The Role of the Melatoninergic System in Circadian and Seasonal Rhythms-Insights From Different Mouse Strains.

The melatoninergic system comprises the neurohormone melatonin and its molecular targets. The major source of melatonin is the pineal organ where melatonin is rhythmically produced during darkness. In mammals, melatonin biosynthesis is controlled by the central circadian rhythm generator in the suprachiasmatic nucleus (SCN) and photoreceptors in the retina. Melatonin elicits its function principally through two specific receptors called MT1 and MT2. MT1 is highly expressed in the SCN and the hypophysial pars tuberalis (PT), an important interface for control of seasonal functions. The expression of the MT2 is more widespread. The role of the melatoninergic system in the control of seasonal functions, such as reproduction, has been known for more than 4 decades, but investigations on its impact on the circadian system under normal (entrained) conditions started 2 decades later by comparing mouse strains with a fully functional melatoninergic system with mouse strains which either produce insufficient amounts of melatonin or lack the melatonin receptors MT1 and MT2. These studies revealed that an intact melatoninergic system is not required for the generation or maintenance of rhythmic behavior under physiological entrained conditions. As shown by jet lag experiments, the melatoninergic system facilitated faster re-entrainment of locomotor activity accompanied by a more rapid adaptation of the molecular clock work in the SCN. This action depended on MT2. Further studies indicated that the endogenous melatoninergic system stabilizes the locomotor activity under entrained conditions. Notably, these effects of the endogenous melatoninergic system are subtle, suggesting that other signals such as corticosterone or temperature contribute to the synchronization of locomotor activity. Outdoor experiments lasting for a whole year indicate a seasonal plasticity of the chronotype which depends on the melatoninergic system. The comparison between mice with an intact or a compromised melatoninergic system also points toward an impact of this system on sleep, memory and metabolism.

Body procurement in the Dr. Senckenbergische Anatomie in Frankfurt/Main after the Second World War - From unclaimed corpses to body bequests.

The present paper provides a detailed historical and numerical analysis of the processes regarding body procurement in a particular German anatomical institute, namely, the Dr. Senckenbergische Anatomie (DSA) in Frankfurt am Main. It covers the period from 1946 to 1980; i.e. the transitional phase during which unclaimed corpses were replaced by corpses stemming from body donors. The DSA is fortunate to possess the complete set of records spanning that period. Thus, we cannot only document the (failed) organizational and political efforts of the local anatomists and governmental agencies to uphold the unclaimed body system of old, but we can also present rather detailed data regarding the genesis of the system of body donations. In particular, we will provide evidence that this system was more or less self-generating, and that its emergence was not actively propagated by the local anatomists. Instead, it was triggered by both the media and by the donors themselves, with the latter acting as multipliers. In addition we provide, for the first time, data on the efficacy (in terms of "file corpses" vs. real corpses in anatomy) of a body donation system in Germany.

Seasonal Variations of Locomotor Activity Rhythms in Melatonin-Proficient and -Deficient Mice under Seminatural Outdoor Conditions.

Locomotor activity patterns of laboratory mice are widely used to analyze circadian mechanisms, but most investigations have been performed under standardized laboratory conditions. Outdoors, animals are exposed to daily changes in photoperiod and other abiotic cues that might influence their circadian system. To investigate how the locomotor activity patterns under outdoor conditions compare to controlled laboratory conditions, we placed 2 laboratory mouse strains (melatonin-deficient C57Bl and melatonin-proficient C3H) in the garden of the Dr. Senckenbergische Anatomie in Frankfurt am Main. The mice were kept singly in cages equipped with an infrared locomotion detector, a hiding box, nesting material, and with food and water ad libitum. The locomotor activity of each mouse was recorded for 1 year, together with data on ambient temperature, light, and humidity. Chronotype, chronotype stability, total daily activity, duration of the activity period, and daily diurnality indices were determined from the actograms. C3H mice showed clear seasonal differences in the chronotype, its stability, the total daily activity, and the duration of the activity period. These pronounced seasonal differences were not observed in the C57Bl. In both strains, the onset of the main activity period was mainly determined by the evening dusk, whereas the offset was influenced by the ambient temperature. The actograms did not reveal infra-, ultradian, or lunar rhythms or a weekday/weekend pattern. Under outdoor conditions, the 2 strains retained their nocturnal locomotor identity as observed in the laboratory. Our results indicate that the chronotype displays a seasonal plasticity that may depend on the melatoninergic system. Photoperiod and ambient temperature are the most potent abiotic entraining cues. The timing of the evening dusk mainly affects the onset of the activity period; the ambient temperature during this period influences the latter's duration. Humidity, overall light intensities, and human activities do not affect the locomotor behavior.

