Pineal nitric oxide synthase: characteristics, adrenergic regulation and function

Generation of the Melatonin Endocrine Message in Mammals: A Review of the Complex Regulation of Melatonin Synthesis by Norepinephrine, Peptides, and Other Pineal Transmitters

“…It appears that the ␤ 1 -AR-induced increase in cGMP is mediated by a G s -protein-coupled GC, while ␣ 1 -AR potentiation involves activation of nitric oxide (NO) synthetase (NOS) and the production of NO, which stimulates cytosolic GC, and therefore cGMP production Klein, 1993, 1995). This finding is in agreement with the following observations: Na ϩ nitroprusside (NO donor) stimulates cGMP accumulation in rat pinealocytes (White and Klein, 1993); NE-induced cGMP accumulation is inhibited by NOS inhibitors (Lin et al, 1994); and the Ca 2ϩ /CaM sensitive form of NOS is present and stimulated by NE (Lin et al, 1994). Na ϩ nitroprusside alone is able to stimulate cGMP accumulation, indicating that the role of ␤ 1 -AR activation would be to make the NOS responsive to the Ca 2ϩ /CaM complex.…”

“…NO is involved in NE-induced cGMP synthesis (see Section V.A.2. ; Spessert et al, 1993;White and Klein, 1993;Lin et al, 1994). In addition, NO could be involved in the release of neurotransmitters such as VIP and NE, as already shown in some tissues (Lonart et al, 1992).…”

“…Consequently, cGMP has no effect on the synthesis and release of MEL (Spessert et al, 1992;Lin et al, 1994). However, some effects of cGMP on pineal biochemistry have been reported.…”

“…NO is also synthesized in nonsympathetic (VIPergic) fibers of the sheep and rat pineal gland Lopez-Figueroa et al, 1997). In addition, neuronal NOS is present in the rat (Lin et al, 1994;Schaad et al, 1994Schaad et al, , 1995aLopezFigueroa and Møller, 1996) and cow (Maronde et al, 1995) pinealocytes (but not in the sheep: . Although NO appears to be synthesized only in a small subpopulation of pineal cells, it is thought to be an intercellular messenger acting on all pineal cells (Spessert et al, 1998).…”

Innervation of the Sheep Pineal Gland by Nonsympathetic Nerve Fibers Containing NADPH-diaphorase Activity

“…Recently, nitric oxide (NO) was shown to be synthesized in the mammalian pineal gland (Spessert et al 1993;Lin et al 1994;Maronde et al 1995). This la-bile intercellular messenger molecule has been shown to play a role in many cellular physiological processes (Bredt and Snyder 1992).…”