Influence on the Endocrine System

Dopaminergic Modulation of the Diethylstilbestrol-Induced Proliferation of the Anterior Pituitary Gland of the Fisher 344 Rat

“…The D-2 dopamine receptor on the surface of the mammotroph is well-established as the site at which dopaminer gic agonists act to inhibit prolactin release [2,6]. The pres ent observations demonstrate that a dopamine receptor (most likely a D-2 receptor) is associated with the prolifer ating mammotrophs of the Fisher 344 rat and that stimula tion of this receptor inhibits the secretion of prolactin from these proliferating cells.…”

“…In many vertebrate species, a D-2 dopamine receptor occur ring on the surface of the mammotroph regulates the re lease and synthesis of prolactin [2,6,12]. Acute stimulation of this receptor inhibits prolactin release [2,6]: more pro longed stimulation diminishes the capacity of the mammo troph to synthesize prolactin [14], In view of our recent de monstration that chronic stimulation of the D-2 receptor in the intermediate lobe causes this structure to atrophy and earlier demonstrations suggesting a dopaminergic attenua tion of estrogen-induced proliferation of the pituitary gland, it seemed worthwhile to investigate the effects of 2-bromo-alpha-ergocryptine (CB 154) upon the DES-in duced proliferation of the mammotrophs of the Fisher 344 rat pituitary gland [1,8,9,13]. In this communication, we report that CB 154, a potent D-2 agonist, markedly attenu ated the DES-induced proliferation of the mammotrophs of the male Fisher 344 rat [6].…”

The lactation–blocking drug bromocriptine and its application to studies of weaning and behavioral development

“…Although bromocriptine is highly specific for prolactin suppression via its dopaminelike properties, it may have other endocrine effects besides this primary action (Fluckiger, 1980;Fluckiger & Del Pozo, 1978). Reducing prolactin levels is likely to have many central and endocrine consequences which could be classed as side effects of bromocriptine.…”

“…mocriptine also acts in the hypothalamus to enhance the inhibition of prolactin secretion (Fluckiger, 1980;Fluckiger & Del Pozo, 1978). Bromocriptine is not found to affect the milkejection reflex .…”

Role of Serotonin in the Regulation of Ovulation

“…For some of these compounds also CNS site of action has been reported, e.g. for methiothepin, which accelerates the turnover of 5-HT in the rat brain [15], Nevertheless, it should be men tioned that the profile of action of these compounds is complex, influencing besides 5-HT also other biogenic amine systems [16], In this context it is interesting to note that the known dopamine agonist 2-Br-\-ergokryptine [6] was found in our tests to be of the weakest 5-HT antag onists and ovulation inhibiting compounds.…”