Innervation of the rat pineal gland by pituitary adenylate cyclase-activating polypeptide (PACAP)-immunoreactive nerve fibres.
Pituitary adenylate cyclase-activating polypeptide (PACAP)-immunoreactive nerve fibres were demonstrated in the rat pineal gland. These fibres entered the pineal gland through the conarian nerve at the distal tip of the gland. A high density of the fibres was observed in the capsule of the gland, from where the immunoreactive elements penetrated into the pineal perivascular spaces and parenchyma. The majority of PACAP-immunoreactive nerve fibres also contained calcitonin gene-related peptide (CGRP). Some PACAP-immunoreactive nerve fibres contained neuropeptide Y (NPY), but only occasionally was PACAP colocalized with vasoactive intestinal peptide (VIP). After removal of both superior cervical ganglia, a high number of PACAP-containing nerve fibres were still present in the gland. In the nervous system PACAP is present in two isoforms, PACAP-38 and PACAP-27. The concentration of PACAP-38 in the superficial pineal gland was determined by radioimmunoassay to be 20.4 pmol/g tissue at midday and 18.9 pmol/g tissue at midnight. The concentration of PACAP-27 was only about 3% of the concentration of PACAP-38. In summary, this study is the first demonstration of a PACAP-containing innervation of the rat pineal gland. The PACAP concentration in the pineal gland does not exhibit a day-night difference. The colocalization of PACAP with calcitonin gene-related peptide in the pincalopetal nerve fibres indicates that the majority of PACAP-immunoreactive nerve fibres might originate from the trigeminal ganglion.
Møller
M
M
Institute of Medical Anatomy, Panum Institute, Copenhagen, Denmark. morten.m@mai.ku.dk
Fahrenkrug
J
J
Hannibal
J
J
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000032:analysis; D015171:Ganglionectomy; D007150:Immunohistochemistry; D008297:Male; D009412:Nerve Fibers / Q000502:physiology* / Q000648:ultrastructure; D009478:Neuropeptide Y; D009479:Neuropeptides / Q000032:analysis / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000032:analysis; D010870:Pineal Gland / Q000166:cytology / Q000294:innervation*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051381:Rats; D017208:Rats, Wistar; D017783:Superior Cervical Ganglion / Q000502:physiology*; D014660:Vasoactive Intestinal Peptide / Q000032:analysis
C495403:Adcyap1 protein, rat; D009478:Neuropeptide Y; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D014660:Vasoactive Intestinal Peptide; D015740:Calcitonin Gene-Related Peptide