Synchronizing effects of melatonin on diurnal and circadian rhythms.

In mammals, the rhythmic secretion of melatonin from the pineal gland is driven by the circadian clock in the suprachiasmatic nucleus (SCN) of the hypothalamus. The robust nightly peak of melatonin secretion is an output signal of the circadian clock and is supposed to deliver the circadian message to the whole of the organism. Since the circadian system regulates many behavioral and physiological processes, its disruption by external (shift-work, jet-lag) or internal desynchronization (blindness, aging) causes many different health problems. Externally applied melatonin is used in humans as a chronobiotic drug to treat desynchronization and circadian disorders, and the success of these treatments does, at first glance, underline the supposed pivotal role of melatonin in the synchronization of the circadian system. On the other hand, pinealectomy in experimental animals and humans does not abolish their rhythms of rest and activity. Furthermore, mice with deficient melatoninergic systems neither display overt defects in their rhythmic behavior nor do they show obvious signs of disease susceptibility, let alone premature mortality. During the last years, our laboratory has investigated several mouse stains with intact or compromised internal melatonin signaling systems in order to better understand the physiological role of the melatoninergic system. These and other investigations which will be reviewed in the present contribution confirm the synchronizing effect of endogenous melatonin and the melatoninergic system. However, these effects are subtle. Thus melatonin does not appear as the master of internal synchronization, but as one component in a cocktail of synchronizing agents.

The Role of the Melatoninergic System in Light-Entrained Behavior of Mice.

The role of endogenous melatonin for the control of the circadian system under entrained conditions and for the determination of the chronotype is still poorly understood. Mice with deletions in the melatoninergic system (melatonin deficiency or the lack of melatonin receptors, respectively) do not display any obvious defects in either their spontaneous (circadian) or entrained (diurnal) rhythmic behavior. However, there are effects that can be detected by analyzing the periodicity of the locomotor behaviors in some detail. We found that melatonin-deficient mice (C57Bl), as well as melatonin-proficient C3H mice that lack the melatonin receptors (MT) 1 and 2 (C3H MT1,2 KO), reproduce their diurnal locomotor rhythms with significantly less accuracy than mice with an intact melatoninergic system. However, their respective chronotypes remained unaltered. These results show that one function of the endogenous melatoninergic system might be to stabilize internal rhythms under conditions of a steady entrainment, while it has no effects on the chronotype.

Melatonin Receptor 1 Deficiency Affects Feeding Dynamics and Pro-Opiomelanocortin Expression in the Arcuate Nucleus and Pituitary of Mice.

