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Recent studies (Alaou-Ismaili et al. 2020; Kilic et al. Eur J Radiol 56:212–219, 2005) among experienced sub-specialized neurosurgeons described divergent perceptions of surgical risk for venous sacrifice in posterior fossa surgery. Three galenic veins stood out as controversial in venous risk assessment and underexplored in the literature: the internal occipital vein (IOV), the precentral cerebellar vein (PCV), and the superior vermian vein (SVV). We have conducted a narrative review based on a systematic literature search to analyze terminology and anatomic descriptions and to suggest a coherent synthesis of published data on these veins. A systematic PubMed literature search was carried out using the keywords: “posterior fossa,” “venous anatomy,” and “radiology.” Relevant radiological, microsurgical, and anatomical articles were selected if they described the anatomy of the three veins. Anatomical descriptions were analyzed with hermeneutic methodology alongside the articles’ radiological and anatomical dissection pictures. New illustrations were created to depict the synthesized image of the venous anatomy. A total of 13 articles described the anatomy and terminology of the relevant veins. The descriptions of the IOV included smaller non-occipital vessels that confused the identification of the vessel. IOV is analyzed to be the vein draining the primary visual cortex, which drains into the vein of Galen (VG). The PCV and SVV enter the VG from below and are fused in almost half of all studied patients, creating a third vessel by the name of the superior cerebellar vein. A conscientious narrative review and hermeneutic analysis produced a synthesized, uniform picture of terminology and anatomy. Consensus on anatomical descriptions and definitions are indispensable for validation of anatomy, research into anatomical variation, for surgical planning and documentation.

Surgical experience in pineal surgery is largely confined to a few experienced surgeons and may be lost when they stop their practice. The objective of this study is to systematically preserve and analyze valuable practical knowledge of pineal region surgical venous anatomy. A survey was constructed to obtain experienced surgeons’ perception of estimated risks and individual experience following occlusion of veins during pineal surgery. Data were qualitative and analyzed with a mixed methods approach. Of the 126 invited neurosurgeons, 40 submitted completed questionnaires. General agreement existed of which veins were associated with high and low risks following occlusion. The risk of death was estimated to be high with sacrifice of the vein of Galen (83%), both internal cerebral veins (69%) and the basal veins (58%). The risk of death was estimated to be lower with the sacrifice of both superior vermian veins (13%) and one internal occipital vein (10%). Importantly, a sub-group of experienced surgeons reported substantial risk of death and consequences with the sacrifice of cerebellar bridging veins (8–13%). Our findings provide a coherent picture of surgical risk with venous sacrifice, which can inform the surgical community of systematically gathered views from aggregated surgeries of a very large cohort of patients. Extensive presurgical radiological workup and anatomical studies seemed to correlate more cautious risk estimations. Our findings increase available knowledge of risks of venous complications.

Many physiological systems rely on hormones to communicate and time cellular and tissue-level functions. Most endocrine systems are dynamic and governed by complex regulatory systems and/or feedback mechanisms to generate precise patterns and modes of hormone release in order to optimize control of physiological and cellular processes. This Special Issue focuses on hormone release patterns (ultradian, infradian, pulsatile, circadian), with a special emphasis on the hypothalamic-pituitary axis as well as melatonin release, and how these patterns of hormone secretion change during life stages and disease.

Many physiological systems rely on hormones to communicate and time cellular and tissue-level functions. Most endocrine systems are dynamic and governed by complex regulatory systems and/or feedback mechanisms to generate precise patterns and modes of hormone release in order to optimize control of physiological and cellular processes. This Special Issue focuses on hormone release patterns (ultradian, infradian, pulsatile, circadian), with a special emphasis on the hypothalamic-pituitary axis as well as melatonin release, and how these patterns of hormone secretion change during life stages and disease.

Many physiological systems rely on hormones to communicate and time cellular and tissue-level functions. Most endocrine systems are dynamic and governed by complex regulatory systems and/or feedback mechanisms to generate precise patterns and modes of hormone release in order to optimize control of physiological and cellular processes. This Special Issue focuses on hormone release patterns (ultradian, infradian, pulsatile, circadian), with a special emphasis on the hypothalamic-pituitary axis as well as melatonin release, and how these patterns of hormone secretion change during life stages and disease.

The investigation of pineal-specific proteins is not new but offers scope for identification of antigonadotropic compound(s). There is difference in the activities of the reproductively active and inactive phase pineal homogenates of seasonally breeding animals, e.g., squirrels. The present study aimed at checking the squirrel pineal proteins adopting gel-electrophoresis technique. Homogenate of the reproductively quiescent phase pineal homogenate separated into 14 fractions whereas that of reproductively active phase pineal presented 17 protein fractions (3 additional fractions). It is assumed that these three protein bands (which were not noted for the squirrel in reproductively inactive phase) are responsible for the antigonadal/ antigonadotropic effect of the pineal gland. The present study, though very preliminary in nature, has brought out the difference in the pattern of proteins of two different phases of the pineal gland- reproductively active and quiescent. The data throw open scope for extensive biochemical studies to decipher the physical and chemical nature and the properties of an anti-gonadotropic protein.

