ABSTRACT
RFamide neuropeptide VF (NPVF) is expressed by neurons in the hypothalamus and has been implicated in nociception, but the circuit mechanisms remain unexplored. Here, we studied the structural and functional connections from NPVF neurons to downstream targets in the context of nociception, using novel transgenic lines, optogenetics, and calcium imaging in behaving larval zebrafish. We found a specific projection from NPVF neurons to serotonergic neurons in the ventral raphe nucleus (vRN). We showed NPVF neurons and vRN are suppressed and excited by noxious stimuli, respectively. We combined optogenetics with calcium imaging and pharmacology to demonstrate that stimulation of NPVF cells suppresses neuronal activity in vRN. During noxious stimuli, serotonergic neurons activation was due to a suppression of an inhibitory NPVF-ventral raphe peptidergic projection. This study reveals a novel NPVF-vRN functional circuit modulated by noxious stimuli in vertebrates.
Subject(s)
Hypothalamus/metabolism , Neuropeptides/metabolism , Nociception , Raphe Nuclei/metabolism , Zebrafish/metabolism , Amino Acid Sequence , Animals , Neurons/metabolism , Neuropeptides/chemistry , Serotonin/metabolismABSTRACT
Neurons exhibit rhythmic activity that ultimately affects behavior such as sleep. In living zebrafish larvae, we used time-lapse two-photon imaging of the presynaptic marker synaptophysin in hypocretin/orexin (HCRT) neurons to determine the dynamics of synaptic modifications during the day and night. We observed circadian rhythmicity in synapse number in HCRT axons. This rhythm is regulated primarily by the circadian clock but is also affected by sleep deprivation. Furthermore, NPTX2, a protein implicated in AMPA receptor clustering, modulates circadian synaptic changes. In zebrafish, nptx2b is a rhythmic gene that is mostly expressed in hypothalamic and pineal gland cells. Arrhythmic transgenic nptx2b overexpression (hcrt:NPTX2b) increases synapse number and abolishes rhythmicity in HCRT axons. Finally, hcrt:NPTX2b fish are resistant to the sleep-promoting effects of melatonin. This behavioral effect is consistent with NPTX2b-mediated increased activity of HCRT circuitry. These data provide real-time in vivo evidence of circadian and homeostatic regulation of structural synaptic plasticity.
Subject(s)
Circadian Rhythm/physiology , Homeostasis/physiology , Intracellular Signaling Peptides and Proteins/metabolism , Neuronal Plasticity/physiology , Neurons/physiology , Neuropeptides/metabolism , Synapses/physiology , Animals , Animals, Genetically Modified , Axons/metabolism , Behavior, Animal , Brain/cytology , Brain/growth & development , C-Reactive Protein/genetics , C-Reactive Protein/metabolism , Circadian Rhythm/genetics , Gene Expression Regulation, Developmental/drug effects , Gene Expression Regulation, Developmental/genetics , Green Fluorescent Proteins/genetics , Homeostasis/genetics , Humans , In Vitro Techniques , Larva , Light , Melatonin/pharmacology , Microscopy, Confocal , Nerve Tissue Proteins/genetics , Nerve Tissue Proteins/metabolism , Neuronal Plasticity/genetics , Neurons/cytology , Orexins , Pineal Gland/growth & development , Pineal Gland/metabolism , Synapses/genetics , Synaptophysin/metabolism , ZebrafishABSTRACT
The aims of this multicentre, randomised phase III trial were to evaluate: (1) the role of levamisol (LEV); and (2) the role of folinic acid (FA), added to 5-fluorouracil (5FU) in the adjuvant treatment of colorectal cancer. Patients with histologically proven, radically resected stage II or III colon or rectal cancer were eligible. The study had a 2x2 factorial design with four treatment arms: (a) 5FU alone, (b) 5FU+LEV, (c) 5FU+FA, (d) 5FU+LEV+FA, and two planned comparisons, testing the role of LEV and of FA, respectively. From March 1991, to September 1998, 1327 patients were randomised. None of the two comparisons resulted in a significant disease-free (DFS) or overall (OAS) survival advantage. The hazard ratio (HR) of relapse was 0.89 (95% confidence intervals (CI): 0.73-1.09) for patients receiving FA and 0.99 (95% CI 0.80-1.21) for those receiving LEV; corresponding HRs of death were 1.02 (95% CI: 0.80-1.30) and 0.94 (95% CI 0.73-1.20). Nonhaematological toxicity (all grade vomiting, diarrhoea, mucositis, congiuntivitis, skin, fever and fatigue) was significantly worse with FA, while all other toxicities were similar. In the present trial, there was no evidence that the addition of FA or LEV significantly prolongs DFS and OAS of radically resected colorectal cancer patients.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Colorectal Neoplasms/drug therapy , Adult , Aged , Chemotherapy, Adjuvant , Colorectal Neoplasms/pathology , Colorectal Neoplasms/surgery , Disease-Free Survival , Female , Fluorouracil/administration & dosage , Humans , Leucovorin/administration & dosage , Levamisole/administration & dosage , Male , Middle Aged , Treatment OutcomeABSTRACT
PURPOSE: To evaluate the efficacy and toxicity of a sequential low-dose methotrexate (MTX) and 5-fluorouracil (5FU) regimen in the palliative treatment of patients with advanced colorectal cancer. PATIENTS AND METHODS: Enrolled in the study were patients with advanced colorectal cancer, refractory to 5FU + FA. Patients were treated with MTX 40 mg/m2 i.v. bolus d 1 and 8, 5FU 700 mg/m2 i.v. bolus d 2 and 9 (24 hours after MTX bolus). The cycle was repeated every 4 weeks. RESULTS: 48 patients entered the study, and 45 are evaluable. The overall response rate was 15% with 1 complete response and 6 partial responses. Eight patients obtained disease stabilization. Median time to progression was 9 months. Toxicity was mild. Grade 3 stomatitis was observed in 7 (15%) patients. CONCLUSIONS: Sequential MTX/5FU is a well tolerated regimen with mild antitumor activity in refractory advanced colorectal patients.