BACKGROUND/METHODS: Melatonin, the neurohormone for darkness, mediates photoperiod-dependent changes in physiology and behavior by targeting specific membrane-bound receptors (MT1 and MT2). In the present study, we investigated the impact of MT1 receptor deficiency on feeding behavior, locomotor activity and mRNA expression levels encoding for the polypeptide pro-opiomelanocortin (Pomc) and neuropeptide Y (Npy) in the hypothalamic arcuate nucleus (ARC) and the adenohypophysis [pars distalis (PD) and pars intermedia (PI)] in a comparison between wild-type (WT) and MT1-deficient (MT1-/-) mice. RESULTS: The MT1-/- mice spent significantly more time feeding than the WT mice, while the general locomotor behavior, body weight and the total amount of food consumed did not differ between both genotypes. The nocturnal expression levels of Pomc in the ARC and PD were significantly higher in WT as compared to MT1-/- mice and exogenous melatonin administered during the light phase stimulated Pomc expression in WT mice only. No differences were found between WT and MT1-/- mice with regard to Pomc expression levels in the PI. CONCLUSION: Thus, the MT1-mediated signaling stimulates Pomc expression in a region-specific pattern. Since the MT1-mediated changes in Pomc expression do not elicit direct orexigenic or anorexigenic effects, such effects are obviously mediated by regulatory systems downstream of the Pomc mRNA (e.g. cleavage and release of POMC derivatives), which are independent of MT1 signaling.

Impact of Ataxin-2 knock out on circadian locomotor behavior and PER immunoreaction in the SCN of mice.

In Drosophila melanogaster, Ataxin-2 is a crucial activator of Period and is involved in the control of circadian rhythms. However, in mammals the function of Ataxin-2 is unknown despite its involvement in the inherited neurogenerative disease Spinocerebellar Ataxia type 2 in humans. Therefore, we analyzed locomotor behavior of Atxn2-deficient mice and their WT littermates under entrained- and free-running conditions as well as after experimental jet lag. Furthermore, we compared the PER1 and PER2 immunoreaction (IR) in the SCN. Atxn2-/- mice showed an unstable rhythmicity of locomotor activity, but the level of PER1 and PER2 IR in the SCN did not differ between genotypes.

Notes on the history of the Dr. Senckenbergische Anatomie in Frankfurt/Main. Part I. Development of student numbers, body procurement, and gross anatomy courses from 1914 to 2013.

Until recently, it was believed that all internal documentation regarding student affairs and body procurement of the Dr. Senckenbergische Anatomie concerning the time before March 1944 - when the building was destroyed during an Allied air raid - was lost. A few years ago, however, we discovered stacks of old documents in the current anatomy building. These documents permitted a reconstruction (1) of the history of body procurement, student numbers and course management from 1914 to 1944, as well as (2) some aspects of the building's history in the time immediately after its destruction that have hitherto not been documented. In this paper (Part I), we will deal with the organizational history of the Dr. Senckenbergische Anatomie from 1914 to 2013, placing special emphasis on the development of the student population and body procurement, as well as on the major changes that occurred in the gross anatomy labs of the last century. More than 30,000 students were trained in the Dr. Senckenbergische Anatomie over the last 100 years, and more than 3000 bodies have been received. The number of incoming bodies has remained quite stable in all these years and is, on average, approximately 32 per year. The number of students entering the gross anatomy lab during that period, however, rose from less than 100 to more than 600. A companion paper (Part II) deals with the years of the Third Reich (1933-1945) in more detail.

Notes on the history of the Dr. Senckenbergische Anatomie in Frankfurt/Main. Part II. The Dr. Senckenbergische Anatomie during the Third Reich and its body supply.

In order to be able to understand how body supply was maintained at the Dr. Senckenbergische Anatomie from 1933 to 1945 - with special emphasis on victims of the National Socialist regime - we have collected information from various and often fragmentary sources. The documents reveal that during this period at least 474 bodies were brought to the anatomical institute. Among them were the bodies of at least 71 prisoners, 51 of whom had been executed, and the bodies of 8 inmates of (labor-) camps. 356 unclaimed bodies were received, some of them may stem from victims of "euthanasia" programs. The sources of 39, as of yet, unnamed bodies could not be verified. The current collections and the catalogs were screened for remains of victims of the National Socialist regime, but none were found. The vast majority of the bodies were used for teaching purposes. Hans Schreiber, one of the directors of the institute, whose biography is provided here, used at least 9 additional executed individuals for his research. Wherever possible, we have identified the victims of the National Socialist regime, executed persons and the inmates of (labor-) camps, whose bodies were used by the anatomists in Frankfurt, by name. Among the victims was Georg Fröba, a communist philanthropist, whose biography is provided.