The investigation of pineal-specific proteins is not new but offers scope for identification of antigonadotropic compound(s). There is difference in the activities of the reproductively active and inactive phase pineal homogenates of seasonally breeding animals, e.g., squirrels. The present study aimed at checking the squirrel pineal proteins adopting gel-electrophoresis technique. Homogenate of the reproductively quiescent phase pineal homogenate separated into 14 fractions whereas that of reproductively active phase pineal presented 17 protein fractions (3 additional fractions). It is assumed that these three protein bands (which were not noted for the squirrel in reproductively inactive phase) are responsible for the antigonadal/ antigonadotropic effect of the pineal gland. The present study, though very preliminary in nature, has brought out the difference in the pattern of proteins of two different phases of the pineal gland- reproductively active and quiescent. The data throw open scope for extensive biochemical studies to decipher the physical and chemical nature and the properties of an anti-gonadotropic protein.

The investigation of pineal-specific proteins is not new but offers scope for identification of antigonadotropic compound(s). There is difference in the activities of the reproductively active and inactive phase pineal homogenates of seasonally breeding animals, e.g., squirrels. The present study aimed at checking the squirrel pineal proteins adopting gel-electrophoresis technique. Homogenate of the reproductively quiescent phase pineal homogenate separated into 14 fractions whereas that of reproductively active phase pineal presented 17 protein fractions (3 additional fractions). It is assumed that these three protein bands (which were not noted for the squirrel in reproductively inactive phase) are responsible for the antigonadal/ antigonadotropic effect of the pineal gland. The present study, though very preliminary in nature, has brought out the difference in the pattern of proteins of two different phases of the pineal gland- reproductively active and quiescent. The data throw open scope for extensive biochemical studies to decipher the physical and chemical nature and the properties of an anti-gonadotropic protein.

The investigation of pineal-specific proteins is not new but offers scope for identification of antigonadotropic compound(s). There is difference in the activities of the reproductively active and inactive phase pineal homogenates of seasonally breeding animals, e.g., squirrels. The present study aimed at checking the squirrel pineal proteins adopting gel-electrophoresis technique. Homogenate of the reproductively quiescent phase pineal homogenate separated into 14 fractions whereas that of reproductively active phase pineal presented 17 protein fractions (3 additional fractions). It is assumed that these three protein bands (which were not noted for the squirrel in reproductively inactive phase) are responsible for the antigonadal/ antigonadotropic effect of the pineal gland. The present study, though very preliminary in nature, has brought out the difference in the pattern of proteins of two different phases of the pineal gland- reproductively active and quiescent. The data throw open scope for extensive biochemical studies to decipher the physical and chemical nature and the properties of an anti-gonadotropic protein.

The pineal gland is an important component of the multioscillatory avian circadian timekeeping system. The other principal clock components reside in the retinae of the eyes and the hypothalamus. The best known output signal from the pineal gland is melatonin, which is a lipophilic molecule. The presence of melatonin is however not limited to the organisms having a pineal gland. Melatonin is present from plants to protozoa to humans. Melatonin seems to have been evolutionarily conserved as an adaptive molecule of darkness of the daily day-night environment. In birds, the major physiological roles of pineal melatonin are in its involvement in the daily and seasonal timekeeping as well as photoperiodic time measurement. Birds use daily rhythm in melatonin secretion to decode the time-of-day as well as the time-of-year information. Besides, melatonin performs other physiological roles, namely in the immune function, free radical scavenging, etc. Avian pineal (melatonin) directly regulates several circadian behaviors, but intriguingly not the circadian rhythm-mediated photoperiodic induction of gonadal development. Melatonin, however, may act as an endocrine modulator of seasonal reproduction. In this article, we describe briefly the avian timekeeping system and then discuss the potential roles of pineal gland and melatonin in daily and seasonal timing of physiology in birds, particularly in songbirds.

The pineal gland is an important component of the multioscillatory avian circadian timekeeping system. The other principal clock components reside in the retinae of the eyes and the hypothalamus. The best known output signal from the pineal gland is melatonin, which is a lipophilic molecule. The presence of melatonin is however not limited to the organisms having a pineal gland. Melatonin is present from plants to protozoa to humans. Melatonin seems to have been evolutionarily conserved as an adaptive molecule of darkness of the daily day-night environment. In birds, the major physiological roles of pineal melatonin are in its involvement in the daily and seasonal timekeeping as well as photoperiodic time measurement. Birds use daily rhythm in melatonin secretion to decode the time-of-day as well as the time-of-year information. Besides, melatonin performs other physiological roles, namely in the immune function, free radical scavenging, etc. Avian pineal (melatonin) directly regulates several circadian behaviors, but intriguingly not the circadian rhythm-mediated photoperiodic induction of gonadal development. Melatonin, however, may act as an endocrine modulator of seasonal reproduction. In this article, we describe briefly the avian timekeeping system and then discuss the potential roles of pineal gland and melatonin in daily and seasonal timing of physiology in birds, particularly in songbirds.

The pineal gland is an important component of the multioscillatory avian circadian timekeeping system. The other principal clock components reside in the retinae of the eyes and the hypothalamus. The best known output signal from the pineal gland is melatonin, which is a lipophilic molecule. The presence of melatonin is however not limited to the organisms having a pineal gland. Melatonin is present from plants to protozoa to humans. Melatonin seems to have been evolutionarily conserved as an adaptive molecule of darkness of the daily day-night environment. In birds, the major physiological roles of pineal melatonin are in its involvement in the daily and seasonal timekeeping as well as photoperiodic time measurement. Birds use daily rhythm in melatonin secretion to decode the time-of-day as well as the time-of-year information. Besides, melatonin performs other physiological roles, namely in the immune function, free radical scavenging, etc. Avian pineal (melatonin) directly regulates several circadian behaviors, but intriguingly not the circadian rhythm-mediated photoperiodic induction of gonadal development. Melatonin, however, may act as an endocrine modulator of seasonal reproduction. In this article, we describe briefly the avian timekeeping system and then discuss the potential roles of pineal gland and melatonin in daily and seasonal timing of physiology in birds, particularly in songbirds.

