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1. Nociceptive thresholds to noxious mechanical (paw pressure) and thermal (tail flick) stimuli were recorded in conscious rats. The effects of three selective kappa-opioid receptor agonists on the responses to these stimuli were determined following intravenous, intracerebroventricular or intrathecal administration. Results were compared with those(More)
Morphine is one of the analgesics used most to treat chronic pain, although its long-term administration produces tolerance and dependence through neuronal plasticity. The ability of morphine to regulate neuron differentiation in vivo has been reported. However, the detailed mechanisms have not yet been elucidated because of the inability to separate(More)
When we talk about drug addiction, we are really dealing with an extremely complex system in which there still remain many unknowns and where many empty spaces or missing links are still present. Recent studies have identified changes in the expression profiles of several specific miRNAs which affect the interactions between these molecules and their(More)
The C-terminal octapeptide of cholecystokinin (CCK 8) was administered intrathecally to rats. Doses in the nanogram range produced weak but significant antinociception in the paw pressure test five minutes after injection whereas microgram doses of CCK 8 produced hyperalgesia. The CCK 8-induced analgesia or hyperalgesia was not seen in the tail flick test(More)
The difficulty of designing new analgesic drugs is evident in the biochemical maze that results when an opioid agonist binds to opioid receptors, triggering a complex cascade of intracellular mechanisms. In an effort to enhance understanding of the biochemical and pharmacological mechanisms that are responsible for the action of opioid drugs, we describe(More)
Characterization of a newly cloned proopiomelanocortin (POMC) gene in the teleost zebrafish, Danio rerio, is reported. This gene is formed by three exons and two introns, and its complete cDNA codes for a polypeptide of 222 amino acids. Zebrafish proopiomelanocortin (zfPOMC) contains the consensus sequences for ACTH, gamma-LPH, beta-MSH and beta-endorphin(More)
Zebrafish is a novel experimental model that has been used in developmental studies as well as in the study of pathological processes involved in human diseases. It has been demonstrated that the endogenous opioid system is involved in developmental mechanisms. We have studied the relationship between the different embryonic stages and opioid receptor(More)
The use of cocaine during pregnancy can affect the mother and indirectly might alter the development of the embryo/foetus. Accordingly, in the present work our aim was to study in vivo (in zebrafish embryos) the effects of cocaine on the expression of dopamine receptors and on miR-133b. These embryos were exposed to cocaine hydrochloride (HCl) at 5 hours(More)
Opioid receptors, besides mediating the effects of analgesic compounds, are involved in drug addiction. Although a large amount of work has been done studying these receptors in mammals, little information has been obtained from nonmammalian vertebrates. We have studied the regional distribution in the central nervous system (CNS) of the zebrafish of the(More)
The functional characterization of the mu opioid receptor from the zebrafish (zfMOR) is reported here. After transfection in HEK-293 cell line, using both peptidergic and nonpeptidergic opioid ligands in the competition and saturation-binding experiments, in addition to the functional assays of (35)S-GTPgammaS-binding assays and intracellular 3'-5'-cyclic(More)