Differential effects of glutamate receptor antagonists on dorsal horn neurons responding to colorectal distension in a neonatal colon irritation rat model

Table 1 Percentage attenuation of responses to graded CRD of LS neurons by AP-7 in control and CI rats

Dose	20 (%)	40 (%)	60 (%)	80 (mmHg%)
Controls
0.001 mmoL	25 (4/16)	25 (4/16)	25 (4/16)	25 (4/16)
0.01 mmoL	36.3 (4/11)	36.3 (4/11)	36.3 (4/11)	45.4 (5/11)
0.1 mmoL	41.6 (5/12)	50 (6/12)	58.3 (7/12)	75 (9/12)
1 mmoL	50 (8/16)	50 (8/16)	50 (8/16)	81.2 (13/16)
CI rats
0.001 mmoL	40 (6/15)	40 (6/15)	40(6/15)	40 (6/15)
0.01 mmoL	60 (6/10)	60 (6/10)	60 (6/10)	60 (6/10)
0.1 mmoL	81.8 (9/11)	81.8 (9/11)	81.8 (9/11)	81.8 (9/11)
1 mmoL	100 (9/9)	100 (9/9)	100 (9/9)	100 (9/9)

Denominators in parentheses indicate the total number of LS neurons treated with AP-7 and numerators indicate the number of neurons affected by AP-7 at the same dose level in control and CI rats. A drug effect is described as a change by more than 20% in the response to CRD after the drug was applied, compared to baseline response recorded before the use of drug.

Table 2 Percentage attenuation of responses to graded CRD of LS neurons by CNQX in control and CI rats

Dose	20 (%)	40 (%)	60 (%)	80 (mmHg%)
Controls
0.2 μmoL	23.5 (4/17)	23.5 (4/17)	23.5 (4/17)	23.5 (4/17)
2 μmoL	44.4 (4/9)	44.4 (4/9)	44.4 (4/9)	44.4 (4/9)
5 μmoL	50 (4/8)	62.5 (5/8)	62.5 (5/8)	62.5 (5/8)
10 μmoL	71.4 (5/7 )	75 (6/8)	75 (6/8)	75 (6/8)
CI rats
0.2 μmoL	45.4 (5/11)	45.4(5/11)	45.4 (5/11)	45.4 (5/11)
2 μmoL	77.8 (7/9)	77.8 (7/9)	77.8 (7/9)	77.8 (7/9)
5 μmoL	83.3 (5/6)	83.3 (5/6)	83.3 (5/6)	83.3 (5/6)
10 μmoL	100 (8/8 )	100 (8/8 )	100 (8/8 )	100 (8/8 )

Denominators in parentheses indicate the total number of LS neurons treated with CNQX and numerators indicate the number of neurons affected by CNQX at the same dose level in control and CI rats. The effect of CNQX on neuronal response to all intensities of CRD was more pronounced in CI rats than that in control rats. CNQX dose-dependently attenuated the CRD-evoked responses at all distention pressures in all 8 (100%) CI neurons.