The pineal gland is an important component of the multioscillatory avian circadian timekeeping system. The other principal clock components reside in the retinae of the eyes and the hypothalamus. The best known output signal from the pineal gland is melatonin, which is a lipophilic molecule. The presence of melatonin is however not limited to the organisms having a pineal gland. Melatonin is present from plants to protozoa to humans. Melatonin seems to have been evolutionarily conserved as an adaptive molecule of darkness of the daily day-night environment. In birds, the major physiological roles of pineal melatonin are in its involvement in the daily and seasonal timekeeping as well as photoperiodic time measurement. Birds use daily rhythm in melatonin secretion to decode the time-of-day as well as the time-of-year information. Besides, melatonin performs other physiological roles, namely in the immune function, free radical scavenging, etc. Avian pineal (melatonin) directly regulates several circadian behaviors, but intriguingly not the circadian rhythm-mediated photoperiodic induction of gonadal development. Melatonin, however, may act as an endocrine modulator of seasonal reproduction. In this article, we describe briefly the avian timekeeping system and then discuss the potential roles of pineal gland and melatonin in daily and seasonal timing of physiology in birds, particularly in songbirds.

The pineal gland is an important component of the multioscillatory avian circadian timekeeping system. The other principal clock components reside in the retinae of the eyes and the hypothalamus. The best known output signal from the pineal gland is melatonin, which is a lipophilic molecule. The presence of melatonin is however not limited to the organisms having a pineal gland. Melatonin is present from plants to protozoa to humans. Melatonin seems to have been evolutionarily conserved as an adaptive molecule of darkness of the daily day-night environment. In birds, the major physiological roles of pineal melatonin are in its involvement in the daily and seasonal timekeeping as well as photoperiodic time measurement. Birds use daily rhythm in melatonin secretion to decode the time-of-day as well as the time-of-year information. Besides, melatonin performs other physiological roles, namely in the immune function, free radical scavenging, etc. Avian pineal (melatonin) directly regulates several circadian behaviors, but intriguingly not the circadian rhythm-mediated photoperiodic induction of gonadal development. Melatonin, however, may act as an endocrine modulator of seasonal reproduction. In this article, we describe briefly the avian timekeeping system and then discuss the potential roles of pineal gland and melatonin in daily and seasonal timing of physiology in birds, particularly in songbirds.

The pineal gland produces the hormone melatonin, and its volume may influence melatonin levels. We describe an innovative method for estimating pineal volume in humans and present the association of pineal parenchyma volume with levels of the primary melatonin metabolite, 6-sulfatoxymelatonin. We selected a random sample of 122 older Icelandic men nested within the AGES-Reykjavik cohort and measured their total pineal volume, their parenchyma volume, and the extent of calcification and cysts. For volume estimations we used manual segmentation of magnetic resonance images in the axial plane with simultaneous side-by-side view of the sagittal and coronal plane. We used multivariable adjusted linear regression models to estimate the association of pineal parenchyma volume and baseline characteristics, including 6-sulfatoxymelatonin levels. We used logistic regression to test for differences in first morning urinary 6-sulfatoxymelatonin levels among men with or without cystic or calcified glands. The pineal glands varied in volume, shape, and composition. Cysts were present in 59% of the glands and calcifications in 21%. The mean total pineal volume measured 207 mm(3) (range 65-536 mm(3)) and parenchyma volume 178 mm(3) (range 65-503 mm(3)). In multivariable-adjusted models, pineal parenchyma volume was positively correlated with 6-sulfatoxymelatonin levels (β = 0.52, p < 0.001). Levels of 6-sulfatoxymelatonin did not differ significantly by presence of cysts or calcification. By using an innovative method for pineal assessment, we found pineal parenchyma volume to be positively correlated with 6-sulfatoxymelatonin levels, in line with other recent studies., Funding Agencies:RANNIS (the Icelandic Research Fund)National Institutes on Aging Intramural Research Program N01-AG-12100Hjartavernd (the Icelandic Heart Association)Althingi (the Icelandic Parliament)Harvard Catalyst AwardNational Cancer Institute at the National Institutes of Health Training Grant NIH T32 CA09001Prostate Cancer Foundation

Nowadays, the effector capacity of melatonin in the immune system is indisputable. The almost ubiquitous distribution of melatonin receptors, its immune synthesis, and the effects of several immunological mediators on the melatonin production reinforce the concept of the melatonin/immune bidirectional circuit. Throughout the present chapter, we have highlighted that melatonin acts on the immune response by combined mechanisms which mainly involve the modulation of cytokines and the oxidative stress markers production. Overall, melatonin acts as an immune activator in basal or immunodepressed conditions, whereas it might exert a negative regulation under transient or chronic exacerbated immune response. Due to the variety of the melatonin immunomodulatory actions, it has been tested in extensive models. Thus, the clinical relevance of the several faces of melatonin on immune conditions such as infection, autoimmunity, vaccination, and immunosenescence as well as transplant and cancer is also reviewed.

