D2 Dopamine receptor subtype mediates the inhibitory effect of dopamine on TRH-induced prolactin release from the bullfrog pituitary

作者：Nakano Masaki; Minagawa Atsuko; Hasunuma Itaru; Okada Reiko; Tonon Marie Christine; Vaudry Hubert; Yamamoto Kazutoshi; Kikuyama Sakae; Machida Takeo; Kobayashi Tetsuya^*

来源：General and Comparative Endocrinology, 2010, 168(2): 287-292.

DOI：10.1016/j.ygcen.2010.05.008

• Dopamine
• D2 receptor
• Prolactin
• Thyrotropin-releasing hormone
• Pituitary
• Bullfrog

Dopamine receptors in mammals are known to consist of two D1-like receptors (D1 and D5) and three D2-like receptors (D2, D3 and D4). The aim of this study was to determine the dopamine receptor subtype that mediates the inhibitory action of dopamine on the release of prolactin (PRL) from the amphibian pituitary. Distal lobes of the bullfrog (Rana catesbeiana) were perifused and the amount of PRL released in the effluent medium was measured by means of a homologous enzyme-immunoassay. TRH stimulated the release of PRL from perifused pituitaries. Dopamine suppressed TRH-induced elevation of PRL release. Quinpirole (a D2 receptor agonist) also suppressed the stimulatory effect of TRH on the release of PRL, whereas SKF-38393 (a D1 receptor agonist) exhibited no such an effect. The inhibitory action of dopamine on TRH-induced PRL release from the pituitary was nullified by the addition of L-741,626 (a selective D2 receptor antagonist) to the medium, but not by the addition of SCH-23390 (a selective D1 receptor antagonist). These data indicate that the inhibitory effect of dopamine on TRH-evoked PRL release from the bullfrog pituitary gland is mediated through D2 dopamine receptors.

• 出版日期2010-9-1