epidermal-growth-factor and quinagolide

Somatostatin analogues such as octreotide have been shown in experimental systems to exhibit antineoplastic activity. Further laboratory and clinical research is needed to clarify the mechanism of action of somatostatin analogues as antineoplastics, and to determine if the encouraging preclinical results will lead to novel endocrine approaches to the treatment of breast cancer.

Topics: Aminoquinolines; Breast Neoplasms; Epidermal Growth Factor; Estradiol; Female; Humans; Insulin-Like Growth Factor I; Octreotide; Prolactin; Somatostatin

In order to assess whether a chronic treatment with a dopamine agonist, CV205-502, could modulate anterior pituitary epidermal growth factor (EGF) binding sites, female Wistar rats were treated or not (controls) with CV205-502 0.25 mg/kg/day sc for 8 days. This treatment significantly reduced rats' pituitary weight and plasma prolactin levels when compared to controls (weight: 10.4 +/- 0.1 vs 11.1 +/- 0.1 mg, p less than 0.01; prolactin: 1.2 +/- 0.2 vs 4.9 +/- 0.5 ng/ml, p less than 0.01). These decreases were associated with a significant stimulation of the number of pituitary EGF binding sites Bmax: 16.7 +/- 2.3 vs 11.3 +/- 1.9 fmoles/mg proteins, p less than 0.01) with no significant effect on their affinity (Kd: 0.94 +/- 0.17 vs 0.95 +/- 0.14 nM). Therefore, the modulation of pituitary EGF binding sites might be one of the mechanisms by which the dopamine agonist, CV205-502, exerts its pharmacological effects on hormonal secretions and/or cell multiplication in the pituitary.

Topics: Aminoquinolines; Animals; Binding Sites; Dopamine Agents; Epidermal Growth Factor; Female; Injections, Subcutaneous; Pituitary Gland, Anterior; Prolactin; Rats; Rats, Inbred Strains; Stimulation, Chemical