Expression of brain nitric oxide synthase in the developing rat pineal gland coincides with the appearance of the adrenergic cyclic guanosine 3',5'-monophosphate response.

In the developing rat pineal gland, norepinephrine (NE)-stimulated cyclic guanosine 3',5'-monophosphate (cGMP) formation appears 2 weeks later than that of cyclic adenosine 3',5'-monophosphate (cAMP) formation. Since NE-stimulated cGMP formation requires formation of nitric oxide (NO) in the adult rat pineal, we investigated the developmental appearance of the NO-forming enzyme brain NO-synthase (NOS) to find out whether the delayed cGMP response results from the late appearance of NOS. In this study, we investigated pineal glands of rats aged 8-21 days and 8 weeks. Western blot analysis revealed that NOS-immunoreactivity (NOS-IR) was barely detectable until day 12. On day 15 NOS-IR exhibited the same intensity as in adult rats. Expression of NOS at this postnatal stage appears to be responsible for the developmental appearance of the adrenergic cGMP response.