Melatonin modulates a wide range of physiological functions with pleiotropic effects on the immune system. Despite the large number of reports implicating melatonin as an immunomodulatory compound, it still remains unclear how melatonin regulates immunity. While some authors argue that melatonin is an immunostimulant, many studies have also described anti-inflammatory properties. The data reviewed in this paper support the idea of melatonin as an immune buffer, acting as a stimulant under basal or immunosuppressive conditions or as an anti-inflammatory compound in the presence of exacerbated immune responses, such as acute inflammation. The clinical relevance of the multiple functions of melatonin under different immune conditions, such as infection, autoimmunity, vaccination and immunosenescence, is also reviewed. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Rosette-forming glioneuronal tumor (RGNT) of the fourth ventricle is a mixed glio-neuronal neoplasm recently codified by the World Health Organization WHO Classification of Central Nervous System (CNS) Tumors (2007). To date, 43 cases have been described in the literature; most occurring in the fourth ventricle region. We report the fourth case involving the pineal region in a 16-year-old female with signs of increased intracranial pressure (ICP). A stereotactic biopsy of the mass was followed by a debulking procedure. Both specimens revealed classic RGNT histology. The patient had stable scans 7 months post-resection. The clinical, radiological and histopathologic features of the previously described 43 cases are reviewed along with our illustrative case. Mean age of patients was 30 ± 12.8 years with 1.9:1 female to male ratio. The most common presenting signs related to increased ICP and posterior fossa involvement, including: headache (62.8%), ataxia (39.5%) and vomiting and vertigo (both 16.3%). This tumor usually presents with cystic changes (54.5%) with focal enhancement (60.9%) and hydrocephalus (43.2%). Microcalcifications and satellite lesions were common radiographic observations. All reported cases had the classic biphasic pattern. Rosenthal fibers and eosinophilic granular bodies are each present in approximately two thirds of cases. Ki-67 labeling index is consistently low (mean (%): 1.8 ± 0.75 SD). The isocitrate dehydrogenase 1 or 2 mutation found in low grade diffuse gliomas is not identified in this RGNT case. Reported outcome is nearly uniformly excellent after complete or subtotal resection. A solitary report of recurrence after 10 years and the limited experience with this entity suggest that long term follow up is advisable.

Rosette-forming glioneuronal tumor (RGNT) of the fourth ventricle is a mixed glio-neuronal neoplasm recently codified by the World Health Organization WHO Classification of Central Nervous System (CNS) Tumors (2007). To date, 43 cases have been described in the literature; most occurring in the fourth ventricle region. We report the fourth case involving the pineal region in a 16-year-old female with signs of increased intracranial pressure (ICP). A stereotactic biopsy of the mass was followed by a debulking procedure. Both specimens revealed classic RGNT histology. The patient had stable scans 7 months post-resection. The clinical, radiological and histopathologic features of the previously described 43 cases are reviewed along with our illustrative case. Mean age of patients was 30 ± 12.8 years with 1.9:1 female to male ratio. The most common presenting signs related to increased ICP and posterior fossa involvement, including: headache (62.8%), ataxia (39.5%) and vomiting and vertigo (both 16.3%). This tumor usually presents with cystic changes (54.5%) with focal enhancement (60.9%) and hydrocephalus (43.2%). Microcalcifications and satellite lesions were common radiographic observations. All reported cases had the classic biphasic pattern. Rosenthal fibers and eosinophilic granular bodies are each present in approximately two thirds of cases. Ki-67 labeling index is consistently low (mean (%): 1.8 ± 0.75 SD). The isocitrate dehydrogenase 1 or 2 mutation found in low grade diffuse gliomas is not identified in this RGNT case. Reported outcome is nearly uniformly excellent after complete or subtotal resection. A solitary report of recurrence after 10 years and the limited experience with this entity suggest that long term follow up is advisable.

Melatonin is currently proposed to be synthesized in non-photosensitive organs of vertebrates, besides its well-known sites of synthesis, the pineal gland and the retina. However, very few studies have demonstrated gene expression of MEL synthesizing enzymes in extrapineal and extraretinal locations. In the present study, present study focuses on the circadian expression of the two key enzymes of the melatoninergic pathway, the AANAT and the HIOMT in central and peripheral locations of the goldfish we give report of the full-length cloning of the two enzymes catalyzing the final steps of melatonin biosynthesis, the arylalkylamine N-acetyltransferase (AANAT) and the hydroxyindole-O-methyltransferase (HIOMT), in a teleosts fish, the goldfish (Carassius auratus). Both enzymes showed high similarity with other teleost sequences, corresponding to the goldfish AANAT-2 and HIOMT-2. Two forms of AANATs were widely known to exist in teleosts, but this is the first time that two isoforms of HIOMT are deduced from a phylogenetic analysis. Both enzymes were detected in several peripheral locations, including liver and gut, being present results the first to find HIOMT in non-photosensitive structures of a fish species. No studies exist on transcriptional regulation of the expression of MEL biosynthesis enzymes in non photosensitive structures in fish The daily expression pattern of both genes in pineal gland, retina, liver and gut was investigated using quantitative real time RT-PCR and cosinor analysis. This is the first time that a rhythmic expression of AANAT and HIOMT are found in digestive tissues of a vertebrate species, supporting a functional melatonin synthesis pathway in liver and gut of the goldfish. Besides, the transcriptional regulation of Aanat-2 in pineal and peripheral locations of goldfish maintained under different lighting conditions was investigated expression of gAANAT-2 is analyzed under different lighting conditions including continuous light and darknes

We have developed data demonstrating that the pineal gland, via its hormone melatonin, inhibits the proliferation of both human and animal models of breast cancer. As humans age there is the onset of disrupted sleep leading to a significant suppression in the nocturnal levels of melatonin after age 60. Based on these data we have hypothesized that the decline in pineal melatonin production, with the onset of old age, is a key factor in the age related increase in breast cancer. Using the Buffalo rat as a model, we have begun to characterize the melatonin rhythm in young, middle aged and old female rats. Our studies demonstrate that the nocturnal rise in both serum and pineal melatonin is significantly blunted in old rats compared to middle aged and young rats, and is blunted in middle aged rats compared to young rats. As well, uterine mtl melatonin receptor levels are greatly diminished in old female rats (by 80%) compared to young female rats. Finally, in our preliminary studies, tissue-isolated NMU-induced mammary tumors grew faster in young rats as compared to middle aged rats. However, tumors in middle aged rats are less responsive to the growth-suppressive actions of melatonin.

