Edassery, S. | Search bioRxiv

bioRxiv2022

Relapse-like behavior and nAChR sensitization following intermittent access nicotine self-administration

ABSTRACTMany tobacco smokers consume nicotine intermittently, but the underlying mechanisms and neurobiological changes associated with intermittent nicotine intake are unclear. Understanding intermittent nicotine intake is a high priority, as it could promote therapeutic strategies to attenuate tobacco consumption. We examined nicotine intake behavior and neurobiological changes in male rats that were trained to self-administer nicotine during brief (5 min) trials interspersed with longer (15 min) drug-free periods. Rats readily adapted to intermittent access (IntA) SA following acquisition on a continuous access (ContA) schedule. Probabilistic analysis of IntA nicotine SA suggested reduced nicotine loading behavior compared to ContA, and nicotine pharmacokinetic modeling revealed that rats taking nicotine intermittently may have increased intake to maintain blood levels of nicotine that are comparable to ContA SA. After IntA nicotine SA, rats exhibited an increase in unreinforced responses for nicotine-associated cues (incubation of craving) and specific alterations in the striatal proteome after 7 days without nicotine. IntA nicotine SA also induced nAChR functional upregulation in the interpeduncular nucleus (IPN), and it enhanced nicotine binding in the brain as determined via [11C]nicotine positron emission tomography. Reducing the saliency of the cue conditions during the 5 min access periods attenuated nicotine intake, but incubation of craving was preserved. Together, these results indicate that IntA conditions promote nicotine SA and nicotine seeking after a nicotine-free period.

neuroscience↗

bioRxiv2021

Xenogeneic Fibroblasts Inhibit The Growth Of Breast And Ovarian Cancer Cell Lines In Co-Culture

Cell-based therapies cure some hematologic malignancies, although little information exists on solid cancer cell responses. The study objective was to test the hypothesis that xenogeneic fibroblasts can inhibit the growth of human cancer cell lines in vitro. Seven human cell lines (pancreatic cancer HPAF II; brain cancer U-87 MG; fibrosarcoma; ovarian cancer OVCAR3 and SKOV3; and breast cancer MCF7 and MDA-MB231) were co-cultured with two xenogeneic fibroblast cell lines (CV-1;monkey, Cercopithecus aethiops and DF-1; chicken, Gallus gallus) in a transwell culture system. Cancer cell proliferation was assessed colorimetrically. Different concentrations of breast and ovarian cancer cells were tested. Gene expression induced by DF-1 xenogeneic fibroblasts was assessed by RNAseq of MCF7 breast cancer cells. The proliferation of the majority of the cancer cell lines was altered by co-culture with xenogeneic fibroblasts. Cell proliferation was increased (4-17%) by CV-1; DF-1 increased brain cancer cell proliferation (16%), decreased breast and ovarian cancer cell growth (15 and 26% respectively) but did not affect fibrosarcoma and pancreatic cancer cells. When the initial cancer cell concentrations were lowered 4-fold, growth inhibition of breast and ovarian cancer increased more than 2-fold. DF-1 fibroblasts induced significant differential expression of 484 genes in MCF7 breast cancer cells; 285 genes were down-regulated and 199 genes were upregulated compared to control. Genes involved in the immune response were the major downregulated entities. RNAseq results were validated by qRT-PCR of 12 genes. The results show that xenogeneic fibroblasts can alter the growth and gene expression of cancer cells in vitro. This suggests a potentially novel investigational approach to the control of cancer cell growth.

cancer biology↗