## 4 Discussion
\begin{table}
\begin{tabular}{l c c c c} \hline \multirow{2}{*}{**Groups**} & \multicolumn{2}{c}{**Caspase-3 Immunolabeled Cells**} & \multicolumn{2}{c}{**COX-2 Immunostained Cells**} \\ \cline{2-5}  & **AR Region** & **SB Mucosa Region** & **AR Region** & **SB Mucosa Region** \\ \hline Controls & & & & \\ \hline Intact vehicle & 45.20 \(\pm\) 15.75 & 28.00 \(\pm\) 6.93 & 40.50 \(\pm\) 10.38 & 18.80 \(\pm\) 3.55 \\ PM\({}_{2.5}\) & 414.00 \(\pm\) 57.25 a & 178.00 \(\pm\) 17.13 c & 447.00 \(\pm\) 83.60 cd & 108.30 \(\pm\) 12.33 a \\ Reference—AX & & & & \\
250 mg/kg & 138.80 \(\pm\) 38.52 ab & 51.20 \(\pm\) 11.75 cd & 117.00 \(\pm\) 30.17 cd & 41.60 \(\pm\) 7.93 ab \\ Test substance—AJ & & & & \\
400 mg/kg & 132.20 \(\pm\) 35.14 ab & 50.80 \(\pm\) 14.30 cd & 108.80 \(\pm\) 15.73 cd & 36.60 \(\pm\) 12.65 ab \\
200 mg/kg & 189.80 \(\pm\) 62.07 ab & 75.00 \(\pm\) 17.62 cd & 181.40 \(\pm\) 81.49 cd & 53.40 \(\pm\) 13.23 ab \\
100 mg/kg & 302.40 \(\pm\) 37.14 ab & 88.20 \(\pm\) 25.90 cd & 313.60 \(\pm\) 23.79 cd & 79.00 \(\pm\) 10.03 ab \\ \hline \end{tabular} Values are presented as means \(\pm\) S.D. of 10 mice, measured in cells/mm\({}^{2}\). PM\({}_{2.5}\) refers to diesel particulate matter NIST 1650b: AX denotes ambrosol hydrochloride; AJ indicates a tractylodisk Rhizoma (root of _ATactyl_s _japonic_ Koidz. Actam) extracts; COX stands for cyclooxygenase; SB represents secondary bronchus mucosa; AR is alveolar septal; THSD is [PERSON]’s Honest Significant Difference test; DT3 is [PERSON]’s T3 test. Statistical significance is indicated as follows: \({}^{a}\)\(p<\) 0.01 compared with intact vehicle control by THSD test; \({}^{b}\)\(p<\) 0.01 compared with PM\({}_{2.5}\) control by THSD test; \({}^{c}\)\(p<\) 0.01 compared with intact vehicle control by DT3 test; \({}^{d}\)\(p<\) 0.01 compared with PM\({}_{2.5}\) control by DT3 test.  
\end{table} 
Table 3: Histomorphometrical analysis of left lobe lung tissue in mice with pulmonary injuries, either untreated or treated with PM\({}_{2.5}\). acteristics of mucus, which is essential for effective mucociliary clearance [51]. MUC5 AC and MUC5B are the primary secretory mucins involved [49,50]. Studies indicate that PM\({}_{2.5}\) induces the overexpression of these mucins, enhancing mucus production [49,50,52]. Neural control, via acetylcholine (ACh) and substance P, regulates serous gland secretions [49]. Substance P functions as a mediator in neurogenic inflammation, and its levels increase with PM\({}_{2.5}\) exposure in the airways [53,54,55]. Similarly, ACh levels increase with PM\({}_{2.5}\) exposure, functioning as a vascular relaxant related to inflammatory vascular permeability, although the vascular response to ACh is impaired in PM\({}_{2.5}\)-treated mice [2,3,56,57]. Consistent with previous findings, the levels of lung tissue serous secretagogues, Ach, and substance P were significantly elevated after a 10-day continuous oral supply of AJ (400-100 mg/kg). This increase corresponded with significant and dose-dependent reductions in the mRNA expressions of mucus production-related genes, MUC5B and MUC5 AC, relative to the PM\({}_{2.5}\) control. These findings were comparable to those seen with AX at 250 mg/kg. This suggests potent mucolytic expectorant activities, possibly through increased secretion of substance P and ACh, leading to serous secretagogue effects and suppression of MUC5 AC and MUC5B mRNA expressions, resulting in decreased mucin production under the conditions of the current analysis. AJ administration significantly reduced the expressions of MUC5 AC and MUC5B mRNA, indicating potent mucolytic expectorant effects through increased secretion of ACh and substance P [54,55]. ACh and substance P are the primary neurotransmitters involved in serous secretions, acting as serous secretagogues, particularly in goblet cells and acinar cells in the respiratory system. Therefore, the increases in ACh and substance P due to AJ and AX may have been induced by serous secretions and the dilution of mucous, which is elevated by PM\({}_{2.5}\) exposure.