Release of alpha-subunit of glycoprotein hormones from the bullfrog pituitary: possible effect of alpha-subunit on prolactin cell function.
On the basis of our previous finding that prolactin (PRL) cells of the bullfrog (Rana catesbeiana) contain immunoreactive alpha-subunit of pituitary glycoprotein hormones, experiments were conducted to see whether the immunoreactive alpha-subunit is released from PRL cells. Cell immunoblot analysis revealed that approximately 10% of cells that released immunoreactive PRL also released immunoreactive alpha-subunit. Western blot analysis of the culture media revealed that a considerable amount of the free form of alpha-subunit was released from the dispersed anterior pituitary cells. Moreover, it was found that addition of alpha-subunit to the culture medium enhanced PRL release. The results raise the possibility that alpha-subunit secreted by PRL cells acts as an autocrine and/or paracrine factor.
Oguchi
A
A
Department of Biology, School of Education, Waseda University, Nishiwaseda, Shinjuku-ku, Tokyo, Japan.
Tanaka
S
S
Yamamoto
K
K
Kikuyama
S
S
D000818:Animals; D015153:Blotting, Western; D005260:Female; D006023:Glycoproteins / Q000737:chemistry*; D007150:Immunohistochemistry; D010446:Peptide Fragments / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D010907:Pituitary Hormones / Q000737:chemistry*; D011892:Rana catesbeiana / Q000502:physiology*
D006023:Glycoproteins; D010446:Peptide Fragments; D010907:Pituitary Hormones