Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCB294

Poster Communications

Activation of 5-HT4 receptors induced a lower extent of cell proliferation and differentiation in spinal cord and hippocampus of postnatal mice

N. Ghani1, K. Greenin1, G. Ford1, J. Deuchars1, S. Deuchars1

1. University of Leeds, Leeds, United Kingdom.

Neurogenic niches have been identified in the hippocampus and subventricular zone (Seaberg and van der Kooy 2002; Lois and Alvarez-Buylla 1994). There is also evidence that the central canal area is a neurogenic niche with ependymal cells having characteristics of self-renewal, multilineage capability and clonogenic efficiency (Barnabé-Heider et al. 2010). However the ability of certain neurotransmitters to control cell proliferation is still unknown. Since 5-HT4 receptors have been shown to modulate cell proliferation and differentiation in the enteric nervous system (Liu et al. 2009), the effects of a 5-HTR4 agonist on the proliferative ability of cells spinal cord were examined. C57BI/6 mice (6-8 week,n=8) were injected with Tegaserod maleate (5-HTR4 agonist, 1mg/kg) or saline and the thymidine analogue 5-ethynyl-2'-deoxyuridine (EdU, 10mM) for 7 days. One week after the last injection, the mice were anaesthetized (60mg/kg sodium pentobarbitone) and perfused transcardially with 4% paraformaldehyde. Cervical, sacral spinal cord and hippocampus regions were removed and sectioned (50µm) and detection for EdU was performed and followed by immunofluorescence for differentiation markers for astrocytes, oligodendrocytes and neurones. In the dorsal region of the dentate gyrus, Tegaserod group had significantly fewer proliferating cells, (32.6±1.0, p<0.05) compared to the control group (40.3±2, p<0.05). Furthermore there was a reduction in the percentage colocalisation of EdU and the neuronal marker HuC/D in treatment group (8.8%±0.8 vs13.7%±1.2,p<0.05). EdU+ve cells were counted in central canal, grey matter and white matter of the spinal cord. Tegaserod-treated mice had lower numbers of proliferating cells in specific regions of spinal cord compared to control. Overall in cervical regions there were fewer proliferating cells in Tegaserod-treated mice compared with control (79±8.8vs102.5±8.2,p<0.05). Furthermore the central canal had fewer proliferating cells compared to control group (4.4±1.4vs7.8±1.3,p<0.05). However there were no significant differences in the numbers of EdU+ve cells between Tegaserod-treated and control mice in either gray matter or white matter. In sacral spinal cord, Edu+ve cells were significantly fewer in all regions including white matter (19.6±1.4vs30.5±3.6,p<0.05), gray matter (28.3±2.0vs47.4±4.5,p<0.05) and central canal (5.5±0.9vs9.8±1.2,p<0.05) in treatment group compared to control. The percentages of differentiation markers were determined and there were no significant difference between groups for all markers. In conclusion, activation of 5-HTR4 reduced the extent of cell proliferation generally and the differentiation into neurones specifically in hippocampus. It might suggest this activation can help in reducing the rate of cell proliferation in cancerous conditions.

Where applicable, experiments conform with Society ethical requirements