[Show abstract][Hide abstract] ABSTRACT: Somatostatin receptors are an important target for medical treatment of pituitary and neuroendocrine tumors. To date, five somatostatin receptor (sst) subtypes have been identified. The currently available somatostatin analogues octreotide and lanreotide have predominantly affinity for sst. Pasireotide is a sst multireceptor ligand with affinity for sst, sst, sst and sst and this broader binding profile may translate into a higher efficacy with respect to suppression of hormone production and cell growth in certain tumors. Experimental animal studies and in vitro studies with cultured tumor cells have shown that pasireotide strongly suppresses growth hormone and adrenocorticotropin production. In addition, pasireotide can influence tumor cell growth via effects on apoptosis and angiogenesis. In this review, the role of somatostatin receptors in pituitary and neuroendocrine tumors is briefly discussed followed by an overview of possible applications of pasireotide based on recent trials in patients with acromegaly, Cushing's disease and neuroendocrine tumors.
[Show abstract][Hide abstract] ABSTRACT: RATIONALE: Extrapyramidal motor signs are the major features of Parkinson's disease (PD). It is unclear whether there is a link between these signs and such PD-associated factors as brain somatostatin deficiency and aging. OBJECTIVES: This study aimed to examine whether an inhibition of the brain somatostatin system can initiate catalepsy, a model of extrapyramidal disorders, in young and aged rats. METHODS: The animals of 100-110 and 540-560 days of age were used. Catalepsy was measured using the bar test. The inhibition of the brain somatostatin activity was simulated by intracerebroventricular administration of a somatostatin antagonist, cyclosomatostatin. RESULTS: Cyclosomatostatin dose-dependently induced catalepsy in aged, but not in young rats. The cataleptic response was reversed by a somatostatin analog, octreotide. CONCLUSIONS: The combination of aging and brain somatostatin deficiency can lead to catalepsy in rats. Since both factors are frequently observed in PD patients, the present results might be of relevance for pathogenesis of extrapyramidal signs in this disease.
[Show abstract][Hide abstract] ABSTRACT: Regulation of cellular responses to external stimuli such as hormones, neurotransmitters, or cytokines is achieved through the control of all steps of the complex cascade starting with synthesis, going through maturation steps, release, distribution, degradation and/or uptake of the signalling molecule interacting with the target protein. One possible way of regulation, referred to as scavenging or neutralization of the ligand, has been increasingly studied, especially for small protein ligands. It shows innovative potential in chemical biology approaches as well as in disease treatment. Neutralization of protein ligands, as for example cytokines or chemokines can lead to the validation of signalling pathways under physiological or pathophysiological conditions, and in certain cases, to the development of therapeutic molecules now used in autoimmune diseases, chronic inflammation and cancer treatment. This review explores the field of ligand neutralization and tries to determine to what extent small chemical molecules could substitute for neutralizing antibodies in therapeutic approaches.
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