Owls and larks in mice.

Humans come in different chronotypes and, particularly, the late chronotype (the so-called owl) has been shown to be associated with several health risks. A number of studies show that laboratory mice also display various chronotypes. In mice as well as in humans, the chronotype shows correlations with the period length and rhythm stability. In addition, some mouse models for human diseases show alterations in their chronotypic behavior, which are comparable to those humans. Thus, analysis of the behavior of mice is a powerful tool to unravel the molecular and genetic background of the chronotype and the prevalence of risks and diseases that are associated with it. In this review, we summarize the correlation of chronotype with free-running period length and rhythm stability in inbred mouse strains, in mice with a compromised molecular clockwork, and in a mouse model for neurodegeneration.

The brainstem pathologies of Parkinson's disease and dementia with Lewy bodies.

Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are among the human synucleinopathies, which show alpha-synuclein immunoreactive neuronal and/or glial aggregations and progressive neuronal loss in selected brain regions (eg, substantia nigra, ventral tegmental area, pedunculopontine nucleus). Despite several studies about brainstem pathologies in PD and DLB, there is currently no detailed information available regarding the presence of alpha-synuclein immunoreactive inclusions (i) in the cranial nerve, precerebellar, vestibular and oculomotor brainstem nuclei and (ii) in brainstem fiber tracts and oligodendroctyes. Therefore, we analyzed the inclusion pathologies in the brainstem nuclei (Lewy bodies, LB; Lewy neurites, LN; coiled bodies, CB) and fiber tracts (LN, CB) of PD and DLB patients. As reported in previous studies, LB and LN were most prevalent in the substantia nigra, ventral tegmental area, pedunculopontine and raphe nuclei, periaqueductal gray, locus coeruleus, parabrachial nuclei, reticular formation, prepositus hypoglossal, dorsal motor vagal and solitary nuclei. Additionally we were able to demonstrate LB and LN in all cranial nerve nuclei, premotor oculomotor, precerebellar and vestibular brainstem nuclei, as well as LN in all brainstem fiber tracts. CB were present in nearly all brainstem nuclei and brainstem fiber tracts containing LB and/or LN. These findings can contribute to a large variety of less well-explained PD and DLB symptoms (eg, gait and postural instability, impaired balance and postural reflexes, falls, ingestive and oculomotor dysfunctions) and point to the occurrence of disturbances of intra-axonal transport processes and transneuronal spread of the underlying pathological processes of PD and DLB along anatomical pathways.

Chronotypes and rhythm stability in mice.

Humans come in different chronotypes: The phase of their sleep-wake cycle with respect to the phase of the external, sidereal cycle of night and day differs. Colloquially, the early chronotypes are addressed as "larks," the late ones as "owls." The human chronotype can be quantified in hours and minutes of local time by determining the median of the sleep phase. Demographically, early and late human chronotypes differ with respect to the stability of their rhythms and the prevalence of several widespread diseases and risk factors, such as depression, nicotine abuse, and others. Inbred mice are widely used in chronobiological research as model organisms, but up to now there was no way to chronotype them. We have developed a method to chronotype mice in hours and fractions of hours by measuring the median of activity (MoA) and have shown that different mouse strains have significantly different MoAs and, thus, chronotypes. We have further developed methods to estimate the stability of the behavioral rhythms and found that "late" mice have relatively instable rhythms. Our methods permit the use of inbred mice for investigations into the molecular and genetic background of the chronotype and the prevalence of risks and diseases that are associated with it.

Spatial and temporal expression patterns of Bmal delineate a circadian clock in the nervous system of Branchiostoma lanceolatum.

