• Asian-Australasian Journal of Animal Sciences
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• v.30 no.12
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• pp.1784-1795
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• 2017

Objective: The study examined the effect of intravenous administration of bacterial endotoxin-lipopolysaccharide (LPS) -on the nocturnal secretion of melatonin and on the expression of enzymes of the melatonin biosynthetic pathway in the pineal gland of ewes, taking into account two different photoperiodic conditions: short-night (SN; n = 12) and long-night (LN; n = 12). Methods: In both experiments, animals (n = 12) were randomly divided into two groups: control (n = 6) and LPS-treated (n = 6) one. Two hours after sunset, animals received an injection of LPS or saline. Blood samples were collected starting one hour after sunset and continuing for 3 hours after the treatment. The ewes were euthanized 3 hours after LPS/saline treatment. The concentration of hormones in plasma was assayed by radioimmunoassay. In the pineal gland, the content of serotonin and its metabolite was determined by HPLC; whereas the expression of examined genes and protein was assayed using real-time polymerase chain reaction and Western Blot, respectively. Results: Endotoxin administration lowered (p<0.05) levels of circulating melatonin in animals from LN photoperiod only during the first hour after treatment, while in ewes from SN photoperiod only in the third hour after the injection. Inflammation more substantially suppressed biosynthesis of melatonin in ewes from SN photoperiod, which were also characterised by lower (p<0.05) cortisol concentrations after LPS treatment compared with animals from LN photoperiod. In the pineal gland of ewes subjected to SN photoperiod, LPS reduced (p<0.05) serotonin content and the expression of melatonin biosynthetic pathway enzymes, such as tryptophan hydroxylase and arylalkylamine-N-acetyltransferase. Pineal activity may be disturbed by circulating LPS and proinflammatory cytokines because the expression of mRNAs encoding their corresponding receptors was determined in this gland. Conclusion: The present study showed that peripheral inflammation reduces the secretion of melatonin, but this effect may be influenced by the photoperiod.

• Development and Reproduction
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• v.5 no.1
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• pp.1-8
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• 2001

Golden hamsters show the reproductive activity that is determined by the photoperiod (length of light per day). Photoperiod is an environmental factor that is predictable through an entire year. The hamsters are sexually active in summer during which day length exceeds night time. The critical length is at least 12.5 hours of light in a day where reproductive function is maintained. The information of photoperiod is mediated by the pineal gland because removal of pineal gland blocks the influence of photoperiod on reproductive activity. The hamsters without pineal gland maintain sexual activity and promote it in a situation that suppresses gonadal activity. The pineal gland secretes melatonin that reflects the photoperiod. The appropriate administrations of melatonin into both pineal intact and pinealectomized hamsters lead to a gonadal reression. The results suggest that melatonin constitutes a part of control mechanism whereby environmental information is transduced to neuroendocrine signal respensible for the functional integrity of the reproductive system. Despite of the intense studies, the action site of melatonin is on the whole unknown. It is mainly due to the lack of acute efffct of melatonin on the secretion of reproductive hormones. However, sexually regressed animals display the low levelsof gonadotropins and the augmentation of the hypothalamic gonadotropin-releasing hormone (GnRH) content, implying that the antigonadotropic effects either by photoperiod and/or by the treatment of melatonin are mediated by the GnRH neuronal system. The action mechanism by which melatonin exerts its effect on GnRH neuron needs to be investigated. Recent cloning of melatonin receptor will contribute to examine various and putative potencies of melatonin via its anatomical identification and the action mechanism of melatonin on target tissues at the molecular level.

• Development and Reproduction
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• v.14 no.3
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• pp.185-197
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• 2010

The reproduction of animals is a means to maintain their species. The golden hamsters are seasonal breeders, and their reproduction is regulated by the photoperiod. The shifts of the sexual functions imply the changes of the protein expression, and those are reflected by the proteome. Thus the present study was to examine via two dimensional polyacrylamide gel electrophoresis (2d PAGE), the physiological changes and the alterations of protein expressions in hypothalamus upon the reproductive situation related to the pineal gland. Among the pineal intact animals, the reproductive functions were sustained in animals housed in long photoperiod (LP) but regressed in animals housed in short photoperiod. And those pinealectomized animals showed high sexual activities regardless of photoperiod. Ultimately they were branched into dichotomy, sexually active and inactive animals. Apart from the changes of physiological parameters upon the reproductive conditions, there were obvious differences in proteins extracted from the hypothalamus. The hypothalamus of LP animals presented high levels of enzymes which are involved in the production of energy, glycolysis and Krebs cycle. The increased energy might be related to the GnRH synthesis in hypothalamus and indirectly to the constant cell divisions in spermatogenesis. Taken together, the impacts of the photoperiodic information controlling reproduction could be observed through 2d PAGE. Therefore, the present results suggest the potential of biomarkers collectively to diagnose the fertility and the infertility by way of proteomics in organs with regard to the reproductive system, further could be applied to diagnose various diseases.

