Different mechanisms between copper and iron in catecholamines-mediated oxidative DNA damage and disruption of gene expression in vitro.

Catechols produce reactive oxygen species (ROS) and induce oxidative DNA damage through reduction-oxidation reactions with metals such as copper. Here, we examined oxidative DNA damage by neurotransmitter catecholamines in the presence of copper or iron and evaluated the effects of this damage on gene expression in vitro. Dopamine induced strand breaks and base oxidation in calf thymus DNA in the presence of Cu(II) or Fe(III)-NTA (nitrilotriacetic acid). The extent of this damage was greater for Cu(II) than for Fe(III)-NTA. For the DNA damage induced by dopamine, the responsible reactive species were hydrogen peroxide and Cu(I) for Cu(II) and hydroxyl radicals and Fe(II) for Fe(III)-NTA. Cu(II) induced DNA conformational changes, but Fe(III)-NTA did not in the presence of dopamine. These differences indicate different modes of action between Cu and Fe-NTA with regard to the induction of DNA damage. Expression of the lacZ gene coded on plasmid DNA was inhibited depending on the extent of the oxidative damage and strand breaks. Endogenous catecholamines (dopamine, adrenaline, and noradrenaline) were more potent than catechols (no aminoalkyl side chains) or 3,4-dihydroxybenzylamine (aminomethyl side chain). These results suggest that the metal-mediated DNA damage induced by dopamine disrupts gene expression, and leukoaminochromes (further oxidation products of O-quinones having aminoethyl side chain) are involved in the DNA damage. These findings indicate a possibility that metal (especially iron and copper)-mediated oxidation of catecholamines plays an important role in the pathogenesis of neurodegenerative disorders including Parkinson's disease.

Individualized high-dose cabergoline therapy for hyperprolactinemic infertility in women with micro- and macroprolactinomas.

CONTEXT: Cabergoline is effective for hyperprolactinemic hypogonadism. However, the rate of cabergoline-induced pregnancy in women with prolactinoma remains unknown. Also unknown is whether cabergoline can control tumor growth and thereby achieve successful pregnancy in patients with macroprolactinomas. METHODS: Eighty-five women with macroprolactinomas (n = 29) or microprolactinomas (n = 56) received prospective, high-dose cabergoline therapy for infertility based on individual prolactin suppression and/or tumor shrinkage. The patients included 31 bromocriptine-resistant, 32 bromocriptine-intolerant, and 22 previously untreated women. Conception was withheld until three regular cycles returned in women with microadenoma and until tumors shrank below 1.0 cm in height in women with macroadenoma. Cabergoline was withdrawn at the fourth gestational week. RESULTS: Cabergoline normalized hyperprolactinemia and recovered the ovulatory cycle in all patients. All adenomas contracted, and 11 macroadenomas and 29 microadenomas disappeared. Eighty patients (94%) conceived 95 pregnancies, two of which were cabergoline-free second pregnancies. The dose of cabergoline at the first pregnancy was 0.25-9 mg/wk overall and 2-9 mg/wk in the resistant patients. Of the 93 pregnancies achieved on cabergoline, 86 resulted in 83 single live births, one stillbirth, and two abortions; the remaining seven were ongoing. All babies were born healthy, without any malformations. No mothers experienced impaired vision or headache suggestive of abnormal tumor reexpansion throughout pregnancy. CONCLUSION: Cabergoline achieved a high pregnancy rate with uneventful outcomes in infertile women with prolactinoma, independent of tumor size and bromocriptine resistance or intolerance. Cabergoline monotherapy could substitute for the conventional combination therapy of pregestational surgery or irradiation plus bromocriptine in macroprolactinomas.

Prospective study of high-dose cabergoline treatment of prolactinomas in 150 patients.

CONTEXT: Cabergoline fails to normalize hyperprolactinemia in a considerable proportion of prolactinomas, especially macroadenomas. OBJECTIVE: We examined the effect of individualized high-dose cabergoline treatment on hyperprolactinemia in prolactinomas. PATIENTS: The study included 122 women and 28 men (93 microadenomas and 57 macroadenomas). Forty-seven had undergone transsphenoidal surgery. According to the preceding medical treatment, the participants were separated into untreated (group U; n = 60), intolerant (group I; n = 64), and resistant (group R; n = 26) groups. INTERVENTIONS: We promptly increased cabergoline dose on the basis of individual prolactin levels. Length of treatment was 1 yr. RESULTS: Cabergoline normalized hyperprolactinemia in all patients except one. The proportion of prolactin normalization in both groups U and I was 83% at 3 months and 95% at 6 months. By contrast, that in group R was 35% at 3 months and 58% at 6 months. Mean cabergoline dose in milligrams per week at the time of prolactin normalization was 2.0 +/- 0.3 in group U, 0.9 +/- 0.1 in group I, and 5.2 +/- 0.6 in group R. Prolactin normalization rate at the 3 mg/wk dose was 84% overall but only 35% in group R. Serum progesterone or testosterone levels, diminished in 122 women or 16 men, respectively, were recovered in all except one resistant and four postmenopausal or panhypopituitary patients. CONCLUSION: Individualized high-dose cabergoline treatment can normalize hyperprolactinemia and hypogonadism in nearly all prolactinomas irrespective of tumor size or preceding treatments. Hyperprolactinemia could be controlled in poor responders within 1 yr with doses higher than 3 mg/wk.