We cloned the homologue of the clock gene Bmal from a cephalochordate, Branchiostoma lanceolatum (syn. amphioxus). Amphioxus possesses a single copy of this gene (amphiBmal) that encodes for a protein of 649 amino acids, which is quite similar to BMALs of other chordates. The gene is expressed by a restricted cell group in the anterior vesicle of the neural tube, and its expression site coincides with that of another clock gene, namely, amphiPer. The expression of amphiBmal shows a rhythmic fluctuation that persists under constant darkness and is, thus, circadian. Similar to the situation in craniates, the peak phases of the amphiBmal and amphiPer expression are offset by 12 hours. Based on these observations and the putative homology between the diencephalon of vertebrates and the anterior vesicle of lancelets, we suggest a homology between the suprachiasmatic nucleus of craniates and the amphiBmal/amphiPer-expressing cell group of amphioxus.

Nocturnal behavior and rhythmic period gene expression in a lancelet, Branchiostoma lanceolatum.

The authors here present the first anatomical, molecular biological, and ethological data on the organization of the circadian system of a lancelet, Branchiostoma lanceolatum, a close invertebrate relative of vertebrates. B. lanceolatum was found to be a nocturnal animal and, since its rhythmic activity persisted under constant darkness, it also appears to possess an endogenous, circadian oscillator. The authors cloned a homolog of the clock gene Period (Per), which plays a central (inhibitory) role in the biochemical machinery of the circadian oscillators of both vertebrates and protostomians. This gene from B. lanceolatum was designated as amphiPer. Both the sequence of its cDNA and that of the predicted protein are more similar to those of the Per paralogs of vertebrates than to those of the single protostomian Per gene. A strong expression of amphiPer was found in a small cell group in the anterior neural tube. The amphiPer mRNA levels fluctuated in a rhythmic manner, being high early in the day and low late at night. The authors' data suggest a homology of the amphiPer expessing cells to the suprachiasmatic nucleus of vertebrates.

The dissection course - necessary and indispensable for teaching anatomy to medical students.

Anatomy is a major basic subject in medicine and related biomedical sciences. A central tool most universities use for teaching anatomy is the "dissection course", in which medical students learn the basic constructional principles of the human body by dissecting a cadaver. In recent years, the relevance and value of the dissection laboratory have been under discussion at different universities due to high costs and problems of shortness in time in some medical curricula. Indeed, during the last 10 years, several universities in the US and the UK have abandoned dissection and have moved from a cadaver-oriented to a cadaverless anatomy. This development results in a fundamental discussion on the role of the "dissection course" in the medical curriculum, ultimately raising the question as to whether we should continue teaching anatomy by dissection. This article presents nine arguments for the dissection course as a central tool for teaching macroscopic anatomy and is an attestment to the continuation of the use of cadaver material in anatomical laboratories within the auspices of scholastic and university order for the benefit of future physicians with due respect and honour guaranteed for every donor.

Distribution of transcription factor inducible cyclicAMP early repressor (ICER) in rodent brain and pituitary.

In morphogenetic dynamics of neurons, and in adaptive physiology of brain function, transcription factors of the cyclicAMP signaling pathway, such as activator cyclicAMP responsive element binding protein (CREB) and inhibitor inducible cyclicAMP early repressor (ICER), play an important role. In particular, the presence of the transcription factor ICER in neurons or neuroendocrine cells suggests the need for the gating of an up-regulated gene expression. Little is known, however, about the natural distribution of the inhibitory transcription factor ICER. We, therefore, mapped the rodent brain and pituitary for an ICER immunoreaction and found a nuclear staining for this transcription factor. ICER-positive glial cells were found throughout the brain. ICER-positive neurons were found in sensory input centers, like the olfactory bulb, or sensory brain stem nuclei, and in hypothalamic nuclei involved in central neuroendocrine control. In addition, neuroendocrine/endocrine transducers, like the pituitary and the pineal gland showed a high basal presence of ICER. Our data show that a basic ICER level is required by many cell systems and can be seen as an anticipatory and/or a protective measure in systems with superior reactive dynamics.

