How different nerve signals control melatonin production in cow pineal cells

Norepinephrine increased the intracellular calcium ion concentration in bovine pinealocytes.

• Alpha(1)-adrenergic receptors were involved in the norepinephrine-induced increase in calcium ion concentration.
• Beta-adrenergic receptor activation enhanced cAMP accumulation and increased both AANAT activity and melatonin secretion.
• Potentiation of AANAT activity by alpha(1)-adrenergic stimulation was observed, but this effect did not extend to cAMP or melatonin production.
• PACAP treatment resulted in small increases in cAMP, AANAT activity, and melatonin biosynthesis in a specific cell subpopulation.
• Neither VIP nor glutamate had any effect on calcium levels, cAMP levels, AANAT activity, or melatonin production.
• Differences in pineal signal transduction mechanisms between cows and rodents were noted, suggesting implications for understanding melatonin regulation in primates.

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