Anterior pituitary dopamine receptor

Modulation of the anterior pituitary dopamine receptor by gonadal steroids... 

It has in fact been convincingly demonstrated that the anterior pituitary dopamine receptor is negatively coupled to adenylate cyclase in both tumoral (26), and normal (54) adenohypophysial tissue. Thus, the adenohypophysis cannot be taken, as originally proposed (36), as example of a receptor not coupled to adenylate cyclase. Moreover, it is well known that some dopaminergic responses appear independent of cyclic AMP (74, 75, 76). In order to take into account all the available data, it appears preferable to use the terminology DA+, DA and DA. (54, Fig. 4). Other advantages of this terminology are its clear separation from the nomen-... 

The classification of dopamine receptors. Although Kebabian and Caine Q) performed an excellent service to the scientific community in proposing the D-l and D-2 receptor hypothesis, this remains to be proven by isolating and characterizing these receptors. These have been excellently reviewed by Cronin (2). Indeed the statement that the "D" receptors of the anterior pituitary are independent of adenylate cyclase is incorrect. We (3) and others (4, ) have shown a consistant and specific inhibitory relationship of the anterior pituitary dopamine receptor and adenylate cyclase. 

Prolactin is an essential hormone for normal production of breast milk following childbirth. It also plays a pivotal role in a variety of reproductive functions. Prolactin is regulated primarily by the hypothalamus-pituitary axis and secreted solely by the lactotroph cells of the anterior pituitary gland. Under normal conditions, secretion of prolactin is predominantly under inhibitory control by dopamine and acts on the D2 receptors located on the lactotroph cells. Increase of hypothalamic thyrotropin-releasing hormone (TRH) in primary hypothyroidism can stimulate the release of prolactin. 

Radiolabelled cis-flupenthixol can be used as a ligand specific for the dopamine receptor linked to adenylyl cyclase in the rat striatum (64). Its affinity for the dopamine receptor in the anterior pituitary has not been measured. (Previously (65) the two categories of dopamine receptors were designated as a-dopaminergic" and P-dopaminergic. This has led to confusion with the a and p adrenoreceptors. The new designations should prevent further confusion.)... 

Commentary The DA Dopamine Receptor in the Anterior and Intermediate Lobes of the Pituitary Gland... 

The dopamine receptor in the anterior pituitary gland is negatively coupled to adenylate cyclase... 

As much as higher concentrations of dopamine are required to stimulate striatal adenylate cyclase activity as compared to the affinity of the drug for the agonistic sites of the receptor, the sensitivity of the anterior pituitary adenylate cyclase to dopamine agonists in both human prolactinoma (26) and rat adenohypophysial homogenate (31) is lower than the potency of the compounds to inhibit prolactin secretion in intact cells (2). This variable loss of sensitivity upon cell homogeneization is a phenomenon frequently observed in other systems (32). 

All the data presented above point to the involvement of a putative guanine nucleotide binding protein in the interaction of agonists with the dopamine receptor in the porcine anterior pituitary gland. We, therefore, wanted to obtain more compelling evidence for the interaction of a nucleotide binding... 

Solubilization by Digitonin of Agonist and Antagonist Prelabelled Dopamine Receptor from Anterior Pituitary Gland Membranes... 

CARON et al. Anterior Pituitary Gland s Dopamine Receptor... 

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