, to restore gonadal function, to reduce tumor size, and to preserve or improve residual pituitary function. Prolactin secretion in the normal pituitary is tonically inhibited by hypothalamic dopamine through dopamine D2 receptors (Drd2) expressed on
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M Victoria Recouvreux, M Andrea Camilletti, Daniel B Rifkin, and Graciela Díaz-Torga
Hiroharu Mifune, Yuji Tajiri, Yusuke Sakai, Yukie Kawahara, Kento Hara, Takahiro Sato, Yoshihiro Nishi, Akinori Nishi, Ryouichi Mitsuzono, Tatsuyuki Kakuma, and Masayasu Kojima
cerebral cortex and nucleus accumbens (NAc) ( Phillips et al. 2007 ). Recent studies have shown that mesolimbic dopamine neurons in the ventral tegmental area (VTA) that project to the NAc represent a critical site for ghrelin to trigger food consumption
Ebony T Gilbreath, Lakshmikripa Jaganathan, Madhan Subramanian, Priya Balasubramanian, Katrina D Linning, Sheba M J MohanKumar, and Puliyur S MohanKumar
reach middle age. During this time, serum estradiol levels are moderately elevated for a period of 6 months. This results in a gradual decline in hypothalamic dopamine levels with a concurrent increase in serum prolactin levels. This chronic
Helen L Henderson, Julie Townsend, and Domingo J Tortonese
, our laboratory demonstrated a seasonal modulation of the combined suppressive effects of PRL and dopamine on the gonadotrophin response to GnRH ( Gregory et al . 2004 ). An immortalised gonadotroph cell line, αT 3 -1, has been shown to express D 2
Daniel J Tobiansky, George V Kachkovski, Reilly T Enos, Kim L Schmidt, E Angela Murphy, and Kiran K Soma
system, a circuit comprised of dopamine (DA) synthesizing neurons in the ventral tegmental area (VTA) and DA-sensitive neurons in the nucleus accumbens (NAc), medial prefrontal cortex (mPFC), hippocampus (HPC), and other areas ( Ikemoto 2007 ). This
R. P. DEIS and NIA ALONSO
An action of dopamine on kidney function has been reported by McDonald, Goldberg, McNay & Tuttle (1964) in man and by McNay, McDonald & Goldberg (1963) in dogs. We have studied the effect of dopamine (D) (3,4 dihydroxyphenylethylamine HCl; Nutritional Biochemical Co.) on diuresis in rats.
Male rats (200–300 g.) of the Instituto strain were used. They were trained for 3 days to minimize the effect of stress and observations made both during water diuresis and at normal rates of urine flow. Water diuresis was induced by giving tap water by stomach tube (4 ml./100 g. body wt). After placing the rats in a special container, urine was collected every 30 min. for 2 hr. and the bladder was gently pressed before and after each 30-min. period to ensure complete evacuation. Dopamine (2 mg./100 g. body wt) was administered i.p. in 0·2 ml. saline. In five rats with normal rates
M Arvigo, F Gatto, M Ruscica, P Ameri, E Dozio, M Albertelli, M D Culler, M Motta, F Minuto, P Magni, and D Ferone
heterodimerize with other G-protein-coupled receptors, such as the μ-opioid receptor ( Pfeiffer et al . 2002 ) and dopamine (DA) type 2 receptor (D 2 R; Rocheville et al . 2000 b , Baragli et al . 2007 ). The heterodimerization of these G
M. G. P. Gallardo, M. Bilinski, S. R. Chiocchio, and J. H. Tramezzani
ABSTRACT
The presence of dopamine in the lactotroph cell, as well as in isolated prolactin secretory granules, was demonstrated by means of an histochemical reaction for electron microscopy. Biochemical assays further confirmed the presence of dopamine in the secretory granules.
Autoradiographic preparations examined by light microscopy showed dopamine internalization in dispersed anterior pituitary cells.
Isolated anterior pituitary lactotroph cells incorporated more [3H]dopamine than a fraction containing other anterior pituitary cells.
J. Endocr. (1985) 104, 23–28
R. Fraser
Dopamine is capable of modulating zona glomerulosa function. Of this there now seems little doubt. However, whether varying dopamine levels in vivo forms the basis of a realistic normal physiological control mechanism for aldosterone secretion is far from clear. Reviewers have been cautious (Ganguly, 1984) or enthusiastic (Sowers, 1984) depending on the choice of evidence and the weight given to individual studies, but some resolution of the uncertainty is pressing since aberrations in this as yet unproven relationship have been suggested as basic abnormalities in a number of forms of hypertensive disease.
Evidence for and against the dopamine–aldosterone relationship has been obtained using dopamine itself and antagonists or agonists of its action in whole animals and in tissue preparations. Initial impetus for the dopamine hypothesis came from the observation that the dopamine agonist, bromocriptine, inhibited the response of aldosterone to frusemide-induced sodium loss (Edwards, Thorner, Miall et al. 1975) although
M. C. Macnamee and P. J. Sharp
ABSTRACT
An assessment was made of the possible role of hypothalamic dopamine in the regulation of changes in plasma prolactin and LH in laying and broody bantam hens. Specific dopamine-binding sites were identified, using [3H]domperidone, in the anterior pituitary gland and in the anterior and posterior hypothalamus. The mean concentrations of dopamine-binding sites in both parts of the hypothalamus were 59–66 fmol/mg protein and did not differ between laying and incubating hens. The concentration of dopamine binding sites in the anterior pituitary gland was significantly (P<0·001) greater in laying than in incubating hens (278 ± 46 compared with 420 ± 32 fmol/mg protein, n = 5).
The turnover rates of dopamine were compared in the anterior and posterior hypothalami of laying, incubating and nest-deprived hens. The turnover rates were estimated from the rate of accumulation of dopamine after inhibiting its catabolism using the monoamine oxidase inhibitor, pargyline, or by measuring the ratio of the concentrations of dopamine and its major metabolite, homovanillic acid. Both methods gave the same results. The turnover of dopamine was increased in the anterior but not posterior hypothalamus of incubating hens when compared with laying or nest-deprived hens.
These results show, for the first time in birds, that the anterior pituitary gland contains specific binding sites for dopamine and that the concentration of these binding sites is inversely related to the concentration of plasma prolactin. The marked increase in dopaminergic activity in the anterior hypothalamus of incubating hens may stimulate the release of unidentified prolactin-releasing factors and/or inhibit the release of LH by exerting an inhibitory influence in the area of the hypothalamus containing LHRH cell bodies.
Journal of Endocrinology (1989) 121, 67–74