• Proceedings of the Korean Journal of Food and Nutrition Conference
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• 2000.05a
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• pp.13-20
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• 2000

Melatonin, a chemical mediator produced in the mammalian pineal gland and several other organ, is a ubiquitously acting antioxidant. It has been shown to scavenge the hydroxyl radical (ㆍOH), singlet oxygen ($^1$O$_2$) and the peroxynitrite anion (ONOO-). In addition, melatonin reportedly stimulates a number of antioxidative enzymes including glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase. Antioxidative effect of melatonin in pharmacological and physiological level was investigated using hepatocarcinogen 2-nitropropane (2-NP) and pinealectornized (Px) rats, respectively. Lipid peroxidation (LPO) as indicated by malondialdehyde and 4-hydroxyalkenals and DNA damage as indicated by 8-hydroxydeoxyguanosine (8-OH-dG) induced by 2-NP were prevented by melatonin. The degree of LPO and DNA damage in Px rats were higher than those of intact old and young ones suggesting the removal of pineal gland resulted in higher accumulation of oxidative damage.

• Development and Reproduction
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• v.16 no.1
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• pp.1-8
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• 2012

The reproduction of animals is a way to maintain their species and demands a large amount of energy. The golden hamsters are seasonal breeders whose reproductive activities are regulated by photoperiod (length of day time in a day). The photic information received is transported to the pineal gland via many steps. Melatonin produced by the pineal gland affects the reproductive neuroendocrine system to manage reproductive activities. The major regulator neurons, secreting gonadotropin-releasing hormone, integrate all kinds of information to govern the reproductive frame hypothalamuspituitary-gonad axis. The elements impinging on the neurons are recently outspread. Thus the present review is to briefly survey the elements discovered newly and subjected to the active research realm and their correlations, focusing on the regulation of reproduction in mainly male golden hamsters as a representative animal.

• Anatomy and Cell Biology
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• v.56 no.1
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• pp.32-38
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• 2023

The Galenic venous system plays a vital role in the drainage of blood from deeper parts of the brain. This venous system is contributed by many major veins. These veins are located closer to the pineal gland making the surgical approach in this region difficult. Any accidental injury or occlusion of the vein of Galen could lead to devasting results. Thus, studying the dimensions of the vein of Galen is more important. Hence, we aimed to evaluate the morphometry and trajectory to the vein of Galen. About 100 computed tomographic venography records were evaluated and the length, diameter of vein of Galen, angle between straight sinus and vein of Galen and distance from internal occipital protuberance and roof of fourth ventricle to vein of Galen were studied. The mean length and diameter of vein of Galen were 9.8±2.7 and 4.08±1.04 respectively. The mean angle between straight sinus and vein of Galen was 64.2°. The mean distance between external occipital protuberance and roof of fourth ventricle to vein of Galen were 52±6.9 and 33.3±4.5 respectively. No significant morphometric differences were observed between the age groups as well as between the sexs. The results obtained from this study may be helpful for the neurosurgeons in better understanding of the anatomy of the Galenic venous system and to adopt a safe surgical approach to improve the efficacy of the surgeries of the pineal gland and also in the region of vein of Galen.

• Journal of Life Science
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• v.23 no.8
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• pp.1064-1072
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• 2013

Circadian rhythm is controlled by hormonal oscillations governing the physiology of all living organisms. In mammals, the main function of the pineal gland is to transform the circadian rhythm generated in the hypothalamic suprachiasmatic nucleus into rhythmic signals of circulating melatonin characterized by a largely nocturnal increase that closely reflects the duration of night time. The pineal gland has lost direct photosensitivity, but responds to light via multi-synaptic pathways that include a subset of retinal ganglion cells. Rhythmic control is achieved through a tight coupling between environmental lighting and arylalkylamine-N-acetyltransferase (AANAT) expression, which is the rhythm-controlling enzyme in melatonin synthesis. Previous studies on the nocturnal expression of AANAT protein have described transcriptional, post-transcriptional, and post-translational regulatory mechanisms. Molecular mechanisms for dependent AANAT expression provide novel aspects for melatonin's circadian rhythmicity. Extensive animal research has linked pineal melatonin for the expression of seasonal rhythmicity in many mammalian species to the modulation of circadian rhythms and to sleep regulation. It has value in treating various circadian rhythm disorders, such as jet lag or shift-work sleep disorders. Melatonin, also, in a broad range of effects with a significant regulation influences many of the body's physiological functions. In addition, this hormone is known to influence reproductive, cardiovascular, and immunological regulation as well as psychiatric disorders.

