- Email: [email protected]
1412 A peptide which has neurotrophic factor-like activities
S149 1 41 1
SYNAPTIC P L A S T I C I T Y I N V O L V I N G RAPID S Y N A P T O G E N E S I S IN S Y M P A T H E T I C G A N G L I O N . Y O S H I N O R I K A W A I A N D EMIKO SENBA, Depart. Anat., Wakayama Medical College, 27 Kubancho, Wakayama 640, Japan.
W e previously demonstrated that some superior cervical ganglion (SCG) neurons could play a role o f local circuit neurons by employing their dendrites as presynaptic elements, and that such local circuitry undergoes dynamic morphological plasticity. In normal condition, most SCG neurons play merely a role o f relay neurons, while, hyperpolarizing conditionings (bath application o f noradrenaline or intmcellular injection of hyperpolarizing currents) initiate a rapid formation of adrenergic synapses wiihin the ganglion. The present study was designed to examine electrophysiologically how these de n o v o constructed synapses could participate in a modulation of the ganglionic transmission. Suprathreshold repetitive stimulation o f the cervical sympathetic trunk elicited a hyperpolarizing response lasting for more than 1 see from SCG neurons after the hyperpolarizing conditioning. T h e characteristics o f the response were very similar to those of cx2-adrenergic inhibitory postsynaptic potentials. T h e s e findings suggest that hyperpolarizing conditioning of the SCG causes a formation of inhibitory local circuitry within the ganglion in which a mechanism of negative feedback against ongoing sympathetic activation might take place.
1412
A PEPTIDE WHICH HAS NEUROTROPHIC FACTOR-LIKE ACTIVITIES MARIKO ISHIGURO, MIYUKI MURAYAMA, *AKIRA OOMORI, TOKIKO HAMA Dept. of Neurosci., *Lab. of Biopol. Conform. Anal., Mitsubishi Kasei Institute of Life Sciences, 11 Minamiooya, Machida-shi, Tokyo 194, Japan
Neuronal deveropment, survival and repairment from injury are supported by several factors. One of these factors is a neurotrophic factor. Recently some neurotrophie factors have been reported to exist and be secreted in central nervous system. We have studied about neurotrophic factors which support neuronal survival using primary cultured from about 2week-old rat brain and purified neurotrophic factors from gelform which was implanted in brain cortex cavity. For the analysis of molecular conformation of these factors, we have obtained some peptides by trypsin digestion. According to the sequence of one of these peptide which consist of 13 amino acids was synthesized. This peptide supported the survival of septal cholinergic neurons and mesencephalic dopaminergic neurons in primary cultures.
a 413
ANOblAI.OUSc-Fos INDUCTION IN TIlE DENERVATEDTIBIALTERRITORYOF TIIE DORSAl. IIORN BY TIlE PERONEALSTIblUIakqION. TOIMOSADA~SU_GISAOT_O_ 1, _ttlROXU.KI.ICIUlGXWAI_A_NDSEIJLSAIT_ANL 2, 1Second_i/ept~o£ _.Oral An atomy_and2Dc pt ,_gf__Orthodon_tics,_Okayama_lJ.nivcrsity D ental~cho ol, 27.-5-_LShikat a clm,.OJatyama_700._
Subcutaneous formalin injection into the hind paw of rats induces c-Fos expression in neurons in the ipsilateral spinal dorsal horn within 2 hours. In laminae I and II of the dorsal horn at the junction of 4th and 5th segments of the lumbar spinal cord, neurons exhibiting "c-Fos protein-like immunoreactivity (Fos neurons) are concentrated in the medial 3/4 that correspond to the terminal field of primary neurons innervating the sciatic nerve. Subacute tibial nerve section 24 h before formalin stimulation caused almost complete elimination of the formalin-induced Fos neuron in the medial 1/2 (tibial territory) of the above sciatic territory of the dorsal horn. Following a longer survival period (chronic tibial nerve section of 21 days standing), formalin-induced Fos neurons re-appeared in the tibial territory. In addition, the number of Fos neurons increased in the medial part of the peroneal territory (the lateral 1/2 of the sciatic territorT). The results indicate that the activation of c-Fos expression in that part of dorsal horn that has been chronically deafferented by the tibial nerve section is taken over by the spared, but somatotopically inappropriate primary nociceptors. "lhe anomalous c-Fos induction can be detected at the post-transectional survival period of 2 weeks or longer.
