Tyrosine hydroxylase- and neuropeptide Y-immunoreactive nerve fibers in the pineal complex of untreated rats and rats following removal of the superior cervical ganglia

Abstract

The distribution of tyrosine hydroxylase (TH)- and neuropeptide Y (NPY)-immunoreactive(IR) nerve fibers in the pineal complex was investigated in untreated rats and rats following bilateral removal of the superior cervical ganglia. In normal animals, a large number of TH- and NPY-IR nerve fibers were present in the pineal capsule, the perivascular spaces, and intraparenchymally between the pinealocytes throughout the superficial pineal and deep pineal gland. A small number of TH-IR and NPY-IR nerve fibers were found in the posterior and habenular commissures, a few fibers penetrating from the commissures into the deep pineal gland. To elucidate the origin of these fibers, the superior cervical ganglion was removed bilaterally in 10 animals, and the pineal complex was examined immunohistochemically. Two weeks after the ganglionectomy, the TH-IR and NPY-IR nerve fibers in the superficial pineal gland had almost completely disappeared. On the other hand, in the deep pineal and the pineal stalk, the TH-IR and NPY-IR fibers were still present after ganglionectomy. These data show that the deep pineal gland and the pineal stalk possess an extrasympathetic innervation by TH-IR and NPY-IR fibers. It is suggested that the extrasympathetic TH-IR and NPY-IR nerve fibers innervating the deep pineal and the pineal stalk originate from the brain.

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

“…NPY is partly of sympathetic origin, colocalized with NE, since a large portion of the NPY fibers disappears after SCGx. This has been reported in the rat (Zhang et al, 1991), sheep (Cozzi et al, 1992), cat , and European hamster . In the mink, the majority of NPY fibers are of extra-sympathetic origin (Møller et al, 1990b).…”

“…The first demonstration of the presence of neurotransmitters in the rat pineal gland was made using the technique of Falck et al (1962), which showed the presence of NE in the sympathetic fibers of the pineal gland. In the rat (Zhang et al, 1991) and sheep (Cozzi et al, 1992) pineal gland most of the tyrosine hydroxylase (TH; the rate-limiting enzyme for NE synthesis) immunoreactive fibers disappear after the SCG removal (SCGx). The remaining fibers could originate from central neurons.…”

Tyrosine hydroxylase positive nerves and mast cells in the porcine gallbladder

“…Since it is generally thought that the reaction of tyrosine hydroxylase (TH) is the initial and rate-limiting step of the catecholamine biosynthetic pathway, the enzyme would appear to play a central role in the regulation of catecholamine production (Levitt et al, 1965;Gordon et al, 2008). TH activity has been observed in many organs such as the adrenal glands, pancreas, liver, intestines, stomach, heart, brain, autonomic ganglia and pineal gland (Teitelman et al 1981;Sternini & Brecha, 1985;Goehler & Sternini, 1991;Zhang et al 1991;Oomori et al, 1994;Persson-Sjogren et al, 1998;Milner, 2004), and it is considered to regulate the blood flow and secretory activities in these tissues. Distribution of the nerve cells and fibres positive for tyrosine hydroxylase is investigated in detail in the different layers of the gallbladder's wall in humans (Mann et al, 1991;Uemura et al, 1997) and dogs (Mann et al, 1991).…”

Neuropeptide Y as a presynaptic modulator of norepinephrine release from the sympathetic nerve fibers in the pig pineal gland

“…Among neurotransmitters occurring in the pineal nerve endings, norepinephrine (NE) and neuropeptide Y (NPY) are present in the highest amounts (Williams et al 1989, Møller 1990, Møller et al 1990, 1996, Zhang et al 1991, Cozzi et al 1992, Olcese 1994, Reuss and Olcese 1995, Drijfhout et al 1996a, Mikkelsen and Møller 1999, Simonneaux and Ribelayga 2003. Both substances co-exist in the sympathetic nerve fibers, but NPY also occurs in a small population of non-sympathetic fibers, probably of the central origin , Zhang et al 1991, Møller et al, 1996, Møller 1999.…”

“…Both substances co-exist in the sympathetic nerve fibers, but NPY also occurs in a small population of non-sympathetic fibers, probably of the central origin , Zhang et al 1991, Møller et al, 1996, Møller 1999. Unquestionably, NE is the essential factor stimulating the secretory activity of pinealocytes in all mammals, however, the mechanisms of adrenergic regulation of melatonin synthesis exhibit strong species heterogeneity (Coon et al 1995, Schomerus 2000, Stehle et al 2001, Simonneaux and Ribelayga 2003, Lewczuk et al 2005, Chattoraj et al 2009).…”