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2015 Ocular melatonin rhythms in the goldfish
$221 20"i 4
SOMATOSTATIN DEPLETION INDUCES CIRCADIAN RHYTHM OF VIP LEVEL IN THE RAT SUPRACHIASMATIC NUCLEUS CHIAKI FUKUHARA !,2 AND SH1N-ICHI T. INOUYE 1 1 Mitsubishi Kasei Institute of Life Sciences, 11, MinamiOoya, Machida, Tokyo 194, Japan and 2 Life Science Institute, Sophia University, Tokyo 102, Japan The suprachiasmatic nucleus (SCN) contains a circadian pacemaker responsible for the generation and regulation of circadian rhythms in mammals. Neurons which synthesize vasoactive intestinal polypeptide (VIP) are found in the ventrolateral (VL) portion of the SCN. Cellular level of VIP has been shown to be dependent on photic stimuli, but remains constant under continuous dark (DD) conditions. On the other hand, neurons in the dorsomedial (DM) aspect of the SCN contain somatostatin (SS) whose content shows a circadian rhythm that has a peak during the subjective day and a trough during the subjective night, irrespective of environmental lighting conditions. Existence of synaptic contacts between SS terminals and VIP perikarya in the rat SCN indicates a possible interaction between these neurons. To assess this possibility, VIP content in the SCN was determined in the present study in rats administered with a SS depletor and kept under DD conditions. Cellular level of peptides in the SCN was determined by enzyme immunoassay. A circadian rhythm in SS and a stable level of VIP were observed in the SCN of saline administered rats under DD conditions. Administration of a SS depictor, cysteamine, significantly reduced SS level in the SCN within 5 min after i.p. injection, and this low level was maintained for longer than one day. Effect of cysteamine was also shown to be independent of circadian time. This reduction of SS level gave rise to circadian rhythmic changes of VIP level in the SCN, with a peak during the subjective day and a trough during the subjective night. The present results suggest a role of interaction between the two subdivisions in proper operation of the circadian pacemaker in the SCN.
201 5
O C U L A R M E L A T O N I N R H Y T H M S IN T H E GOLDFISH. M A S A Y U K I IIGO, RITSUKO O H T A N I - K A N E K O AND'TAKURO
Department o f Anatomy r St. Kawasaki 216 r Japan.
Marianna
University
School
SUZUKIf of M e d i c i n e r Miyamae-ku,
It is well known that m e l a t o n i n is synthesized in the retina as well as in the pineal gland in avian and a m p h i b i a n species and that the retina and pineal are important components of the c i r c a d i a n system. In fishes, on the other hand, the retina is also considered to be a component of the t e l e o s t e a n circadian system. However, little is known on ocular m e l a t o n i n rhythms. Therefore, the present study is conducted in order to investigate effects of various photoperiods and pinealectomy on ocular m e l a t o n i n rhythms in the goldfish, Carassius auratus as our experimental model. We first identified melatonin using a r e v e r s e - p h a s e HPLC system. Then, we d e t e r m i n e d ocular m e l a t o n i n contents by specific RIA. M e l a t o n i n contents in the g o l d f i s h eye e x h i b i t e d marked daily rhythms under LD 12:12 w i t h higher levels o b s e r v e d during the dark-phase. Ocular melatonin contents s i g n i f i c a n t l y increased both at m i d - l i g h t and m i d - d a r k after p i n e a l e c t o m y as compared w i t h s h a m - o p e r a t e d control. Melatonin rhythms under DD or LL are now under investigation.
20"1 (3
CIRCADIAN RHYTHMS OF MELATONIN RELEASE FROM THE PINEAL ORGAN OF LAMPREY IN VITRO. MICHIKAZU SAMEJIMA, KATSUHISA UCHIDA, SATOSHI TAMOTSU AND YUKITOMO MORITA, l~Deoartment of Phvsiolo~v, Hamamatsu University School of Medicine, 3600 Handa-cho, Hamamatsu 431-31, Japan. The pineal organ of river lampreys (Lampetrajaponica) is essential Io maintain the circadian locomotor activity rhythm. Pinealectomy eliminates the rhythmicity and it is re.stored when pineal organ was transplanted. Melatonin is a pineal hormone which closely related to circadian rhythm. Melatonin content in the pineal organ and serum is usually low in photophase and high in scotophase. However, in the pineal organ and serum of the lamprey, melatonin content hz vivo did not change significantly at the temperature of 10*C where the circadian locomotor activity rhylhm was observed. We incubated the pineal organs in culture plates with M199 medium at 20°C and measured the melatonin in the superfusate by radioimmunoassay. Melatonin excretion rhythms were observed undcr both light-dark and continuous dark (DD) conditions. The circadian excretion of melatonin-from the cultured pineal organs continued for at least five cycles under DD condition. This indicates that the pineal organ of lampreys has circadian oscillator, while ir is to be clarified if the oscillator in the pineal organ is functioning as the oscillator for the locomotor activity rhythm.