SYNAPTIC P L A S T I C I T Y I N V O L V I N G RAPID S Y N A P T O G E N E S I S IN S Y M P A T H E T I C G A N G L I O N . Y O S H I N O R I K A W A I A N D EMIKO SENBA, Depart. Anat., Wakayama Medical College, 27 Kubancho, Wakayama 640, Japan.
W e previously demonstrated that some superior cervical ganglion (SCG) neurons could play a role o f local circuit neurons by employing their dendrites as presynaptic elements, and that such local circuitry undergoes dynamic morphological plasticity. In normal condition, most SCG neurons play merely a role o f relay neurons, while, hyperpolarizing conditionings (bath application o f noradrenaline or intmcellular injection of hyperpolarizing currents) initiate a rapid formation of adrenergic synapses wiihin the ganglion. The present study was designed to examine electrophysiologically how these de n o v o constructed synapses could participate in a modulation of the ganglionic transmission. Suprathreshold repetitive stimulation o f the cervical sympathetic trunk elicited a hyperpolarizing response lasting for more than 1 see from SCG neurons after the hyperpolarizing conditioning. T h e characteristics o f the response were very similar to those of cx2-adrenergic inhibitory postsynaptic potentials. T h e s e findings suggest that hyperpolarizing conditioning of the SCG causes a formation of inhibitory local circuitry within the ganglion in which a mechanism of negative feedback against ongoing sympathetic activation might take place.
1412
A PEPTIDE WHICH HAS NEUROTROPHIC FACTOR-LIKE ACTIVITIES MARIKO ISHIGURO, MIYUKI MURAYAMA, *AKIRA OOMORI, TOKIKO HAMA Dept. of Neurosci., *Lab. of Biopol. Conform. Anal., Mitsubishi Kasei Institute of Life Sciences, 11 Minamiooya, Machida-shi, Tokyo 194, Japan
Neuronal deveropment, survival and repairment from injury are supported by several factors. One of these factors is a neurotrophic factor. Recently some neurotrophie factors have been reported to exist and be secreted in central nervous system. We have studied about neurotrophic factors which support neuronal survival using primary cultured from about 2week-old rat brain and purified neurotrophic factors from gelform which was implanted in brain cortex cavity. For the analysis of molecular conformation of these factors, we have obtained some peptides by trypsin digestion. According to the sequence of one of these peptide which consist of 13 amino acids was synthesized. This peptide supported the survival of septal cholinergic neurons and mesencephalic dopaminergic neurons in primary cultures.
a 413
ANOblAI.OUSc-Fos INDUCTION IN TIlE DENERVATEDTIBIALTERRITORYOF TIIE DORSAl. IIORN BY TIlE PERONEALSTIblUIakqION. TOIMOSADA~SU_GISAOT_O_ 1, _ttlROXU.KI.ICIUlGXWAI_A_NDSEIJLSAIT_ANL 2, 1Second_i/ept~o£ _.Oral An atomy_and2Dc pt ,_gf__Orthodon_tics,_Okayama_lJ.nivcrsity D ental~cho ol, 27.-5-_LShikat a clm,.OJatyama_700._
Subcutaneous formalin injection into the hind paw of rats induces c-Fos expression in neurons in the ipsilateral spinal dorsal horn within 2 hours. In laminae I and II of the dorsal horn at the junction of 4th and 5th segments of the lumbar spinal cord, neurons exhibiting "c-Fos protein-like immunoreactivity (Fos neurons) are concentrated in the medial 3/4 that correspond to the terminal field of primary neurons innervating the sciatic nerve. Subacute tibial nerve section 24 h before formalin stimulation caused almost complete elimination of the formalin-induced Fos neuron in the medial 1/2 (tibial territory) of the above sciatic territory of the dorsal horn. Following a longer survival period (chronic tibial nerve section of 21 days standing), formalin-induced Fos neurons re-appeared in the tibial territory. In addition, the number of Fos neurons increased in the medial part of the peroneal territory (the lateral 1/2 of the sciatic territorT). The results indicate that the activation of c-Fos expression in that part of dorsal horn that has been chronically deafferented by the tibial nerve section is taken over by the spared, but somatotopically inappropriate primary nociceptors. "lhe anomalous c-Fos induction can be detected at the post-transectional survival period of 2 weeks or longer.