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Clinical Aspects on the Role of Prolactin in Human Breast Cancer
Published in Nagasawa Hiroshi, Prolactin and Lesions in Breast, Uterus, and Prostate, 2020
The first two criteria of the paraneoplastic syndrome are fulfilled by hyperprolactinemia in breast cancer. We have investigated whether the latter two criteria (namely autonomy and lack of rhythmicity) apply to the hyperprolactinemia associated with breast cancer. The objective of the investigation was, therefore, to clarify whether the hyperprolactinemia in breast cancer might be a paraneoplastic syndrome. In order to answer this question, stimulation and suppression tests were performed and 24 hr hormone profiles were plotted in breast cancer patients with raised PRL levels. Included in the study were 34 patients with metastasized breast cancer. First of all, a PRL stimulation test with 200 μg TRH (thyrotropin-releasing hormone) i.v. was carried out on the patients and the rise of PRL measured after 30 min. Afterwards, the patients received either 12 mg metergoline or 10 mg bromocriptine p.o. over a period of 30 days for PRL suppression. Metergoline is a serotonin antagonist which blocks the hyperthalamic 5-HT receptors and thus indirectly leads to PRL suppression via a hypothalamic point of action. Bromocriptine is a pure dopamine agonist which occupies the dopamine receptors of the adenohypophysis and thus brings about a suppression of PRL secretion and synthesis at the hypophyseal level.
Neurobiological Substrates Mediating the Reinforcing Effects of Psychomotor Stimulant and Opiate Drugs
Published in Edythe D. London, Imaging Drug Action in the Brain, 2017
Carol B. Hubner, George F. Koob
Other experiments have utilized antagonists to investigate the role of serotonin in the reinforcing effects of psychomotor stimulants. Systemic injections of metergoline, a long-acting serotonin receptor antagonist, produced significant increases in responding for d-amphetamine only 4 to 5 h into the experimental session (Lyness and Moore, 1983). These results suggest that the reinforcing effects of amphetamine were attenuated by serotonin antagonist pretreatment. However, previous studies have demonstrated that the serotonergic antagonist activity of metergoline occurs within 1 h following its administration (Clineschmidt and Lotti, 1974), a time at which changes in amphetamine self-administration were not observed. In addition, metergoline has effects on dopaminergic systems, but only at later times after injection (Spano et al., 1978; Hofmann et al., 1979; Lyness and Moore, 1983). Thus, the change in rates of amphetamine self-administration may be due to the dopaminergic rather than the serotonergic actions of metergoline.
Pharmacotherapy and nutritional supplements for seasonal affective disorders: a systematic review
Published in Expert Opinion on Pharmacotherapy, 2018
Olivia Cools, Kaat Hebbrecht, Violette Coppens, Laurence Roosens, Andy De Witte, Manuel Morrens, Hugo Neels, Bernard Sabbe
Metergoline is a serotonin antagonist. Turner et al. tested its hypothetical tryptophan depletion effect on three patients with SAD, but the results of their pilot study suggested otherwise [72]. The same research group subsequently set up a DB-RCT on metergoline vs. placebo and found a significant difference in effect with an overall SIGH-SAD score decrease of −26% for metergoline and −5% for placebo [72].