Neuropeptide Y (NPY) innervation of the ovine pineal gland.

A dense network of neuropeptide Y (NPY)-like immunoreactive (NPY-LI) fibres was revealed in the ovine pineal gland at the light microscope level. The dorsal and peripheral regions of the gland contained the most dense concentration of NPY-LI fibres with relatively few fibres in the mid-region and almost none in the pineal stalk. The effect of NPY in conjunction with isoproterenol (ISO) on cyclic AMP (cAMP) accumulation and noradrenaline (NA) on melatonin synthesis was investigated using in vitro techniques. NPY had no effect on the stimulation of cAMP or melatonin synthesis by the adrenergic agonists.