Modulation of Pineal Melatonin Synthesis by Glutamate Involves Paracrine Interactions between Pinealocytes and Astrocytes through NF-𝜿B Activation

Figure 2

Glutamate effects on melatonin synthesis. (a) Pineal gland culture stimulated with norepinephrine (NE 1 μM) in the absence or presence of glutamate (Glu 100 and Glu 600 μM). Melatonin content is expressed in ng/gland as the mean ± SEM of 3 experiments. One-way ANOVA, Bonferroni multiple comparison test, ^∗𝑃<0.05 versus NE 1 μM, 𝑛=12 for each group. (b) Isolated rat pinealocyte culture under NE 1 μM stimulation in the absence or presence of Glu 100 or Glu 600 μM. 𝑛=6 for each group. (c) Pinealocyte and astrocyte co-culture stimulated with NE 1 μM in the absence or presence of Glu 100 or Glu 600 μM. One-way ANOVA, Bonferroni multiple comparison test, ^∗∗𝑃<0.01 versus NE 1 μM, 𝑛=8 for each group. (d) Astrocytes and pinealocytes were cultured together but with physical separation by inserts. Astrocytes were cultivated in the bottom of the plate, and pinealocytes were cultivated within the inserts and stimulated with NE 1 μM, associated or not associated with Glu 600 μM. 𝑇 test, ^∗∗𝑃<0.01, 𝑛=4 for each group. For the cell cultures, melatonin was evaluated in the culture medium and expressed in ng/mL as the mean ± SEM of 3 experiments.

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