rsc mu 2013
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The Insight of Chronobiology with
an Emphasis on the Nightly Surge
of Serotonin Output in the RatPineal Gland and the Role of TPH1
Asamanja Chattoraj, PhD
Scient is t -D; Anim al Bioresources ProgrammeINSTITUTE OF BIORESOURCES & SUSTAINABLE DEVELOPMENT (IBSD)
DEPARTMENT OF BIOTECHNOLOGY, GOVERNMENT OF INDIA
Takyelpat, Imphal795001, Manipur (India)
Email: [email protected]@gmail.com
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What is chronobiology?
Biological rhythm persisting as a fundamental property of biologic entities under various
conditions of presumed constancy in environmental factors.
The formal study of biological temporal rhythms such as daily, tidal, weekly, seasonal,
and annual rhythms is called chronobiology.
A circadian rhythm is an endogenously driven roughly 24-hour cycle in biochemical,
physiological, or behavioural processes.
Circadian rhythms have been widely observed, in plants, animals, fungi and
cyanobacteria.
The term "circadian" comes from the Latin
circa, meaning "around", and
diem or
dies,
meaning "day".
Although circadian rhythms are endogenous ("built-in", self-sustained), they are adjusted
(entrained) to the environment by external cues called zeitgebers, the primary one of
which is daylight.
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Travelling of Light into the Mammalian Pineal Gland
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Importance of Melatonin and Serotonin
Serotonin:
Neurotransmitter
Control of appetite Sleep Memory and learning Temperature regulation Mood Behavior (including sexual and hallucinogenic behavior) Cardiovascular function Muscle contraction Endocrine regulation Depression
Melatonin:
Sleep-Wakefulness Cycle Reproduction
Hibernation Hypertension Cell Proliferation Seasonal Affective Disorders Immune-Response Jet-lag Scavenger of Free Radicals
Aging 6
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The pineal gland of all vertebrates produces 5-HT.
The synthesis of 5-HT from tryptophan requires two enzymes:
a) Tryptophan Hydroxylase 1(TPH1) which limits the rate of 5-HT production and
b) Aromatic Amino Acid Decarboxylase,constitutively expressed at high levels.
TPH1 enzyme activity displays a two fold increase in the night pineal gland of rats.
A number of studies points to an essential role of -adrenargic signallingin the
regulation of TPH1 activity.
In vitro studies also pointed out the role of cAMP and PKAin the activity of TPH1.
PKA phosphorylates TPH1 in vitro at serine 58 residue.
It remains unknown , whether PKA elevates TPH1 activity by increasing its protein
stability and whether TPH1 is phosphorylated in v ivo at the S58 site.
Existing Information
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Aims of the Present Study
The regulation of nocturnal increase of 5-HT total
output in the night pineal gland.
The role of cAMP signaling in 5-HT synthesis in vivo.
The role of TPH1 phosphorylationin the regulation of
TPH1 protein content.
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DARKLIGHT
TPH1 mRNA Expression is NOT Under Circadian Control In Rat Pineal
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Night-time TPH1 mRNA Expression is INSENSIBLE to Light Exposure
1010
1: No Light
2: 10 mints Light
3: 24 hr Light
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Measurement of Pineal Indoleamines by Microdialysis
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5-HT Total Output and TPH1 Protein Levels Display
Dramatic Circadian Rhythms
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Cyclic AMP Signaling in the Pineal Gland Stimulates
the Total Output of 5-HT in v ivo
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TPH1 is Phosphorylated at the S58 in the Night Pineal Gland
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Light Pulses at Night Suppress the Nocturnal Increase of both 5-
HT Total Output and TPH1 Protein Levels in the Living Pineal Gland
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Conclusion and Summary
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Melatonin as Bioindicator for Oocyte
maturation in carp.
Fish Gut Microflora and Melatonin: A
Chronobiological Study on Indian Major
Carp
Current Research
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The Group
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Acknowledgement
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I am grateful to my mentor Prof. S.K. Maitra,
Department of Zoology, Visva-Bharati, West-Bengal,INDIA, for everything I have learned and still learningfrom him.
I am thankful to Dr Jimo Borjigin,MIP, Universityof Michigan, USA For helping me in my post-doctoralstudies.
Financial Support from United States Air force and
NIH, USA, are thankfully acknowledged.
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