[The types of respiratory neurons in nucleus paragigantocellularis lateralis in rats and their responses to some medicines].

AIM AND METHODS

In 36 anesthetized spontaneously breathing Sprague-Dawley rats, the types of respiratory neurons and the state of neurotransmitters and receptors in nucleus paragigantocellularis lateralis (PGCL) were studied with extracellular recording technique and multibarrel microelectrode techniques.

RESULTS

At the caudal part of the PGCL(cPGCL) in 14 rats, a total of 39 respiratory neurons (RNs) were recorded including 24 inspiratory, 12 expiratory and 3 phase-spanning neurons. At the cPGCL in another 22 rats, we discovered that out of 14 RNs tested, 12 were excited by iontophoretic application of sodium glutamate (L-GLu), and all the 22 RNs tested were inhibited by gamma-aminobutyric acid (GABA). DL-2-amino-5-phosphonovaleric acid (AP5), an antagonist of N-methyl-D-aspartate (NMDA) receptor, and bicuculline (BIC), an antagonist of GABA(A) receptor, both showed three kinds of effects on the RNs discharge: excitatory, inhibitory and no-effect. AP5 could block partially the excitatory effect of L-GLu on a large part of RNs tested (6/9). BIC blocked, partially or completely, the inhibitory effect of GABA also on a large part of the RNs tested (9/11).

CONCLUSION

It is implied that PGCL is one of the important neural substrates responsible for the regulation of respiration. There might exist endogenous glutamate and GABA acting as neurotransmitters in the cPGCL area and excitatory amino acids (including NMDA and non- NMDA) and GABA(A)-receptors on cPGCL neurons. These neurotransmitters and receptors may mediate the regulatory action of cPGCL on respiration.