PROJECTIONS OF CALBINDIN D-28K-LIKE,SUBSTANCE P RECEPTOR AND Fos-POSITIVE NEURONS FROM THE LUMBEAR SPINAL CORD TO THE LATERAL PARABRACHIAL NUCLEUS OF THE RAT / 解剖学报

ABSTRACT

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.