Presence of AVT-, ?-MSH-, LHRH- and somatostatin-like compounds in the rat pineal gland and their relationship with the UMO5R pineal fraction

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

“…However, the original data showing this were the subject of discussion because the immunocytochemistry technique used poorly specific antibodies (see Pévet et al, 1980b for discussion). Later on, the techniques of in situ hybridization (ISH) and reverse transcription followed by polymerization chain reaction (RT-PCR) have confirmed peptide synthesis in mammalian pineal cells.…”

“…In the rat, combined studies of ISH for preproEnk and immunocytochemistry for 5-HT have shown that cells expressing the peptide (approximately 7%) are not pinealocytes, but rather glial cells (Wang et al, 1996). Pineal cells also contain LHRH (rat, Pévet et al, 1980b), SOM (rat, Pévet et al, 1980b;Møller et al, 1995), sP (cotton rat, Matsushima et al, 1994), C-type natriuretic peptide (CNP) (cytoplasmic vesicles of bovine pineal cells, Middendorff et al, 1996). The pineal gland of the Syrian hamster, but not the rat, displays a few cells containing secretoneurin (SN) (Simonneaux et al, 1997a).…”

“…In contrast to VP, the presence of a few OT-containing neuron-like cells in the bovine pineal gland has been demonstrated both by ISH and immunocytochemistry (Badiu et al, 2001). Several studies have shown the presence of high concentrations of type ␣ melanin-stimulating hormone (␣MSH) in the pineal 338 gland of several species (Oliver and Porter, 1978;Vaudry et al, 1978;Pévet et al, 1980b;Schröder et al, 1988). The majority of peptide-containing cells are neuron-like or modified pinealocytes displaying synaptic contacts with the true pinealocytes.…”

“…High concentrations of ␣MSH (180 pg/gland in the rat) have been found in the pinealocytes of several species (Oliver and Porter, 1978;Vaudry et al, 1978;Pévet et al, 1980b;Schröder et al, 1988) suggesting an auto/paracrine role of this peptide in the pineal gland (Pévet et al, 1980b). However, its role in the regulation of pineal metabolism has not been clearly established.…”

“…The presence of SOM in the pineal gland was shown for the first time by Pelletier et al (1975) in the rat (and later on by Pévet et al, 1980b;Finley et al, 1981;Webb et al, 1984;Møller et al, 1995) then in the hamster, gerbil, mouse (Webb et al, 1984), sheep, pig (Lew and Lawson-Willey, 1987), cow (Peinado et al, 1989;Møller et al, 1992), and human (Bouras et al, 1987). The rat pineal gland contains approximately 0.3 to 3 ng SOM/mg protein (Webb et al, 1985).…”