Tyramine's modulation of immune resistance functions in Litopenaeus vannamei and its signal pathway.

Tyramine (TA), a neuroactive chemical, plays various important physiological roles in insects by activating distinct G-protein-coupled receptors (GPCRs). In this study, we investigated the effects of by pharmacological injection of TA on immune resistance regulation and its signal pathway in white shrimp Litopenaeus vannamei. Results showed significant increases in the total haemocyte count (THC), semigranular cells (SGCs), granular cells (GCs), phenoloxidase (PO) activity per 50 µL of haemolymph and respiratory bursts (RBs) at 0.5, 1, 2 and/or 4 h; hyaline cells (HCs) at 0.5 h, as well as phagocytic activity (PA) and clearance efficiency (CE) at 2, 4 and/or 8 h, but significantly decreased PO activity per granulocyte at 0.5-2 h for shrimp injected with TA at 100 and 1000 pmol shrimp-1. Plasma lysozyme activities of TA-injected shrimp were significantly higher than those of the saline control at 1 h. All of the immune parameters had returned to control levels by 8 h after receiving TA except the clearance efficiency, which had returned to its control value by 16 h. The TA injection also significantly decreased the mortality of shrimp challenged with Vibrio alginolyticus. Furthermore, immune parameters of shrimp that received TA at 1000 pmol shrimp-1 for 1 h were higher than those of shrimp that received the saline. The upregulating effect of TA was blocked by co-injection with phentolamine (Phe) in terms of the THC, HC, SGCs, PO activity, PA and CE; by co-injection with prazosin (Pra) in terms of the THC, HC, SGCs, PO activity, PA and CE; by co-injection with propranolol (Prop) in terms of the PA and CE; and by co-injection with metoprolol (Meto) in terms of the THC and SGCs. The most potent effect in immunocompetence of tested antagonists was Pra, and except for circulating haemocyte, it was Phe. These results suggest that ≤1000 pmol shrimp-1 of a TA injection mediates transient upregulation of immunity, which in turn promotes the resistance of L. vannamei to V. alginolyticus, and the active effects are mediated via octopamine/tyramine (OA/TA) receptors.

Antibodies to Multiple Receptors are Associated with Neuropsychiatric Symptoms and Mortality in Alzheimer's Disease: A Longitudinal Study.

BACKGROUND: Endogenous antibodies to signaling molecules and receptors (Abs) are associated with Alzheimer's disease (AD). OBJECTIVES: To investigate the association of 33 Abs to dopaminergic, serotoninergic, muscarinic, adrenergic, vascular, and immune receptors with cognitive, neuropsychiatric, and mortality outcomes. METHODS: Ninety-one patients with mild AD were followed annually for 5 years with the Mini-Mental State Examination (MMSE) and the Neuropsychiatric Inventory (NPI; composite outcomes: "psychosis" (item 1 + 2), "mood" (item 4 + 5 + 7), and "agitation" (item 3 + 8 + 9)). Abs were quantified in sera obtained at baseline by ELISA and reduced to principal components (PCs). Associations between Abs and outcomes were assessed by a mixed model (MMSE decline), zero-inflated fixed effects count models (composite NPI scores), and Cox regression (mortality). The resulting p-values were adjusted for multiple testing according to a false discovery rate of 0.05 (Benjamini-Hochberg). RESULTS: The measured levels of the 33 Abs formed four PCs. PC1 (dopaminergic and serotonergic Abs) was associated with increased mortality (Hazard ratio 2.57, p < 0.001), PC2 (serotonergic, immune, and vascular Abs) with decreased agitation symptoms (ß - 0.19, p < 0.001), and PC3 (cholinergic receptor Abs) with increased mood symptoms (ß 0.04, p = 0.002), over time. There were no associations between Abs and MMSE decline. CONCLUSION: The associations between Abs, mortality, and neuropsychiatric symptoms reported in this cohort are intriguing. They cannot, however, be generalized. Validation in independent sample sets is required.

Developmental expression analysis and immunolocalization of a biogenic amine receptor in Schistosoma mansoni.

A Schistosoma mansoni G-protein coupled receptor (SmGPCR) was previously cloned and shown to be activated by the biogenic amine, histamine. Here we report a first investigation of the receptor's subunit organization, tissue distribution and expression levels in different stages of the parasite. A polyclonal antibody was produced in rabbits against the recombinant third intracellular loop (il3) of SmGPCR. Western blot studies of the native receptor and recombinant protein expressed in HEK293 cells showed that SmGPCR exists both as a monomer (65 kDa) and an apparent dimer of approximately 130 kDa These species were verified by immunoprecipitation of SmGPCR from S. mansoni extracts, using antibody that was covalently attached to agarose beads. Further investigation determined that the SmGPCR dimer was resistant to treatment with various detergents, 4 M urea and 0.1 M DTT but could be made to dissociate at acidic pH, suggesting the dimer is non-covalent in nature. Confocal immunofluorescence studies revealed significant SmGPCR immunoreactivity in sporocysts, schistosomula and adult worms but not miracidia. SmGPCR was found to be most widely expressed in the schistosomula, particularly the tegument, the subtegumental musculature and the acetabulum. In the adult stage we detected SmGPCR immunofluorescence mainly in the tubercles of male worms and, to a lesser extent, the body wall musculature. Localization in sporocysts was mainly confined to the tegument and cells within parenchymal matrices. A real-time quantitative reverse-transcription PCR analysis revealed that SmGPCR is upregulated at the mRNA level in the parasitic stages compared to the free-living miracidium and cercariae, and it is particularly elevated during early sporocyst and schistosomula development. The results identify SmGPCR as an important parasite receptor with potential functions in muscle and the tegument of S. mansoni.