disorder also had a subsensitive melatonin suppression by dim white light, compared to controls and patients with other anxiety disorders (p<0.005). The phase-delayed circadian rhythm observed in patients with panic disorder may be secondary to the subsensitivity of the melatonin response to light. It is hypothesized that the subsensitivity may be due to abnormal neurotransmitter/receptor systems involved in regulation of melatonin suppression and circadian rhythmicity, and may lead to phase- delayed circadian rhythms. The melatonin subsensitivity to light may be used as a biological marker of panic disorder.

PMID: 11281954 [PubMed - as supplied by publisher]

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11249007&dopt=Abstract

Comp Biochem Physiol A Mol Integr Physiol 1998 Feb;119(2):593-8

Vitamin A deficiency reduces the responsiveness of pineal gland to light in Japanese quail (Coturnix japonica).

Fu Z, Kato H, Sugahara K, Kubo T.

Faculty of Agriculture, Utsunomiya University, Japan.

Synthesis of melatonin in pineal gland is under the control of light environment. The recent finding of the presence of rhodopsin-like photopigment (pinopsin) and retinal in the avian pinealocytes has led to a hypothesis that vitamin A is involved in photoresponses of the pineal gland. We have thus analyzed the effect of vitamin A deficiency on the regulatory system of melatonin synthesis in the pineal gland of Japanese quail. Depletion of vitamin A from Japanese quails was attained by feeding them with a vitamin A-free diet supplemented with retinoic acid. In the vitamin A-deficient birds, diurnal rhythm in melatonin production persisted such that the phase of the wave was similar to that seen in the control birds. However, the amplitude of the nighttime surge of pineal melatonin was damped by vitamin A deficiency. When the control birds were briefly exposed to light at night, pineal melatonin dropped to the daytime level. In contrast, only slight decrease was observed in the vitamin A-deficient quails. The light responsiveness was restored after feeding the vitamin A-deficient quails with the control diet for 1 week. These results indicate that vitamin A plays essential roles in maintaining sufficient responsiveness of the avian pineal gland to photic input.

PMID: 11249007 [PubMed - indexed for MEDLINE]

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10904532&dopt=Abstract

Biocell 1998 Aug;22(2):123-40

The brain of the armadillo Dasypus hybridus. A general view of its most salient features.

Ferrari CC, Aldana Marcos HJ, Carmanchahi PD, Benitez I, Affanni JM.

Instituto de Neurociencia (INEUCI-CONICET), Facultad de Ciencias Exactas y Naturales, Ciudad Universitaria, Pab. II, Buenos Aires, Argentina. carina@biolo.bg.fcen.uba.ar

The most salient neuroanatomical features of the brain of the seven banded armadillo Dasypus hybridus are described. The microscopic characteristics were studied by serial transverse and sagittal paraffin sections, stained with Nissl and Kluver-Barrera technique. This analysis comprises the telencephalon, diencephalon and mesencephalon. The most outstanding features of this brain are:
1) Great development of rhinencephalic structures (olfactory bulbs, olfactory tubercles, anterior commissure and pyriform cortex).
2) The relative size of the induseum griseum strongly suggests that this animal would be useful for a variety of studies on this structure.
3) The high position of the rhinal fissure on the lateral hemispheric wall determines the smallness of neocortex. Therefore, this armadillo is also useful for decortication studies.
4) Absence of a distinct pineal organ.
5) Conspicuous subfornical and subcommissural organs.
6) Absence of a distinct intermediate lobe in the hypophysis.

PMID: 10904532 [PubMed - indexed for MEDLINE]

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10437151&dopt=Abstract

Zhongguo Yao Li Xue Bao 1998 Nov;19(6):575-81

Suppression of oxygen toxicity by melatonin.

Reiter RJ, Tan DX, Qi WB.

Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio 78284-7762, USA. Reiter@uthscsa.edu

Melatonin, the chief secretory product of the pineal gland, was recently found to be a free radical scavenger and antioxidant. While most studies to date have used pharmacological quantities of melatonin to limit oxidative damage, physiologic concentrations of the indole which are present in aerobic organisms have also been shown to resist molecular damage inflicted by free radicals. Melatonin has several functions in terms of its antioxidative ability. It readily scavenges the most highly toxic free radical, the hydroxyl radical, and it directly detoxifies the peroxynitrite anion, nitric oxide, singlet oxygen, and the peroxyl radical. Precisely how efficient melatonin is in neutralizing each of these toxic agents remains to be determined. Melatonin also may stimulate several antioxidative enzymes including superoxide dismutase, glutathione peroxidase, and glutathione reductase as well as inhibiting the pro-oxidative enzyme, nitric-oxide synthase. Finally, melatonin chelates transition metal ions and prevents the deterioration of cellular membranes. This combination of actions may all contribute to melatonin's ability to reduce oxidative damage. Melatonin is highly effective in reducing nuclear DNA damage and membrane lipid destruction due to toxic free radicals in vivo. These findings have implications for disease processes, eg, neurodegenerative and cardiovascular diseases, which involve free radicals and for aging itself, which also is believed to be related to accumulated oxidative damage.

