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D-aspartate modulates melatonin synthesis in rat pinealocytes
1Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Japan.
Neuroscience Letters
|July 31, 1998
Summary
D-aspartate, found in high levels in rat pinealocytes, inhibits norepinephrine-driven melatonin synthesis. This suggests D-aspartate acts as a negative regulator of melatonin production in the pineal gland.
Area of Science:
- Neuroendocrinology
- Biochemistry
Background:
- Pinealocytes, the primary cells of the pineal gland, exhibit the highest intracellular concentrations of D-aspartate among rat neuroendocrine cells.
- Melatonin synthesis is a critical function of the pineal gland, regulated by norepinephrine signaling.
Purpose of the Study:
- To investigate the role of D-aspartate in regulating melatonin synthesis in the rat pineal gland.
- To determine the effect of exogenous D-aspartate on norepinephrine-dependent melatonin production.
Main Methods:
- Incubation of rat pineal glands with varying concentrations of D-aspartate.
- Measurement of melatonin synthesis and serotonin N-acetyltransferase (SNAT) activity.
- Quantification of D-aspartate release using high-performance liquid chromatography (HPLC) with a chiral column.
Main Results:
- Exogenous D-aspartate significantly inhibited norepinephrine-stimulated melatonin synthesis, with an IC50 of 75 microM.
- The inhibitory effect was partly attributed to reduced norepinephrine-dependent SNAT activity.
- D-aspartate was observed to be released from pinealocytes into the incubation medium over time.
Conclusions:
- D-aspartate functions as a negative regulator of melatonin synthesis in the rat pineal gland.
- The findings elucidate a novel regulatory mechanism involving D-aspartate in pineal gland function.