Diabetes mellitus influences the expression of NPY and VEGF in neurons of rat trigeminal ganglion.
BACKGROUND
Diabetes mellitus (DM) influences the trigeminal nerve function by changing the pain response and transduction of the orofacial sensory pathways. It affects the inflammatory response via neuropeptide Y (NPY) and vascular endothelial growth factor (VEGF), which could potentially have a relevant role in the pathophysiology of diabetic neuropathy. The aim was to investigate expression of VEGF and NPY in subpopulations of trigeminal ganglion (TG) neurons in rat models of early DM1 and DM2.


METHODS
DM1 model was induced by an intraperitoneal (i.p.) injection of streptozotocin (STZ) (55mg/kg). DM2 rats were fed with a high fat diet (HFD) for two weeks and then received 35mg/kg of STZ i.p. Two weeks and 2months after the STZ-diabetes induction, rats were sacrificed and TG was immunohistochemically analyzed for detection of VEGF and NPY expression, and also double immunofluorescence labeling with isolectin (IB4) was completed.


RESULTS
An increased percentage of NPY+ neurons was observed 2weeks after DM1 and 2months post DM2 induction. NPY immunoreactivity was restricted to IB4-negative small-diameter and IB4+ neurons. Two weeks post induction, DM1 rats showed an increased percentage of VEGF/IB4- large neurons and DM2 rats showed an increased percentage of VEGF/IB4+ neurons. Two months after DM induction, the DM1 group showed a reduced percentage of VEGF/IB4- small neurons.


CONCLUSIONS
The observed changes may play a critical role in the modulation of nociceptor activity and plasticity of primary sensory trigeminal neurons. The results contribute to the understanding of the basic pathophysiology of trigeminal diabetic neuropathy.
University of Split, School of Medicine, Department of Anatomy, Histology and Embryology, Laboratory for Neurocardiology, Croatia.
Milka
M
Jerić
University of Split, School of Medicine, Department of Anatomy, Histology and Embryology, Laboratory for Neurocardiology, Croatia; University of Split, School of Medicine, Department of Anatomy, Histology and Embryology, Laboratory for Early Human Development, Croatia.
Katarina
K
Vukojević
University of Split, School of Medicine, Department of Anatomy, Histology and Embryology, Laboratory for Neurocardiology, Croatia.
Ana
A
Vuica
University of Split, School of Medicine, Department of Anatomy, Histology and Embryology, Laboratory for Neurocardiology, Croatia. Electronic address: natalija.filipovic@mefst.hr.
Natalija
N
Filipović
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D004195:Disease Models, Animal; D008297:Male; D009474:Neurons / Q000378:metabolism*; D009478:Neuropeptide Y / Q000378:metabolism*; D017207:Rats, Sprague-Dawley; D012668:Trigeminal Ganglion / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
D009478:Neuropeptide Y; D042461:Vascular Endothelial Growth Factor A
Diabetes mellitus; Isolectin B4; NPY; Trigeminal neuropathy; VEGF