Neuroendocrinology
-
Despite similar histological and morphological aspects, gastro-enteropancreatic (GEP) endocrine tumours represent a heterogeneous group of tumours with varying clinical expression depending on tumour type (functional or not), origin and extension, but also on histological differentiation and proliferative capacity. The natural history of well-differentiated tumours is often favourable without treatment and GEP endocrine tumours may remain indolent for many years. Chemotherapy may however be indicated in the presence of symptomatic non-progressive disease (progression evaluated over 3-6 months). ⋯ Chemotherapy, using cisplatin and etoposide, is the reference treatment and frequently yields OR rates >50%. However, despite being chemosensitive, disease control is limited (8-10 months). Overall, advances in therapeutic chemotherapeutic options are required in the management of all types of advanced GEP endocrine tumours and evaluation of new drugs (e.g. irinotecan) and combination strategies (chemotherapy with local ablative therapies) are required in the future.
-
Multicenter Study Comparative Study Clinical Trial
Rapid and sustained relief from the symptoms of carcinoid syndrome: results from an open 6-month study of the 28-day prolonged-release formulation of lanreotide.
This 6-month, open, non-controlled, multicenter, dose-titration study evaluated the efficacy and safety of 28-day prolonged-release (PR) lanreotide in the treatment of carcinoid syndrome. Eligible patients had a carcinoid tumor with > or =3 stools/day and/or > or =1 moderate/severe flushing episodes/day. Six treatments of 28-day PR lanreotide were administered by deep subcutaneous injection. ⋯ By month 6, flushing and diarrhea had significantly decreased from baseline by a mean of 1.3 and 1.1 episodes/day, respectively (both p < or = 0.001); 65% of patients with flushing as the target symptom and 18% of diarrhea-target patients achieved > or =50% reduction from baseline. Median urinary 5-hydroxyindoleacetic acid and chromogranin A levels decreased by 24 and 38%, respectively. Treatment was well tolerated. 28-day PR lanreotide was effective in reducing the symptoms and biochemical markers associated with carcinoid syndrome.
-
The neurochemical mechanisms underlying hindbrain glucoprivic suppression of the luteinizing hormone (LH) surge are not known. A body of experimental evidence supports the view that gonadal steroid positive-feedback action on the reproductive neuroendocrine axis relieves tonic GABAergic inhibition of gonadotropin-releasing hormone neurons by diminishing preoptic release of this neurotransmitter. The present studies evaluated the hypothesis that hindbrain glucoprivic attenuation of the LH surge may be correlated with site-specific modifications in gonadal steroid suppression of gamma-aminobutyric acid release in this region of the brain. ⋯ The data show that 5- TG administration increased GABA release within the rostral preoptic area (rPO), anteroventral periventricular nucleus (AVPV), and median preoptic nucleus (MEPO), relative to the vehicle-treated controls, but did not alter neurotransmitter release in other structures evaluated. The rate of GABA turnover in each brain site was equivalent between animals injected with the mu opioid receptor antagonist CTOP and 5-TG versus their vehicle-treated controls. These results constitute novel evidence for site-specific modulation of steroid positive-feedback suppression of this inhibitory neurotransmitter by caudal hindbrain signaling of glucose insufficiency, and support the need for neurochemical characterization of glucoprivic-sensitive afferent input to GABAergic neurons terminating within the rPO, AVPV, and MEPO, as well as the relevance of enhanced local GABA release for reproductive neuroendocrine function.