Publication Types:

• Review
• Review, Tutorial

PMID: 10437151 [PubMed - indexed for MEDLINE]

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10374414&dopt=Abstract

Chin Med J (Engl) 1998 Mar;111(3):197-203

Melatonin: a chemical photoperiodic signal with clinical significance in humans.

Pang SF, Pang CS, Poon AM, Lee PP, Liu ZM, Shiu SY.

Department of Physiology, University of Hong Kong, China.

Secretion of pineal melatonin exhibits a diumal rhythm and a seasonal rhythm in humans. Night-time melatonin is high at 3-5 year-old and decreases with age. Many drugs and pathological conditions also change melatonin levels in the circulation. Melatonin has a mild sedative effect and has been used effectively in synchronizing the sleep-wake cycle of patients with sleep disorders. Immunoenhancing, anti-cancer, anti-aging and anti-oxidant effects of melatonin have been proposed. Recent studies suggest that melatonin receptors are present in central and peripheral tissues. The importance of melatonin receptors on the nervous, reproductive, immune and renal functions is implicated. Studies on the molecular biology, physiology and pathology of melatonin receptors in different tissues are progressing rapidly. The physiological and pathological changes in melatonin secretion, multifarious melatonin actions, and diverse melatonin receptors reported suggest that melatonin is a photoperiodic signal with clinical significance in humans.

Publication Types:

• Review
• Review, Tutorial

PMID: 10374414 [PubMed - indexed for MEDLINE]

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10322644&dopt=Abstract

Chin Med J (Engl) 1998 Jan;111(1):7-11

No Abstract available

Cross-talk between the pineal gland and immune system.

Poon AM, Liu ZM, Pang SF.

Department of Physiology, Faculty of Medicine, University of Hong Kong, China.

Publication Types:

• Review
• Review, Tutorial

PMID: 10322644 [PubMed - indexed for MEDLINE]

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10074800&dopt=Abstract

Prog Brain Res 1998;119:365-82

The suprachiasmatic nucleus-paraventricular nucleus interactions: a bridge to the neuroendocrine and autonomic nervous system.

Buijs RM, Hermes MH, Kalsbeek A.

Netherlands Institute for Brain Research, Amsterdam, The Netherlands. r.buijs@nih.knaw.nl

Vasopressin (VP) is one of the principal neurotransmitters of the suprachiasmatic nucleus (SCN). By means of anatomical, physiological and electrophysiological techniques we have demonstrated that VP containing pathways from the SCN serve to affect neuroendocrine and 'autonomic' neurons in the paraventricular nucleus. By direct and indirect connections VP serves to inhibit corticosterone secretion, not only by affecting ACTH secretion but also by controlling the adrenal cortex via a neuronal route. Apart from controlling the pineal and adrenal, we also observed that the SCN is able to influence the heart. Subjecting rats or humans to light affects heart rate in a dose-dependent manner. These results suggest an important role for the SCN and VP in the SCN in the regulation of neuroendocrine and autonomic functions.

Publication Types:

• Review
• Review, Tutorial

PMID: 10074800 [PubMed - indexed for MEDLINE]

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9885993&dopt=Abstract

J Pineal Res 1998 Dec;25(4):240-4

Chronic exposure to 2.9 mT, 40 Hz magnetic field reduces melatonin concentrations in humans.

Karasek M, Woldanska-Okonska M, Czernicki J, Zylinska K, Swietoslawski J.

Laboratory of Electron Microscopy, Medical University of Lodz, Poland. Micha.7497401@pharmanet.com.pl

Diurnal rhythm of serum melatonin concentrations was estimated in 12 men with low back pain syndrome before and after exposure to a very low-frequency magnetic field (2.9 mT, 40 Hz, square wave, bipolar). Patients were exposed to the magnetic field for 3 weeks (20 min per day, 5 days per week) either in the morning (at 10:00 hr) or in the late afternoon (at 18:00 hr). Significant depression in nocturnal melatonin rise was observed regardless of the time of exposure. This phenomenon was characteristic for all the subjects, although the percent of inhibition of melatonin secretion varied among the studied individuals.

