M. Eriksson et al., DISTRIBUTION AND ORIGIN OF PEPTIDE-CONTAINING NERVE-FIBERS IN THE RATAND HUMAN MAMMARY-GLAND, Neuroscience, 70(1), 1996, pp. 227-245
The structures in the mammary gland involved in milk ejection have bee
n investigated with regard to their relation to different types of pep
tidergic nerve fibres and their origin. Lactating rats were studied wi
th immunohistochemistry focusing on the nipple, the parenchyma, the ma
mmary blood vessels and the mammary nerve. The human mammary gland was
also analysed. In the mammary gland from rat and human, nerve endings
in the subepidermis, around smooth muscle cells in the nipple, in the
connective tissue surrounding lactiferous ducts and alveoli in the ni
pple and in the parenchyma of the mammary gland showed immunoreactivit
y for calcitonin gene-related peptide, substance P, vasoactive intesti
nal polypeptide, peptide histidine isoleucine, neuropeptide Y, galanin
and tyrosine hydroxylase, whereas dynorphin-positive nerve fibres cou
ld not be detected. The mammary nerve contained calcitonin gene-relate
d peptide, vasoactive intestinal polypeptide, neuropeptide Y and tyros
ine hydroxylase immunoreactivities; the adventitia of the mammary arte
ry contained nerve fibres immunoreactive for neuropeptide Y and tyrosi
ne hydroxylase, while vasoactive intestinal polypeptide-, peptide hist
idine isoleucine-, calcitonin gene-related peptide- and substance P-po
sitive fibres were found in the tissue surrounding the artery. The wal
l of the mammary vein had nerve terminals immunoreactive or neuropepti
de Y, tyrosine hydroxylase, calcitonin gene-related peptide and substa
nce P. With the help of retrograde tracing using wheat germ agglutinin
in combination with immunohistochemistry, projections of calcitonin g
ene-related peptide-immunoreactive cells in the dorsal root ganglia to
the nipple were established. Neurons in the sympathetic stellate gang
lion containing neuropeptide Y and tyrosine hydroxylase also projected
to the mammary gland. Moreover retrogradely-labelled cells were found
in the nodose ganglion, and they were vasoactive intestinal polypepti
de-immunoreactive. These results demonstrate a rich distribution of di
fferent types of nerve fibres in structures of the mammary gland relat
ed to milk ejection. These nerve fibres and. their peptides may be inv
olved in the local control of milk ejection.