Tachykinins and tachykinin‐receptors in the rat pineal gland

Abstract

High-pressure liquid chromatography of extracts of rat pineal glands, followed by radio immunological analysis with antibodies against tachykinins, demonstrated the presence of substance P, neurokinin A and neurokinin B in the superficial rat pineal gland. Immunohistochemistry on perfusion-fixed rat brain sections showed substance P and neurokinin A to be present in nerve fibers located both in the perivascular spaces as well as intraparenchymally between the pinealocytes. After extracting total RNA, followed by reverse transcription and polymerase chain reaction amplification with primers specific for NK1-, NK2- and NK3-receptors, agarose gel analysis of the reaction products showed the presence of mRNA encoding all three neurokinin receptors. Immunohistochemical analysis showed NK1 receptor to be located in the interstitial cells of the gland. This location was confirmed by use of in situ hybridization using radioactively labeled antisense oligonucleotide probes. Double immunohistochemical stainings showed that the NK1-immunoreactive cells were not a part of the macrophages or antigen-presenting cells of the gland. Our study suggests that tachykinins, after release from intrapineal nerve fibers, are involved in an up to now unknown function, different from that of melatonin synthesis.

Expression of the Otx2 homeobox gene in the developing mammalian brain: embryonic and adult expression in the pineal gland

“…Cryostat sections 14 µm thick were cut from three animals and mounted on Superfrost Plus ® slides. Immunohistochemistry was performed as described previously (Mukda et al . 2005).…”

“…Primary antibody, polyclonal goat anti‐human Otx2 IgG (R & D Systems, Abingdon, UK), was diluted to 10 µg/mL; secondary antibody, biotinylated donkey anti‐goat IgG (Jackson, Soham, UK), was diluted 1 : 500. Chromogenic development was done by incubation in Avidin‐Biotin‐peroxidase complex followed by diaminobenzidine (Mukda et al . 2005).…”

The Melatonergic System in Mood and Anxiety Disorders and the Role of Agomelatine: Implications for Clinical Practice

“…Indeed, early studies demonstrated that, besides SCN innervation, the pineal gland receives projections from sphenopalatine, otic and trigeminal ganglia [60], which have been reported to secrete substance P [61]. Recent works demonstrated that pinealocytes are enriched with substance P receptors [62] and that substance P may inhibit norepinephrine-induced AANAT activation and melatonin secretion, though it does not impair basal levels of AANAT functioning [63]. …”

Tachykinins and the hypothalamo–pituitary–gonadal axis: An update

“…It was previously shown that SP is present in the pineal gland, which in turn can modulate pituitary secretion of different hormones [15,56,72], such as the gonadotropins. It was recently demonstrated that SP can modulate melatonin secretion by the pineal gland, therefore potentially being able to influence gonadotropin secretion [57].…”