Reproduction in most fishes is discontinuous or seasonal. Rhythms with a periodicity of one year represent major components in the adaptation of concerned fish to their environment. Environmental factors, such as light and temperature, play an important role in the synchronization of this rhythmic activity of reproduction. In vertebrates, synchronization is mediated through the system which is composed of sensors and circadian oscillators like the pineal organ, the lateral eyes and the suprachiasmatic nuclei of the hypothalamus. The fish pineal seems to be involved in the timing and control of reproduction. On the basis of several experimental evidences, it is believed that the pineal is able to translate environmental information (photoperiod, temperature) into rhythmic messages. To date, two kinds of signals have been clearly identified, a nervous signal and a neurohormonal signal, i.e., melatonin. Whereas the functional significance of the nervous signal is not yet clearly understood, there is increasing evidence that in at least temperate zone vertebrates, melatonin is the chemical messenger of photoperiod (Zeitgeber). In contrast to the neuronal message, elaborated mainly (if not exclusively) by the pineal of ectotherms, melatonin appears to be a conservative signal in the vertebrate phylum. In all the species investigated so far, melatonin production is high during nighttime and low during daytime. Despite this apparent homogeneity, the involvement of the pineal in the temporal organization of reproduction, as well as the mechanisms by which the photic information is processed in the control of gonadal germ maturation in fish have been the matter of great interest. Molecular mechanism involved in photoreceptor-induced pathway in fish is yet to be known, without which benefit from such information remains unveiled.

Birds in general have not been frequently examined for the immunological influences of melatonin or pineal gland, as it has been potentially noted with the mammals including human being. There are only few reports suggesting that melatonin may play some role in the development and function of the immune system in the birds. The diurnal pattern of the melatonin synthesis is the same In almost all vertebrate groups so far examined, though differences exist in structure or anatomy of the pineal gland and seasonal variation in the peripheral melatonin level. Since functional relationship between neuroendocrine pineal gland and immune systems appears as to be diverse, it is logical that immunomodulatory effects of melatonin may be different in different seasons. The seasonal variation In melatonin level has been proved to improve the status of Immunity in seasonal tropical birds to bear the natural challenges. The level of peripheral melatonin minimizes some inflammatory diseases and sudden death syndrome in some poultry birds. The effect of melatonin also depends upon the phases of the inflammatory reaction/process. Pinealectomy in birds demonstrated functional interrelationship between the development of pineal gland, ontogeny of the melatonin secretion and immune system and/or neuroendocrine network. Bursectomy could influence the diurnal rhythm of melatonin and may abolish the effect of immunization on serum melatonin level. Specificities of avian immune system may be, however, very useful for understanding numerous phylogenetic and evolutionary mysteries. In this way a reciprocal functional connection between the avain immune system and the pineal gland seems to exist, but the mechanisms involved in maintaining the immune status by melatonin in avain group Is still not clear and needs to be elucidated.

Birds in general have not been frequently examined for the immunological influences of melatonin or pineal gland, as it has been potentially noted with the mammals including human being. There are only few reports suggesting that melatonin may play some role in the development and function of the immune system in the birds. The diurnal pattern of the melatonin synthesis is the same In almost all vertebrate groups so far examined, though differences exist in structure or anatomy of the pineal gland and seasonal variation in the peripheral melatonin level. Since functional relationship between neuroendocrine pineal gland and immune systems appears as to be diverse, it is logical that immunomodulatory effects of melatonin may be different in different seasons. The seasonal variation In melatonin level has been proved to improve the status of Immunity in seasonal tropical birds to bear the natural challenges. The level of peripheral melatonin minimizes some inflammatory diseases and sudden death syndrome in some poultry birds. The effect of melatonin also depends upon the phases of the inflammatory reaction/process. Pinealectomy in birds demonstrated functional interrelationship between the development of pineal gland, ontogeny of the melatonin secretion and immune system and/or neuroendocrine network. Bursectomy could influence the diurnal rhythm of melatonin and may abolish the effect of immunization on serum melatonin level. Specificities of avian immune system may be, however, very useful for understanding numerous phylogenetic and evolutionary mysteries. In this way a reciprocal functional connection between the avain immune system and the pineal gland seems to exist, but the mechanisms involved in maintaining the immune status by melatonin in avain group Is still not clear and needs to be elucidated.

