BACKGROUND: Nitric oxide synthase(NOS) is extensively distributed in the central nervous system and modulates neuronal activities. However,there are few reports about NOS' s involvement in nociceptive information transmission at the supraspinal level.OBJECTIVE: To investigate the relation between the primary afferent visceral terminials and the NOS-containing neurons which project from the interstitial nucleus of spinal trigeminal tract(INV) to the parabrachial nucleus(PBN).DESIGN: A controlled experimental observation based on the experimental animals.SETTING: Department of anatomy in a military medical university of Chinese PLA.MATERIALS: The experiment was conducted in the Department of Anatomy,Fourth Military Medical University of Chinese PLA,from January to December 2002. Ten adult male SD rats were selected in this experiment.INTERVENTIONS: Tetramethyl rhodamine-dextran(TMR) and biotinylated dextran-amine(BDA) were injected into the PBN and vago-glossopharyngeal nerves respectively combining with the immunohistochemical method for NOS and the observation with laser confocal scanning microscope.MAIN OUTCOME MEASUREES: Overlapping of TMR retrogradely labeled neurons,NOS positive labeled neurons and transganglionic tracing labeled terminals,and their relationship in INV.RESULTS: After injection of TMR into the PBN,the retrogradely labeled neurons,mostly small and medium-sized(below20 μm),were found in the INV ipsilateral to the injection side. The distribution of the NOS positive neurons overlapped with retrogradely labeled neurons in INV. The proportion of the number of double-labeled neurons with NOS/TMR was 55% (17/31)and 34% (17/49) in the whole population of the NOS positive neurons and retrogradely neurons,respectively. Some transganglionic tracing labeled terminals after BDA injection had close contact with the double-labeled neurons.CONCLUSION: The visceral nociceptive pathway exists from INV to PBN and NO may act as the transmitter or neural signal molecule in the transmission and regulation of visceral nociceptive process.

Objective To observe the relationships among the direct projection neurons from the lumbar spinal cord to the lateral parabrachial nucleus(LPB),calbindin D-28K(CB)-like immunoreactive (-LI) neurons,peripheral noxious information transmission as well as substance P receptor(SPR)-LI neurons. Methods Triple-labeled techniques were used by tetramethyl rhodamine(TMR) retrograde tracing combined with immunofluorescence histochemistry for CB-,SPR- or Fos protein.The stained sections were observed under a confocal laser-scanning microscope. Results 1.After injecting TMR to the unilateral LPB,a number of TMR retrogradely labeled neurons were mainly distributed in the lamina Ⅰ,lateral spinal nucleus(LSN),and regions around the central canal of the spinal cord(lamina X) of the ipsilateral spinal cord;2.CB-LI neurons were mainly found in the laminae Ⅰ and Ⅱ of the lumbar spinal cord,especially in the lamina Ⅱ in the dense distribution; 3.SPR-LI neurons were also mainly seen in the lamina Ⅰ,LSN and lamina X of the spinal cord.A few of the SPR-LI neurons were also distributed in the lamina Ⅱ;4.Fos-positive neurons were detected in the laminae Ⅰ and Ⅱ,lateral aspect of the lamina Ⅴ to Ⅶ of the lumbar spinal cord by injecting 5% formalin into the ipsilateral hindpaw;5.Triple-labeled neurons for TMR/CB/SPR or TMR/CB/Fos were mainly found in lamina Ⅰ,while a few of the triple-labeled neurons were also found in lamina Ⅱ of the dorsal horn.TMR/CB/SPR triple-labeled neurons accounted for 103%,98% and 146% of total population of TMR-,CB- or SPR-LI neurons in laminae Ⅰ and Ⅱ,respectively.On the other hand,TMR/CB/Fos triple-labeled neurons formed 118%,106% and 158% of the total population of TMR-,CB-LI or Fos-positive neurons in the laminae Ⅰ and Ⅱ,respectively.Conclusion\ The results indicated that in the laminae Ⅰ and Ⅱ of the lumbar spinal cord some neurons with CB-Like immunoreactivity transmitting the peripheral noxious information and projecting directly to the LPB might receive SPergic primary afferents.

Objective To examine the cardiac primary afferents passing through the superior cervical ganglion which the sensory neurons are located in the vagal ganglion. Methods Retrograde tracing transport combined with immunohistochemistry. Results After injecting the horseradish peroxidase(HRP) into the superior cervical ganglion in the rat, the small number of retrogradely labeled neurons consistently appeared in the upper local portion of the nodose ganglion. The same injecting of fluorogold(FG) followed by immunohistochemical staining with SP, it was found that the double\|labeled neurons with FG/SP were approximately 20% occupied the total population of the SP positive neurons in the nodose ganglion. Conclusions The present results, associated with previous reports, suggest that the pathway of the vagal afferent conveying cardiac pain information which contains SP pass through the superior cervical ganglion.\;[