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Start Over Author "Christof Schomerus" Journal neurosignals
5 results on '"Christof Schomerus"'

1. Melatonin Excretion Rhythms in the Cultured Pineal Organ of the Lamprey, Lampetra japonica

Author

T. Kachi, Stuart E. Dryer, Jiri Vanecek, Takashi Yoshimura, Akihito Adachi, Masayuki Hara, Masaomi Iyo, S. Hashimoto, M.F. Xu, D.J. Kennaway, Y. Saito, Sato Honma, Shizufumi Ebihara, Norio Mori, T. Yamauchi, Takuro Endo, P.M. Iuvone, P. Greve, Theresa D'Souza, S. Kajihara, M. Bernard, T. Irie, Katsumi Aida, Yukitomo Morita, Masayuki Iigo, V.M. Cassone, T. Suzuki, Kazuaki Hirata, M. Kurushima, Michikazu Samejima, Ken-ichi Honma, Satoko Hashimoto, Norio Okamoto, Ondrej Slanar, Norio Suzuki, K. Honma, Gregory M. Cahill, Katsuhisa Uchida, P. Pévet, Satoshi Tamotsu, P.L. Tang, Mitsuo Tabata, Horst-W. Korf, Ritsuko Ohtani-Kaneko, H. Kudou, B. Pitrosky, Susanne Kroeber, Takuya Nogi, D.C. Klein, Hana Zemkova, Christof Schomerus, G. Takahashi, N. Kimura, A. Alonso-Gomez, Minoru Hasegawa, Z.M. Qian, Kanjun Hirunagi, and Yutaka Ohashi

Subjects
endocrine system, medicine.medical_specialty, biology, Lamprey, Endogeny, biology.organism_classification, Melatonin, Excretion, Cellular and Molecular Neuroscience, Rhythm, Endocrinology, Developmental Neuroscience, Neurology, Internal medicine, medicine, Lampetra japonica, Secretion, Circadian rhythm, hormones, hormone substitutes, and hormone antagonists, medicine.drug
Abstract

Pineal organ of the lamprey, Lampetra japonica, is essential to keep the circadian locomotor activity rhythm as previously reported. In this paper, we tried to show that an endogenous oscillator is located and is working in the pineal organ. When the pineal organs were excised and cultured in a plastic tube with M199 medium at 20 degrees C, melatonin secretion rhythms were clearly observed under both light-dark and continuous dark conditions. The circadian secretion of melatonin continued for more than five cycles under the continuous dark condition. This indicates that the pineal organ has an endogenous oscillator and that the melatonin secretion rhythm is controlled by this oscillator. These findings suggest the possibility that the locomotor activity rhythm of the lamprey is under the control of the oscillator in the pineal organ.

Published
1997
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2. Regulation of the Intracellular Concentration of Free Calcium Ions in Pinealocytes of the Rainbow Trout and the Rat

Author

Susanne Kroeber, Horst-W. Korf, and Christof Schomerus

Subjects
Intracellular Fluid, medicine.medical_specialty, Patch-Clamp Techniques, Light, chemistry.chemical_element, Calcium, Biology, Pineal Gland, Calcium in biology, Pinealocyte, Norepinephrine, Cellular and Molecular Neuroscience, Pineal gland, Developmental Neuroscience, Internal medicine, Cyclic AMP, medicine, Animals, L-type calcium channel, Patch clamp, Calcium metabolism, Voltage-dependent calcium channel, Rats, medicine.anatomical_structure, Endocrinology, Neurology, chemistry, Oncorhynchus mykiss, Biophysics
Abstract

Together with cAMP, calcium ions play an important role in the regulation of melatonin synthesis in the pineal organ of all vertebrate species, irrespective of the conspicuous phylogenetic transformation of the melatonin-producing cell, the pinealocyte. Here we address the question how the intracellular concentration of free calcium ions [Ca2+]i is regulated in directly light-sensitive trout pinealocytes and in rat pinealocytes which have lost the direct light sensitivity and respond to norepinephrine. Isolated pinealocytes identified by the S-antigen immunoreaction were investigated by means of the fura-2 technique, image analysis and patch clamp recordings. Approximately 30% of the trout pinealocytes exhibited spontaneous [Ca2+]i oscillations that were not affected by light or dark adaptation of the cells. Removal of extracellular Ca2+ or application of 10 microM nifedipine caused a reversible breakdown of the [Ca2+]i oscillations. Treatments with 60 mM KCl and nifedipine suggest that voltage-gated L-type calcium channels play a major role in the regulation of [Ca2+]i in both oscillating and nonoscillating trout pinealocytes. Experiments with thapsigargin (2 microM) revealed the presence of intracellular calcium stores in 80% of the trout pinealocytes, but their role in the regulation of [Ca2+]i remains elusive. Norepinephrine had no apparent effect on [Ca2+]i in any trout pinealocyte. In rat pinealocytes, [Ca2+]i did not show spontaneous oscillations. Norepinephrine evoked a dramatic biphasic rise in [Ca2+]i in more than 95% of the cells via stimulation of alpha1-adrenergic receptors. The response reflects a combination of calcium mobilization from intracellular, thapsigargin-sensitive calcium stores and an increased calcium influx. Voltage-gated calcium channels of the L-type are present in the rat pinealocyte membrane, but they are not involved in the norepinephrine-induced calcium response. These channels, however, mediate the increase in calcium influx which is observed in virtually all rat pinealocytes upon stimulation with acetylcholine or nicotine. The results show that the mechanisms which regulate [Ca2+]i in pinealocytes are complex and differ considerably between poikilothermic and mammalian species.