SOMATOSTATIN DEPLETION INDUCES CIRCADIAN RHYTHM OF VIP LEVEL IN THE RAT SUPRACHIASMATIC NUCLEUS CHIAKI FUKUHARA !,2 AND SH1N-ICHI T. INOUYE 1 1 Mitsubishi Kasei Institute of Life Sciences, 11, MinamiOoya, Machida, Tokyo 194, Japan and 2 Life Science Institute, Sophia University, Tokyo 102, Japan The suprachiasmatic nucleus (SCN) contains a circadian pacemaker responsible for the generation and regulation of circadian rhythms in mammals. Neurons which synthesize vasoactive intestinal polypeptide (VIP) are found in the ventrolateral (VL) portion of the SCN. Cellular level of VIP has been shown to be dependent on photic stimuli, but remains constant under continuous dark (DD) conditions. On the other hand, neurons in the dorsomedial (DM) aspect of the SCN contain somatostatin (SS) whose content shows a circadian rhythm that has a peak during the subjective day and a trough during the subjective night, irrespective of environmental lighting conditions. Existence of synaptic contacts between SS terminals and VIP perikarya in the rat SCN indicates a possible interaction between these neurons. To assess this possibility, VIP content in the SCN was determined in the present study in rats administered with a SS depletor and kept under DD conditions. Cellular level of peptides in the SCN was determined by enzyme immunoassay. A circadian rhythm in SS and a stable level of VIP were observed in the SCN of saline administered rats under DD conditions. Administration of a SS depictor, cysteamine, significantly reduced SS level in the SCN within 5 min after i.p. injection, and this low level was maintained for longer than one day. Effect of cysteamine was also shown to be independent of circadian time. This reduction of SS level gave rise to circadian rhythmic changes of VIP level in the SCN, with a peak during the subjective day and a trough during the subjective night. The present results suggest a role of interaction between the two subdivisions in proper operation of the circadian pacemaker in the SCN.
201 5
O C U L A R M E L A T O N I N R H Y T H M S IN T H E GOLDFISH. M A S A Y U K I IIGO, RITSUKO O H T A N I - K A N E K O AND'TAKURO
Department o f Anatomy r St. Kawasaki 216 r Japan.
Marianna
University
School
SUZUKIf of M e d i c i n e r Miyamae-ku,
It is well known that m e l a t o n i n is synthesized in the retina as well as in the pineal gland in avian and a m p h i b i a n species and that the retina and pineal are important components of the c i r c a d i a n system. In fishes, on the other hand, the retina is also considered to be a component of the t e l e o s t e a n circadian system. However, little is known on ocular m e l a t o n i n rhythms. Therefore, the present study is conducted in order to investigate effects of various photoperiods and pinealectomy on ocular m e l a t o n i n rhythms in the goldfish, Carassius auratus as our experimental model. We first identified melatonin using a r e v e r s e - p h a s e HPLC system. Then, we d e t e r m i n e d ocular m e l a t o n i n contents by specific RIA. M e l a t o n i n contents in the g o l d f i s h eye e x h i b i t e d marked daily rhythms under LD 12:12 w i t h higher levels o b s e r v e d during the dark-phase. Ocular melatonin contents s i g n i f i c a n t l y increased both at m i d - l i g h t and m i d - d a r k after p i n e a l e c t o m y as compared w i t h s h a m - o p e r a t e d control. Melatonin rhythms under DD or LL are now under investigation.
20"1 (3
CIRCADIAN RHYTHMS OF MELATONIN RELEASE FROM THE PINEAL ORGAN OF LAMPREY IN VITRO. MICHIKAZU SAMEJIMA, KATSUHISA UCHIDA, SATOSHI TAMOTSU AND YUKITOMO MORITA, l~Deoartment of Phvsiolo~v, Hamamatsu University School of Medicine, 3600 Handa-cho, Hamamatsu 431-31, Japan. The pineal organ of river lampreys (Lampetrajaponica) is essential Io maintain the circadian locomotor activity rhythm. Pinealectomy eliminates the rhythmicity and it is re.stored when pineal organ was transplanted. Melatonin is a pineal hormone which closely related to circadian rhythm. Melatonin content in the pineal organ and serum is usually low in photophase and high in scotophase. However, in the pineal organ and serum of the lamprey, melatonin content hz vivo did not change significantly at the temperature of 10*C where the circadian locomotor activity rhylhm was observed. We incubated the pineal organs in culture plates with M199 medium at 20°C and measured the melatonin in the superfusate by radioimmunoassay. Melatonin excretion rhythms were observed undcr both light-dark and continuous dark (DD) conditions. The circadian excretion of melatonin-from the cultured pineal organs continued for at least five cycles under DD condition. This indicates that the pineal organ of lampreys has circadian oscillator, while ir is to be clarified if the oscillator in the pineal organ is functioning as the oscillator for the locomotor activity rhythm.