Reproduction in most fishes is discontinuous or seasonal. Rhythms with a periodicity of one year represent major components in the adaptation of concerned fish to their environment. Environmental factors, such as light and temperature, play an important role in the synchronization of this rhythmic activity of reproduction. In vertebrates, synchronization is mediated through the system which is composed of sensors and circadian oscillators like the pineal organ, the lateral eyes and the suprachiasmatic nuclei of the hypothalamus. The fish pineal seems to be involved in the timing and control of reproduction. On the basis of several experimental evidences, it is believed that the pineal is able to translate environmental information (photoperiod, temperature) into rhythmic messages. To date, two kinds of signals have been clearly identified, a nervous signal and a neurohormonal signal, i.e., melatonin. Whereas the functional significance of the nervous signal is not yet clearly understood, there is increasing evidence that in at least temperate zone vertebrates, melatonin is the chemical messenger of photoperiod (Zeitgeber). In contrast to the neuronal message, elaborated mainly (if not exclusively) by the pineal of ectotherms, melatonin appears to be a conservative signal in the vertebrate phylum. In all the species investigated so far, melatonin production is high during nighttime and low during daytime. Despite this apparent homogeneity, the involvement of the pineal in the temporal organization of reproduction, as well as the mechanisms by which the photic information is processed in the control of gonadal germ maturation in fish have been the matter of great interest. Molecular mechanism involved in photoreceptor-induced pathway in fish is yet to be known, without which benefit from such information remains unveiled.

Reproduction in most fishes is discontinuous or seasonal. Rhythms with a periodicity of one year represent major components in the adaptation of concerned fish to their environment. Environmental factors, such as light and temperature, play an important role in the synchronization of this rhythmic activity of reproduction. In vertebrates, synchronization is mediated through the system which is composed of sensors and circadian oscillators like the pineal organ, the lateral eyes and the suprachiasmatic nuclei of the hypothalamus. The fish pineal seems to be involved in the timing and control of reproduction. On the basis of several experimental evidences, it is believed that the pineal is able to translate environmental information (photoperiod, temperature) into rhythmic messages. To date, two kinds of signals have been clearly identified, a nervous signal and a neurohormonal signal, i.e., melatonin. Whereas the functional significance of the nervous signal is not yet clearly understood, there is increasing evidence that in at least temperate zone vertebrates, melatonin is the chemical messenger of photoperiod (Zeitgeber). In contrast to the neuronal message, elaborated mainly (if not exclusively) by the pineal of ectotherms, melatonin appears to be a conservative signal in the vertebrate phylum. In all the species investigated so far, melatonin production is high during nighttime and low during daytime. Despite this apparent homogeneity, the involvement of the pineal in the temporal organization of reproduction, as well as the mechanisms by which the photic information is processed in the control of gonadal germ maturation in fish have been the matter of great interest. Molecular mechanism involved in photoreceptor-induced pathway in fish is yet to be known, without which benefit from such information remains unveiled.

Birds in general have not been frequently examined for the immunological influences of melatonin or pineal gland, as it has been potentially noted with the mammals including human being. There are only few reports suggesting that melatonin may play some role in the development and function of the immune system in the birds. The diurnal pattern of the melatonin synthesis is the same In almost all vertebrate groups so far examined, though differences exist in structure or anatomy of the pineal gland and seasonal variation in the peripheral melatonin level. Since functional relationship between neuroendocrine pineal gland and immune systems appears as to be diverse, it is logical that immunomodulatory effects of melatonin may be different in different seasons. The seasonal variation In melatonin level has been proved to improve the status of Immunity in seasonal tropical birds to bear the natural challenges. The level of peripheral melatonin minimizes some inflammatory diseases and sudden death syndrome in some poultry birds. The effect of melatonin also depends upon the phases of the inflammatory reaction/process. Pinealectomy in birds demonstrated functional interrelationship between the development of pineal gland, ontogeny of the melatonin secretion and immune system and/or neuroendocrine network. Bursectomy could influence the diurnal rhythm of melatonin and may abolish the effect of immunization on serum melatonin level. Specificities of avian immune system may be, however, very useful for understanding numerous phylogenetic and evolutionary mysteries. In this way a reciprocal functional connection between the avain immune system and the pineal gland seems to exist, but the mechanisms involved in maintaining the immune status by melatonin in avain group Is still not clear and needs to be elucidated.

Birds in general have not been frequently examined for the immunological influences of melatonin or pineal gland, as it has been potentially noted with the mammals including human being. There are only few reports suggesting that melatonin may play some role in the development and function of the immune system in the birds. The diurnal pattern of the melatonin synthesis is the same In almost all vertebrate groups so far examined, though differences exist in structure or anatomy of the pineal gland and seasonal variation in the peripheral melatonin level. Since functional relationship between neuroendocrine pineal gland and immune systems appears as to be diverse, it is logical that immunomodulatory effects of melatonin may be different in different seasons. The seasonal variation In melatonin level has been proved to improve the status of Immunity in seasonal tropical birds to bear the natural challenges. The level of peripheral melatonin minimizes some inflammatory diseases and sudden death syndrome in some poultry birds. The effect of melatonin also depends upon the phases of the inflammatory reaction/process. Pinealectomy in birds demonstrated functional interrelationship between the development of pineal gland, ontogeny of the melatonin secretion and immune system and/or neuroendocrine network. Bursectomy could influence the diurnal rhythm of melatonin and may abolish the effect of immunization on serum melatonin level. Specificities of avian immune system may be, however, very useful for understanding numerous phylogenetic and evolutionary mysteries. In this way a reciprocal functional connection between the avain immune system and the pineal gland seems to exist, but the mechanisms involved in maintaining the immune status by melatonin in avain group Is still not clear and needs to be elucidated.

