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

Table 1

Summary of intracellular [Ca²⁺] changes in astrocytes and pinealocytes after stimulation.

Cell type/agents	Number of cells examined	[Ca^2+]i response %
Isolated astrocytes
Glu 600 μM	68	79
AMPA 50 μM	97	80
NMDA 100 μM	49	90
DHPG 50 μM	80	74
Isolated pinealocytes
Glu 600 μM	66	80
AMPA 50 μM	78	85
NMDA 100 μM	53	90
DHPG 50 μM	60	76

Intracellular [Ca²⁺] in fluo-4-loaded astrocytes and pinealocytes was measured as described in Section 2. The majority of the stimulated cells responded with an increase in intracellular [Ca²⁺] after the addition of either glutamate (600 μM), ionotropic glutamatergic agonists (AMPA 50 μM and NMDA 100 μM), or a class I metabotropic glutamatergic agonist (DHPG 50 μM).