• Radiation Oncology Journal
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• v.20 no.2
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• pp.100-107
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• 2002

Purpose : The aim of this retrospective study was to assess the treatment results of 30 patients with pineal region tumors who were underwent radiation therapy under the diagnosis by either CT or MRI. There was no histological verification. We analyzed the prognostic factors that have a significant effect on the overall survival (OS) and disease free survival (DFS) rates. Materials and Methods : A total 30 patients with pineal region tumors were treated between March 1983 and August 1995. After a trial radiation therapy of $20\~30\;Gy/2\~3$ weeks, the patients were evaluated for their clinical response and radiological response by either CT or MRI and the final treatment direction was then decided. According to their response to the trial radiation therapy and the involved site, radiation treatment was given in various fields i.e., local, ventricle, whole brain and craniospinal field. The radiation dose ranged from 40.8 to 59.4 Gy (Median 50.4 Gy). The median follow up was 36.5 months $(4\~172\;months)$. Results : An improvement or stability in the clinical symptoms was observed in 28 patients $(93.3\%)$ after the trial RT. Nineteen patients $(63.3\%)$ showed a partial or complete response by CT or MRI. The two-year and five-year survival rates of the patients were $66.7\%$ and $55.1\%$, respectively. No significant difference in the survival rates according to the degree of the radiological response was abserved after the trial RT. The results of univariate analysis showed that age, the primary site, the performance status $(KPS\geq70)$, the degree of response after completing RT and the RT field were significant prognostic factors affecting the survival and disease free survival rates (p<0.05). Conclusion : The clinical and histological characteristics of pineal region tumors are quite complex and diverse. Therefore, it is difficult to predict the histological diagnosis and the possibility of radiocurability only with the initial response to RT. We think that the development of less invasive histological diagnostic techniques and tailored treatment to the histological type of each tumor are needed.

• Journal of Embryo Transfer
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• v.24 no.4
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• pp.237-247
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• 2009

Melatonin (N-acetyl-5-methoxytryptamine) is the major neurohormone secreted during the night by the vertebrate pineal gland. The circadian pattern of pineal melatonin secretion is related to the biological clock within the suprachiasmatic nucleus (SCN) of the hypothalamus in mammals. The SCN coordinates the body's rhythms to the environmental light-dark cycle in response to light perceived by the retina, which acts mainly on retinal ganglion cells that contain the photopigment melanopsin. Calbindin-D9k (CaBP-9k) is a member of the S100 family of intracellular calcium- binding proteins, and in this review, we discuss the involvement of melatonin and CaBP-9k with respect to calcium homeostasis and apoptotic cell death. In future studies, we hope to provide important information on the roles played by CaBP-9k in cell signal transduction, cell proliferation, and $Ca^{2+}$ homeostasis in vivo and in vitro.

• The Korean Journal of Zoology
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• v.39 no.4
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• pp.337-351
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• 1996

Melatonin Is a multifunctional hormone secreted from the pineal gland in the middle of cerebrum and cerebellum. Its synthesis and release reflect photopedod;Photopedod is a yearly predictable ambient factor that most animals utilize as an environmental cue for maximum survival. Hamsters maintaln reproductive activity in summer during which day length exceeds night time. Upon the advent of autumnal equinox they undergo gonadal regression. The photoperiodic effects are prevented by removal of the pineal gland and restored by the timed repiacument of melatonin. The results suggest that melatonin constitutes part of control mechanism whereby environmental information is transduced to neuroendocrine signal responsIble for the functional integrity of the reproductive system. From the studies for the action site of melatonin following the treatment of photopedod or melatonin in the lesion of a spedflc portion of hypothalamus, suprachiasmatic nuclei and pars tuberalis are shown to be a consensus site for melatonIn. The action of melatonin. In the regulation of reproduction is largely unknown. It is mainly due to the lack of acute effect of melatonin on gonadotropin secretion. However, reduction of the gonadotropln release and augmentation of the hypothalamic gonadotropin-releasing hormone (GnRH) content by long-term treatment of melatonln Indicate that constant presence of melatonln may partidpate in the regulation of sexual activity via the GnRH neuronal system. The action mechanism by which melatonin exerts Its effect on GnRH neuron needs to be eluddated. The inability of opiold analogues to affect the reproductive hormones in sexually regressed animals by inhibftory photopedod and melatonin suggests that the opioldergic neuron may be a prime intervening mediator. Recent cloning of melatonin receptor will contribute to investigate its anatomical Identification and the action mechanism of melatonin on target tissues at the molecular level.