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Perturbation of the endocannabinoid system can have profound effects on immune function and synaptic plasticity. Microglia are one of few cell types with a self-contained endocannabinoid system and are positioned at the interface between the immune system and the central nervous system. Past work has produced conflicting results with respect to the effects of pro-inflammatory conditions on the microglial endocannabinoid system. Thus, we systematically investigated the relationship between the concentration of two distinct pro-inflammatory stimuli, lipopolysaccharide and interferon gamma, on the abundance of components of the endocannabinoid system within microglia. Here we show that lipopolysaccharide and interferon gamma influence messenger RNA abundances of the microglial endocannabinoid system in a concentration-dependent manner. Furthermore, we demonstrate that the efficacy of different synthetic cannabinoid treatments with respect to inhibition of microglia nitric oxide release is dependent on the concentration and type of pro-inflammatory stimuli presented to the microglia. This indicates that different pro-inflammatory stimuli influence the capacity of microglia to synthesize, degrade, and respond to cannabinoids which has implications for the development of cannabinoid-based treatments for neuroinflammation., Competing Interests: Declaration of Competing Interest The authors have no conflict of interest to report., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Transactivation of the firefly luciferase-encoding vectors, pXP1 and pXP2, by the alpha isoform of CCAAT/enhancer-binding protein (C/EBP) is reported. Thus, these vectors are not 'promoterless' in every cellular context, and transactivation by C/EBP or a closely related factor should be considered as a possible explanation for the relatively high background levels of luciferase production that are occasionally observed after transfection of certain cells with these or other similar vectors.

In this communication we demonstrate that gene transfer methodology can be applied to study gene expression in intact retinal explant cultures. The appropriate enzyme activity is observed in extracts obtained after electroporation of embryonic day-10 chicken retina with plasmids containing the chloramphenicol acetyltransferase-encoding or beta-galactosidase-encoding reporter genes under transcriptional control by the Rous sarcoma virus long terminal repeat. Similar results are obtained using Ca.phosphate-mediated gene transfer. Moreover, it has been previously established that glucocorticoid hormones stimulate transcription of glutamine synthetase (Glns) mRNA in embryonic retina. We report here that, based on the results of gene transfer experiments with chimeric plasmids containing 5'-flanking DNA derived from the cloned chicken Glns-encoding gene (Glns), essential glucocorticoid response elements reside between approx. 1.3 kb and 2.5 kb upstream from the Glns transcription start point. These data show that transfection of explant cultures can provide a useful approach to the study of gene expression in complex systems.

Complementary DNA (cDNA) and genomic clones encoding chicken glutamine synthetase (Glns) have been isolated. The nucleotide (nt) sequence of the 2728-bp cDNA specifies a 91-nt 5' untranslated sequence, a 1119-nt open reading frame, and a 1518-nt 3' untranslated sequence that contains several A + T-rich regions but lacks a canonical endonucleolytic-cleavage/polyadenylation signal. Based on sequence analysis of the cloned gene, the Glns transcription unit spans 7.0 kb and contains seven exons.