Reproduction in most fishes is discontinuous or seasonal. Rhythms with a periodicity of one year represent major components in the adaptation of concerned fish to their environment. Environmental factors, such as light and temperature, play an important role in the synchronization of this rhythmic activity of reproduction. In vertebrates, synchronization is mediated through the system which is composed of sensors and circadian oscillators like the pineal organ, the lateral eyes and the suprachiasmatic nuclei of the hypothalamus. The fish pineal seems to be involved in the timing and control of reproduction. On the basis of several experimental evidences, it is believed that the pineal is able to translate environmental information (photoperiod, temperature) into rhythmic messages. To date, two kinds of signals have been clearly identified, a nervous signal and a neurohormonal signal, i.e., melatonin. Whereas the functional significance of the nervous signal is not yet clearly understood, there is increasing evidence that in at least temperate zone vertebrates, melatonin is the chemical messenger of photoperiod (Zeitgeber). In contrast to the neuronal message, elaborated mainly (if not exclusively) by the pineal of ectotherms, melatonin appears to be a conservative signal in the vertebrate phylum. In all the species investigated so far, melatonin production is high during nighttime and low during daytime. Despite this apparent homogeneity, the involvement of the pineal in the temporal organization of reproduction, as well as the mechanisms by which the photic information is processed in the control of gonadal germ maturation in fish have been the matter of great interest. Molecular mechanism involved in photoreceptor-induced pathway in fish is yet to be known, without which benefit from such information remains unveiled.

Birds in general have not been frequently examined for the immunological influences of melatonin or pineal gland, as it has been potentially noted with the mammals including human being. There are only few reports suggesting that melatonin may play some role in the development and function of the immune system in the birds. The diurnal pattern of the melatonin synthesis is the same In almost all vertebrate groups so far examined, though differences exist in structure or anatomy of the pineal gland and seasonal variation in the peripheral melatonin level. Since functional relationship between neuroendocrine pineal gland and immune systems appears as to be diverse, it is logical that immunomodulatory effects of melatonin may be different in different seasons. The seasonal variation In melatonin level has been proved to improve the status of Immunity in seasonal tropical birds to bear the natural challenges. The level of peripheral melatonin minimizes some inflammatory diseases and sudden death syndrome in some poultry birds. The effect of melatonin also depends upon the phases of the inflammatory reaction/process. Pinealectomy in birds demonstrated functional interrelationship between the development of pineal gland, ontogeny of the melatonin secretion and immune system and/or neuroendocrine network. Bursectomy could influence the diurnal rhythm of melatonin and may abolish the effect of immunization on serum melatonin level. Specificities of avian immune system may be, however, very useful for understanding numerous phylogenetic and evolutionary mysteries. In this way a reciprocal functional connection between the avain immune system and the pineal gland seems to exist, but the mechanisms involved in maintaining the immune status by melatonin in avain group Is still not clear and needs to be elucidated.

Reproduction in most fishes is discontinuous or seasonal. Rhythms with a periodicity of one year represent major components in the adaptation of concerned fish to their environment. Environmental factors, such as light and temperature, play an important role in the synchronization of this rhythmic activity of reproduction. In vertebrates, synchronization is mediated through the system which is composed of sensors and circadian oscillators like the pineal organ, the lateral eyes and the suprachiasmatic nuclei of the hypothalamus. The fish pineal seems to be involved in the timing and control of reproduction. On the basis of several experimental evidences, it is believed that the pineal is able to translate environmental information (photoperiod, temperature) into rhythmic messages. To date, two kinds of signals have been clearly identified, a nervous signal and a neurohormonal signal, i.e., melatonin. Whereas the functional significance of the nervous signal is not yet clearly understood, there is increasing evidence that in at least temperate zone vertebrates, melatonin is the chemical messenger of photoperiod (Zeitgeber). In contrast to the neuronal message, elaborated mainly (if not exclusively) by the pineal of ectotherms, melatonin appears to be a conservative signal in the vertebrate phylum. In all the species investigated so far, melatonin production is high during nighttime and low during daytime. Despite this apparent homogeneity, the involvement of the pineal in the temporal organization of reproduction, as well as the mechanisms by which the photic information is processed in the control of gonadal germ maturation in fish have been the matter of great interest. Molecular mechanism involved in photoreceptor-induced pathway in fish is yet to be known, without which benefit from such information remains unveiled.

Reproduction in most fishes is discontinuous or seasonal. Rhythms with a periodicity of one year represent major components in the adaptation of concerned fish to their environment. Environmental factors, such as light and temperature, play an important role in the synchronization of this rhythmic activity of reproduction. In vertebrates, synchronization is mediated through the system which is composed of sensors and circadian oscillators like the pineal organ, the lateral eyes and the suprachiasmatic nuclei of the hypothalamus. The fish pineal seems to be involved in the timing and control of reproduction. On the basis of several experimental evidences, it is believed that the pineal is able to translate environmental information (photoperiod, temperature) into rhythmic messages. To date, two kinds of signals have been clearly identified, a nervous signal and a neurohormonal signal, i.e., melatonin. Whereas the functional significance of the nervous signal is not yet clearly understood, there is increasing evidence that in at least temperate zone vertebrates, melatonin is the chemical messenger of photoperiod (Zeitgeber). In contrast to the neuronal message, elaborated mainly (if not exclusively) by the pineal of ectotherms, melatonin appears to be a conservative signal in the vertebrate phylum. In all the species investigated so far, melatonin production is high during nighttime and low during daytime. Despite this apparent homogeneity, the involvement of the pineal in the temporal organization of reproduction, as well as the mechanisms by which the photic information is processed in the control of gonadal germ maturation in fish have been the matter of great interest. Molecular mechanism involved in photoreceptor-induced pathway in fish is yet to be known, without which benefit from such information remains unveiled.

