Laparoscopic procedures impact on mast cell mediators, extracellular matrix and adhesion scoring system in rats

Background

Laparoscopic procedures under certain pressure have the potential to cause intra-abdominal adhesions. However, the pathomechanism of this disorder is unknown. Release of mast cell mediators due to mast cell degranulation is thought to be the cause.

Materials and methods

Thirty male Sprague-Dawley rats were grouped into five groups (n = 6 per group): one control group and four intervention groups to which 60 min insufflation was performed using carbon dioxide at 5, 8, 10 and 12 mmHg. Seven days after laparoscopy, we euthanized and evaluated the levels of histamine, tryptase, and chymase of peritoneal fluid, the thickness of ECM of peritoneal tissue, and intraabdominal adhesion scoring system.

Results

Histamine and tryptase levels in peritoneal fluid were significantly higher at the 10- and 12 mm Hg intervention compared to control (histamine: 0.50 ± 0.35 vs. 0.41 ± 0.41 vs. 0.04 ± 0.02 ng/mL, respectively; and tryptase: 0.69 ± 0.11 vs. 0.65 ± 0.05 vs. 0.48 ± 0.02 ng/ml respectively). The ECM was significantly thicker in the intervention groups at 10- and 12-mm Hg compared to control (71.3 [66.7–85.2] vs. 48.4 [34.5–50.3] vs. 10.25 [8.7–12.1] μm, respectively). Moreover, the intra-abdominal scoring was also significantly higher in the intervention groups at 10- and 12 mm Hg compared to control (4 [0–4] vs. 4.5 [4–5], vs. 0, respectively).

Conclusions

Laparoscopic procedures increase the release of mast cell mediators in peritoneal fluid, the thickness of ECM and intraabdominal adhesion scoring in rats, implying that it might increase the possibility of intrabdominal adhesion in humans.

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Laparoscopic procedures at specific pressures potentially cause intra-abdominal adhesion, however, its pathomechanism is still challenging to understand.

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Laparoscopic procedures increase the release of mast cell mediators in peritoneal fluid, the thickness of ECM and intraabdominal adhesion scoring in rats.

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Our findings imply that laparoscopic procedures might increase the possibility of intrabdominal adhesion in humans.

Activation of autophagy via Ca(2+)-dependent AMPK/mTOR pathway in rat notochordal cells is a cellular adaptation under hyperosmotic stress

Nucleus pulposus (NP) cells experience hyperosmotic stress in spinal discs; however, how these cells can survive in the hostile microenvironment remains unclear. Autophagy has been suggested to maintain cellular homeostasis under different stresses by degrading the cytoplasmic proteins and organelles. Here, we explored whether autophagy is a cellular adaptation in rat notochordal cells under hyperosmotic stress. Hyperosmotic stress was found to activate autophagy in a dose- and time-dependent manner. SQSTM1/P62 expression was decreased as the autophagy level increased. Transient Ca(2+) influx from intracellular stores and extracellular space was stimulated by hyperosmotic stress. Activation of AMPK and inhibition of p70S6K were observed under hyperosmotic conditions. However, intercellular Ca(2+) chelation inhibited the increase of LC3-II and partly reversed the decrease of p70S6K. Hyperosmotic stress decreased cell viability and promoted apoptosis. Inhibition of autophagy led to SQSTM1/P62 accumulation, reduced cell viability, and accelerated apoptosis in notochordal cells under this condition. These evidences suggest that autophagy induction via the Ca(2+)-dependent AMPK/mTOR pathway might occur as an adaptation mechanism for notochordal cells under hyperosmotic stress. Thus, activating autophagy might be a promising approach to improve viability of notochordal cells in intervertebral discs.