J. Neurochem. (2012) 121, 428–437. Abstract The impact of Regulated upon Activation Normal T cells Expressed and Secreted (RANTES) on the release of pre‐loaded [3H]d‐aspartate ([3H]d‐ASP) from mouse spinal cord synaptosomes was investigated. RANTES (0.01–1 nM) failed to affect the spontaneous release, but facilitated the 15 mM K+‐evoked overflow of [3H]d‐ASP. Incubation of synaptosomes with antibodies raised against the chemokine receptor (CCR)1 and CCR5 proteins prevented RANTES‐induced facilitation of glutamate exocytosis, whereas anti‐CCR3 antibody was inefficacious. Accordingly, BX513 and d‐Ala‐peptide T‐amide (DAPTA) CCR1 and CCR5 antagonists, respectively, prevented RANTES‐induced effect, whereas the CCR3 antagonist SB 328437 was inactive. To compare these findings to previous results, we quantified the effects of CCR antagonists on the RANTES‐induced modifications of the spontaneous and the K+‐evoked [3H]d‐ASP release in the mouse cortex. Here, CCR1 and CCR5, but not CCR3, antagonists prevented the RANTES‐mediated [3H]d‐ASP release, whereas RANTES‐induced inhibition of the 12 mM K+‐evoked [3H]d‐ASP exocytosis was also antagonized by SB 328437. Facilitation of glutamate exocytosis in spinal cord relied on PLC‐dependent mobilization of Ca2+ from IP3‐sensitive stores; adenylyl cyclase was not involved. CCR1, CCR3 and CCR5 receptor proteins were present in spinal cord synaptosomal and gliosomal lysates, although RANTES‐induced changes to glutamate release could not be observed in gliosomes. Our results confirm the role of RANTES as modulator of glutamate transmission.

Novel drug delivery systems targeting native, transplanted, or cancerous beta-cells are of utmost importance. Herein, we present new exendin-4 derivatives with modified unnatural amino acids at strategic positions within the polypeptide sequence. The modified peptides allowed modular orthogonal chemical modifications to attach imaging agents and amphiphilic squalene-PEG groups. The resulting conjugates, SQ-PEG-ExC-Cy5 and SQ-PEG-ExC-Cy5 fluorescence probes, display low nanomolar affinity to GLP-1R in fluorescence-based binding assays with EC at 1.1 ± 0.2 and 0.8 ± 0.2 nM, respectively. Naturally expressing GLP-1R MIN6 cells and recombinantly transfected CHL-GLP-1R positive cells were specifically targeted by all of the new beta-cell probes in vitro. Specific islet targeting was observed after i.v. injection of SQ-PEG-ExC-Cy5 with SQ-PEG in normoglycemic mice ex vivo. Semiquantitative biodistribution analysis by epifluorescence indicated prolonged blood half-life (3.8 h) for the amphiphilic Ex conjugate. Liver and pancreas were identified as main biodistribution organs for SQ-PEG-ExC-Cy5.