Birds in general have not been frequently examined for the immunological influences of melatonin or pineal gland, as it has been potentially noted with the mammals including human being. There are only few reports suggesting that melatonin may play some role in the development and function of the immune system in the birds. The diurnal pattern of the melatonin synthesis is the same In almost all vertebrate groups so far examined, though differences exist in structure or anatomy of the pineal gland and seasonal variation in the peripheral melatonin level. Since functional relationship between neuroendocrine pineal gland and immune systems appears as to be diverse, it is logical that immunomodulatory effects of melatonin may be different in different seasons. The seasonal variation In melatonin level has been proved to improve the status of Immunity in seasonal tropical birds to bear the natural challenges. The level of peripheral melatonin minimizes some inflammatory diseases and sudden death syndrome in some poultry birds. The effect of melatonin also depends upon the phases of the inflammatory reaction/process. Pinealectomy in birds demonstrated functional interrelationship between the development of pineal gland, ontogeny of the melatonin secretion and immune system and/or neuroendocrine network. Bursectomy could influence the diurnal rhythm of melatonin and may abolish the effect of immunization on serum melatonin level. Specificities of avian immune system may be, however, very useful for understanding numerous phylogenetic and evolutionary mysteries. In this way a reciprocal functional connection between the avain immune system and the pineal gland seems to exist, but the mechanisms involved in maintaining the immune status by melatonin in avain group Is still not clear and needs to be elucidated.

Reproduction in most fishes is discontinuous or seasonal. Rhythms with a periodicity of one year represent major components in the adaptation of concerned fish to their environment. Environmental factors, such as light and temperature, play an important role in the synchronization of this rhythmic activity of reproduction. In vertebrates, synchronization is mediated through the system which is composed of sensors and circadian oscillators like the pineal organ, the lateral eyes and the suprachiasmatic nuclei of the hypothalamus. The fish pineal seems to be involved in the timing and control of reproduction. On the basis of several experimental evidences, it is believed that the pineal is able to translate environmental information (photoperiod, temperature) into rhythmic messages. To date, two kinds of signals have been clearly identified, a nervous signal and a neurohormonal signal, i.e., melatonin. Whereas the functional significance of the nervous signal is not yet clearly understood, there is increasing evidence that in at least temperate zone vertebrates, melatonin is the chemical messenger of photoperiod (Zeitgeber). In contrast to the neuronal message, elaborated mainly (if not exclusively) by the pineal of ectotherms, melatonin appears to be a conservative signal in the vertebrate phylum. In all the species investigated so far, melatonin production is high during nighttime and low during daytime. Despite this apparent homogeneity, the involvement of the pineal in the temporal organization of reproduction, as well as the mechanisms by which the photic information is processed in the control of gonadal germ maturation in fish have been the matter of great interest. Molecular mechanism involved in photoreceptor-induced pathway in fish is yet to be known, without which benefit from such information remains unveiled.

Birds in general have not been frequently examined for the immunological influences of melatonin or pineal gland, as it has been potentially noted with the mammals including human being. There are only few reports suggesting that melatonin may play some role in the development and function of the immune system in the birds. The diurnal pattern of the melatonin synthesis is the same In almost all vertebrate groups so far examined, though differences exist in structure or anatomy of the pineal gland and seasonal variation in the peripheral melatonin level. Since functional relationship between neuroendocrine pineal gland and immune systems appears as to be diverse, it is logical that immunomodulatory effects of melatonin may be different in different seasons. The seasonal variation In melatonin level has been proved to improve the status of Immunity in seasonal tropical birds to bear the natural challenges. The level of peripheral melatonin minimizes some inflammatory diseases and sudden death syndrome in some poultry birds. The effect of melatonin also depends upon the phases of the inflammatory reaction/process. Pinealectomy in birds demonstrated functional interrelationship between the development of pineal gland, ontogeny of the melatonin secretion and immune system and/or neuroendocrine network. Bursectomy could influence the diurnal rhythm of melatonin and may abolish the effect of immunization on serum melatonin level. Specificities of avian immune system may be, however, very useful for understanding numerous phylogenetic and evolutionary mysteries. In this way a reciprocal functional connection between the avain immune system and the pineal gland seems to exist, but the mechanisms involved in maintaining the immune status by melatonin in avain group Is still not clear and needs to be elucidated.

A multi-center four-hourly sampling of many tissues for 7 days (00:00 on April 5-20:00 to April 11, 2004), on rats standardized for 1 month in two rooms on antiphasic lighting regimens happened to start on the day after the second extremum of a moderate double magnetic storm gauged by the planetary geomagnetic Kp index (which at each extremum reached 6.3 international [arbitrary] units) and by an equatorial index Dst falling to -112 and -81 nT, respectively, the latter on the first day of the sampling. Neuroendocrine chronomes (specifically circadian time structures) differed during magnetically affected and quiet days. The circadian melatonin rhythm had a lower MESOR and lower circadian amplitude and tended to advance in acrophase, while the MESOR and amplitude of the hypothalamic circadian melatonin rhythm were higher during the days with the storm. The circadian parameters of circulating corticosterone were more labile during the days including the storm than during the last three quiet days. Feedsidewards within the pineal-hypothalamic-adrenocortical network constitute a mechanism underlying physiological and probably also pathological associations of the brain and heart with magnetic storms. Investigators in many fields can gain from at least recording calendar dates in any publication so that freely available information on geomagnetic, solar and other physical environmental activity can be looked up. In planning studies and before starting, one may gain from consulting forecasts and the highly reliable nowcasts, respectively. © 2005 Elsevier SAS. All rights reserved.