Distribution Of Pkc¦Ã In The Central Nervous Mechanism Of Exploration

Protein kinase C(PKC),a Ca²⁺-activated phospholipid-dependent kinase,is thought to play important roles in controlling several cellular processes.PKC_γsubunit(PKC_γ) is an important member of the PKC family,yet we don't know much more about it.It is very important to understand its function in the nociceptive signaling transduction/modulation of the nervous system.The work is to investigate its function with different experiments,including four sections as follows:PARTâ… :To observe the localization of protein kinase C_γsubunit in rat nervous system.By using specific antibody against PKC_γwe investigated the distribution of protein kinase C_γsubunit(PKC_γ) in the rat nervous system.PKC_γ-containing neurons are widely located in the rat nervous system.Intensely and densely stained PKC_γimmunoreactive neurons were mainly observed in the cerebral cortex, hippocampus,amygdaloid complex,cerebellar cortex,ventral and dorsal cochlear nuclei,caudal spinal trigeminal nucleus and spinal dorsal horns.These results provide morphological evidence for the functional roles of PKC_γin the signaling transduction of the nervous system.PARTâ…¡:To investigate the projections of protein kinase C_γisoform(PKC_γ) immunoreactive neurons from the medullary and spinal dorsal horns to the nucleus raphe pallidus(NRP) in rat.The double labeling method of fluoro-gold(FG) retrograde tracing combined with intmunofluorescence histochemical staining for PKC_γwas used.After injecting FG into the NRP,FG retrogradely labeled neurons were found in laminaeⅠ～Ⅲof the medullary and spinal dorsal horns.PKC_γimmunoreactive neurons were mainly observed in the inner part of laminaâ…¡and the border region between laminaeâ…¡andâ…¢,while in laminaeâ… andâ…¢,only a few PKC_γimmunoreactive neurons were observed.Some FG-labeled neurons in laminaâ… of the medullary and laminaeⅠ～Ⅲof the spinal dorsal horn also exhibited PKC_γimmunoreactivity.The present results indicate that PKC_γcontaining neurons in the medullary and spinal dorsal horns project to the NRP,suggesting that PKC_γmight be involved in the transmission of nociceptive information from the medullary and spinal dorsal horns to the NRP.PARTâ…¢:To investigate the co-existence of PKC_γand calcium-binding proteins in neurons of the medullary dorsal hom of the rat.Immunofluorescence histochemical double-staining for PKC_γand CB,CR or PV was performed in the rat MDH.Most of the PKC_γ-,CB-,CR- and PV-like immunoreactive neurons were observed in laminaâ…¡, some of them were also encountered in laminaâ… and laminaâ…¢of the MDH. CB/PKC_γ,CR/PKC_γand PV/PKC_γco-existed neurons were also mainly found in the laminaâ…¡,while in the laminaâ… and laminaâ…¢,only a few CB/PKC_γCR/PKC_γand PV/PKC_γco-existed neurons were encountered.The co-exited neurons in the medullary dorsal horn might play important roles in the nociceptive modulation from the oro-facial region.PARTâ…£:To investigate the pain-related changes and possible function of PKC_γin the rat spinal dorsal horn following sciatic nerve axotomy.The density of protein kinase C_γimmunoreactivity in the dorsal horn following sciatic nerve transection was valued in different time after surgery,2,5,10,15,20,30,40,60 days later respectively. The value(light absorbance value) was analyzed by contrasting the contralateral side and ispilateral side with a computer-assisted imaging analysis system.Axotomy of sciatic nerve significantly increased protein kinase C_γimmunoreactivity in the contralateral superficial dorsal horn of the L4 and L5 segments 2 to 40 days after the transection.2 days later,immunoreactivity in contralateral side had changed significantly(t=3.12,P＜0.05).This value reached 1.89 folds higest in contralateral side 15 days later(t=4.85,P＜0.01),while after a period of 2 months it attenuated to the normal level(t=0.91,P＞0.05).These results indicate that persistent changes in protein kinase C_γcontributes to the sensitization of dorsal horn neurons,which lasted about 2 months,produced by peripheral neuropathy.