Bone-implant interface around titanium implants under different loading conditions: a histomorphometrical analysis in the Macaca fascicularis monkey.

BACKGROUND: Bone healing around endosseous dental implants is associated with peri-implant loading conditions. Therefore, the aim of this study was to evaluate histomorphometrically the bone response around unloaded, delayed, and immediately loaded implants with a progressive thread design that were placed in the posterior regions of the lower jaw in monkeys. METHODS: Nine adult monkeys (Macaca fascicularis) were used in this study. After extraction of the second premolars and first and second molars in the mandible, the bone was allowed to heal for a period of 3 months. Forty-eight 8 mm long implants with a diameter of 3.5 mm were placed according to the following protocol. In two of the monkeys, six implants were placed and left to heal submerged for 3 months (group A). In seven monkeys, 21 implants were placed in one side of the mandible and loaded after 3 months of submerged healing (group B). The group B implants were loaded with temporary resin bridges at the same time as another 21 implants that were loaded immediately (group C) after placement in the contralateral side of the mandibles of the same monkeys. The occlusion of group B and C implants was checked for optimal relationship of the resin bridges that were replaced 1 month later with metal bridges and loaded for an additional 2 months. The group A animals were sacrificed after 3 months of submerged healing without loading; group B and C animals were sacrificed after 3 months of implant loading. Specimens were examined histologically and histomorphometrically. RESULTS: All implants osseointegrated without presenting any gap in the metal-bone interface. Compact cortical bone was found in contact with the implant surfaces. Group A implants demonstrated in the interface cancellous bone with loose connective tissue. Group B and C implants showed a thick cortical plate with extensive bone trabeculae formation. There was a significant difference in bone-to-implant contact (BIC) between the various loading conditions. No significant difference (P < 0.05) was found between groups B and C. There was an increased area of bone (BA) within the threads as well as around the apices of group B and C implants. CONCLUSIONS: Implant loading might have stimulated increased bone formation and thus may be a key factor in influencing positive osseointegration. In addition, immediately loaded implants may osseointegrate in a similar manner as delayed loaded implants.

Cytoarchitecture, topography, and descending supraspinal projections in the anterior central nervous system of Branchiostoma lanceolatum.

The central nervous system (CNS) of the chordate amphioxus (Branchiostoma lanceolatum) is divisible into a spinal cord and an anterior portion in some ways equivalent to the brain of craniates. The present study reports on this anterior portion, with respect to general topography, cytoarchitecture, and cells that give rise to descending supraspinal projections. The anterior portion of the CNS is located adjacent to the first four myomeres and rostral to the first giant cell of Rohde-it can be divided into several regions that differ with respect to their cytoarchitecture. The tip of the neural tube is formed by a small anterior vesicle; caudally, there is a much larger region that is intercalated between the anterior vesicle and the first cell of Rohde. This intercalated region, in turn, consists of three subdivisions: an anterior subdivision adjacent to myomere 1, an intermediate subdivision adjacent to myomere 2, and a posterior one adjacent to myomeres 3 and 4. After injections of tracers into the spinal cord a large number of cells were labeled in the intercalated region. The spinally projecting cells were not evenly distributed: their number was decreased in the center of the intermediate subdivision. These subdivisions, which have previously not been noted, may be aligned with the expression domains of regulatory genes (e.g., AmphiOtx, AmphiHox) in larval lancelets. In particular, the center of the intermediate subdivision may correspond to a "nonHox/nonOtx" domain in the CNS of the larva. A similar embryonic domain occurs in the brain of craniates in which it develops into the isthmus cerebri that separates mid- and hindbrain. A close structural and topographical inspection of the corresponding region of adult lancelets reveals, however, that this region is not the homolog of an isthmus, but a uniquely derived, autapomorphic feature of lancelets.