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d ‐Aspartate Oxidase Localisation in Pituitary and Pineal Glands of the Female Pig
Author(s) -
Yamamoto A.,
Tanaka H.,
Ishida T.,
Horiike K.
Publication year - 2010
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1111/j.1365-2826.2010.02066.x
Subject(s) - pinealocyte , medicine , endocrinology , immunocytochemistry , pituitary gland , biology , proopiomelanocortin , polyclonal antibodies , cytoplasm , hypothalamus , pineal gland , hormone , chemistry , biochemistry , antibody , melatonin , immunology
Recent evidence has shown that d ‐aspartate modulates hormone secretion in the vertebral neuroendocrine system. Because only d ‐aspartate oxidase (DDO) can degrade d ‐aspartate, we determined DDO localisation in the pituitary and pineal glands to elucidate the control mechanisms of local d ‐aspartate concentration. Brain tissues and pituitary and pineal glands of the female pigs contained a similar DDO activity of 0.38–0.66 U/g protein. However, approximately ten‐fold higher concentrations of d ‐aspartate (0.27–0.35 μmol/g protein) were found in both glands. To determine the distribution of immunoreactive DDO, we made a rabbit polyclonal antibody specific to porcine DDO using a recombinant porcine enzyme. DDO immunoreactivity was found in the cytoplasm of a subgroup of cells in the anterior and intermediate lobes, in a part of nerve processes and terminals in the posterior lobe, and in the cytoplasm of a small group of pinealocytes. We used dual‐label immunocytochemistry to determine which pituitary hormones colocalise with DDO, and whether DDO and d ‐aspartate immunoreactivity is reciprocal. In the pituitary gland, almost all proopiomelanocortin‐positive cells colocalised DDO, whereas only growth hormone‐positive cells colocalised d ‐aspartate. d ‐Aspartate immunoreactivity was not detected where DDO immunoreactivity was found. The present study suggests that DDO plays important roles to prevent undesirable off‐target action of d ‐aspartate by strictly controlling local d ‐aspartate concentration in the pituitary and pineal glands.