Published
1997
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3. Contents Vol. 6, 1997

Author

Takuya Nogi, Masaomi Iyo, S. Hashimoto, D.C. Klein, Norio Mori, M. Kurushima, D.J. Kennaway, Yutaka Ohashi, Norio Suzuki, Ondrej Slanar, K. Honma, Hana Zemkova, Christof Schomerus, H. Kudou, B. Pitrosky, T. Kachi, P. Pévet, M. Bernard, T. Irie, Satoshi Tamotsu, P.L. Tang, Katsuhisa Uchida, Masayuki Iigo, Kanjun Hirunagi, T. Yamauchi, Norio Okamoto, Satoko Hashimoto, Shizufumi Ebihara, S. Kajihara, Gregory M. Cahill, Z.M. Qian, Theresa D'Souza, M.F. Xu, Mitsuo Tabata, Horst-W. Korf, G. Takahashi, N. Kimura, Takuro Endo, Minoru Hasegawa, Ritsuko Ohtani-Kaneko, Yukitomo Morita, Y. Saito, Susanne Kroeber, Jiri Vanecek, Takashi Yoshimura, A. Alonso-Gomez, T. Suzuki, Katsumi Aida, V.M. Cassone, Michikazu Samejima, Ken-ichi Honma, Stuart E. Dryer, Akihito Adachi, P. Greve, Kazuaki Hirata, Masayuki Hara, Sato Honma, and P.M. Iuvone

Subjects
Cellular and Molecular Neuroscience, Developmental Neuroscience, Neurology
Published
1997
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4. Melatonin Receptors in the Spinal Cord

Author

Michikazu Samejima, Ken-ichi Honma, T. Kachi, Gregory M. Cahill, P. Pévet, Ritsuko Ohtani-Kaneko, A. Alonso-Gomez, Hana Zemkova, Theresa D'Souza, Satoko Hashimoto, Takuro Endo, M. Bernard, Norio Mori, Susanne Kroeber, T. Suzuki, Christof Schomerus, M.F. Xu, Masayuki Hara, Shizufumi Ebihara, P.L. Tang, Sato Honma, Yukitomo Morita, P.M. Iuvone, Takuya Nogi, D.C. Klein, D.J. Kennaway, P. Greve, Katsuhisa Uchida, Katsumi Aida, V.M. Cassone, T. Irie, M. Kurushima, Kazuaki Hirata, Stuart E. Dryer, Akihito Adachi, Mitsuo Tabata, Horst-W. Korf, Y. Saito, K. Honma, Z.M. Qian, T. Yamauchi, S. Kajihara, Jiri Vanecek, Takashi Yoshimura, Ondrej Slanar, G. Takahashi, N. Kimura, Norio Suzuki, Satoshi Tamotsu, H. Kudou, B. Pitrosky, Yutaka Ohashi, Kanjun Hirunagi, Masaomi Iyo, S. Hashimoto, Masayuki Iigo, Norio Okamoto, and Minoru Hasegawa

Subjects
medicine.medical_specialty, business.industry, Spinal cord, Melatonin, Cellular and Molecular Neuroscience, Endocrinology, medicine.anatomical_structure, Developmental Neuroscience, Neurology, Internal medicine, medicine, Receptor, business, medicine.drug
Published
1997
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5. Subject Index Vol. 6, 1997

Author

Michikazu Samejima, Ken-ichi Honma, Norio Suzuki, Stuart E. Dryer, Akihito Adachi, T. Yamauchi, Ritsuko Ohtani-Kaneko, T. Suzuki, Satoko Hashimoto, Katsumi Aida, Susanne Kroeber, Gregory M. Cahill, H. Kudou, S. Kajihara, V.M. Cassone, Yutaka Ohashi, B. Pitrosky, P. Greve, M. Kurushima, Katsuhisa Uchida, Masayuki Hara, Masaomi Iyo, S. Hashimoto, M.F. Xu, Takuro Endo, Theresa D'Souza, Y. Saito, Jiri Vanecek, Takashi Yoshimura, D.J. Kennaway, P.L. Tang, P. Pévet, Yukitomo Morita, Masayuki Iigo, Norio Okamoto, Sato Honma, Norio Mori, G. Takahashi, N. Kimura, P.M. Iuvone, T. Kachi, A. Alonso-Gomez, Takuya Nogi, Minoru Hasegawa, Z.M. Qian, D.C. Klein, Kazuaki Hirata, Hana Zemkova, M. Bernard, Kanjun Hirunagi, Satoshi Tamotsu, Christof Schomerus, Mitsuo Tabata, Horst-W. Korf, Shizufumi Ebihara, Ondrej Slanar, T. Irie, and K. Honma

Subjects
Cellular and Molecular Neuroscience, Index (economics), Developmental Neuroscience, Neurology, Statistics, Subject (documents), Mathematics
Published
1997
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