PMID: 9885993 [PubMed - indexed for MEDLINE]

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9865485&dopt=Abstract

Toxicology 1998 Sep 15;130(2-3):183-90

2-Nitropropane-induced lipid peroxidation: antitoxic effects of melatonin.

Kim SJ, Reiter RJ, Rouvier Garay MV, Qi W, El-Sokkary GH, Tan DX.

Department of Cellular and Structural Biology, The University of Texas Health Science Center, San Antonio 78284-7762, USA.

The degree of lipid peroxidation (LPO) as indicated by the levels of thiobarbituric acid reactive substances, malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA), and the activity of sorbitol dehydrogenase (SDH) in serum as parameters of hepatotoxicity were studied in rats treated with a single intraperitoneal (i.p.) injection of the hepatocarcinogen 2-nitropropane (2-NP). Since melatonin, the main secretory product of the pineal gland, has been shown to protect against a number of toxic agents, it was given 30 min before 2-NP to test its protective effect against 2-NP toxicity. Significant increases in LPO in liver (P<0.0001), lung (P<0.05) and kidney (P<0.0001) were observed 24 h after 4 mmol/kg 2-NP while serum SDH activity was increased 470-fold. All parameters showed time (0, 4, 8, 24 h) and dose (0, 1, 2, 3, 4 mmol/kg) dependency. The induction of LPO by 2-NP was significantly reduced in lung and kidney when melatonin (2.5, 5 or 10 mg/kg) was given prior to 2-NP administration. The elevation in serum SDH caused by 2-NP was also reduced when melatonin was given. These findings show that 2-NP induces LPO and that pharmacological levels of melatonin can reduce the toxicity of this hepatocarcinogen.

PMID: 9865485 [PubMed - indexed for MEDLINE]

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9861610&dopt=Abstract

Neurosci Biobehav Rev 1998;23(1):1-4

The Cartesian clock metaphor for pineal gland operation pervades the origin of modern chronobiology.

Barrera-Mera B, Barrera-Calva E.

Dpto. de Fisiologia, Facultad de Medicina UNAM, Mexico, D.F., Mexico.

In theoretical descriptions formulated during the 1600s, R. Descartes attributed a clock-like role to the pineal gland. He established the belief that pineal function underlies the laws of the universe that determine the cyclic sleep-awake states in man. Recent reports about pineal circadian pacemakers now validate the brilliant accuracy of Cartesian thought, in relation to the relevant role of the pineal gland.

Publication Types:

• Review
• Review, Tutorial

PMID: 9861610 [PubMed - indexed for MEDLINE]

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http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9852259&dopt=Abstract

Int J Mol Med 1998 Mar;1(3):539-43

The role of melatonin in the human fetus (review).

Thomas L, Drew JE, Abramovich DR, Williams LM.

Molecular Neuroendocrinology Unit, The Rowett Research Institute, Bucksburn, Aberdeen AB21 9EJ, Scotland, UK.

Melatonin, an indole amine, primarily derived from the pineal gland is secreted during the hours of darkness. Melatonin acts as a hormonal transduction of photoperiod influencing the timing of seasonal and daily (circadian) physiological rhythms. Maternal melatonin crosses the placenta and enters the fetal circulation providing photoperiodic information to the fetus influencing the subsequent circadian and seasonal rhythms of the offspring. The function of melatonin in humans is more obscure. However, melatonin has attained prominence as a treatment for disturbed circadian rhythms and sleep patterns which occur as a result of transmeridian travel, shift work or blindness. The biological clock, the hypothalamic suprachiasmatic nuclei (SCN), possesses melatonin receptors, in both the adult and fetal human. This concurs with the reported influence of melatonin on human circadian rhythmicity and indicates that this influence may begin in utero. Melatonin receptors are widespread in the human fetus and occur in both central and peripheral tissue from early in fetal development. Thus, the influence of melatonin on the developing human fetus may not be limited to entraining circadian rhythmicity. Considering the transplacental availability of melatonin to the fetus the ingestion of melatonin by pregnant women may be inadvisable.

Publication Types:

• Review
• Review, Tutorial

PMID: 9852259 [PubMed - indexed for MEDLINE]

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