Characteristics of the New Mast Cell-Rich Nodal Structure in the Rat Skin Surface.

Background: : Acupuncture, practiced for millennia, lacks a clear anatomical definition for acupoints. A prevailing theory suggests that acupoints overlap with skin areas with higher mast cell density. Skin spots stained with intravenously infused Evans blue (EB), indicative of neurogenic inflammation, have recently been posited as acupoints in rats. Objectives: : To demonstrate the concordance between EB-reactive skin spots and mast cell-enriched acupoints. Methods: : We employed staining and RNA-seq analysis to delineate the morphological characteristics and gene expression profiles of EB-reactive skin spots in rats. Results: : EB infusion revealed a novel nodal structure on the rat skin surface, visible to the naked eye, with dimensions of approximately 1 mm in both diameter and height. Around 30 such nodes were identified on one side of the abdominal area, spaced roughly 3 mm apart, excluding the linea alba. RNA-seq analysis indicated that the gene expression patterns within these nodes markedly differed from both non-nodal skin areas and lymph nodes. Histological examination using toluidine blue revealed a significantly greater mast cell count in the nodes than in non-nodal skin regions. Additionally, the nodes stained positively with Alcian blue and Hemacolor, reagents known to mark primo vascular tissues. Conclusion: : Our findings suggest that EB-reactive nodes are indeed rich in mast cells. Further research is warranted to establish these skin nodes as surface primo nodes.

[Mast cell and substance P are involved in the process of acupoint sensitization induced by acute gastric mucosal injury].

OBJECTIVE: To observe changes of mast cells (MCs) number and morphology, and substance P (SP) expression in Evans blue (EB) extravasated region around acupoint "Pishu" (BL 20) and "Weishu" (BL 21) after acute gastric mucosal injury (AGMI) so as to investigate the mechanism underlying visceral problems-induced acupoint activation. METHODS: Thirty adult Wistar rats were randomly divided into normal control (n = 15) and AGMI groups (n = 15). AGMI model was duplicated by perfusing the rats with 0.5 mol/L HCl (1 mL/100 g) after fasting for 20 h. Five hours after AGMI, the rats were treated by tail-intravenous injection of EB dye (5 mg/100 g, 50 mg/mL in normal saline) for inducing dye-plasma extravasation in the skin around BL 20, BL 21 regions, etc. at the back. The rats of the normal control group were treated with tail-intravenous injection of 0.9% NaCl. The skin and subcutaneous tissues (2 mmx 2 mm) of extravasated EB dye points (BL 20 or BL 21 region) and those 2 mm lateral to the extravasated EB dye points in the model group and the corresponding points in the normal control group were sampled (followed by fixing them in 4% paraformaldehyde), sectioned and stained by toluidine blue (for labeling MCs). The expression of SP in the extravasated EB dye skin and subcutaneous tissues was detected by immunohistochemistry (n = 5) and western blot (n = 5) respectively. The number of MCs in these samples was counted and the degranulation rate of MCs calculated. RESULTS: The total number of MCs and the number of degranulated MCs were significantly more in the EB extravasation points (corresponding to BL 20/BL 21 area) of AGMI group than those in the control spots of AGMI group and than those in the normal control group (P < 0.05, P < 0.001). The degranulation rate of MCs was significantly higher in the EB extravasation points of AGMI group than those in the control spots of AGMI group and in the normal control group (P < 0.01). In comparison with normal control group, the SP expression level was increased consideraly in the control spots of AGMI group and AGMI group (P < 0.01). CONCLUSION: After AGMI, the numbers of MCs and the degranulated MCs, and the SP expression level in BL 20/BL 21 area were increased significantly, suggesting an involvement of MCs and SP in the process of AGMI-induced activation of acupoints.

Flunarizine pretreatment attenuates hyperthermia-induced extravasation in rats.

Previous work has established that there is an increase in endothelial permeability in hyperthermic rats. This work assessed the potential of the calcium channel blocker (E)-1-bis(4-fluorophenyl)methyl-4-(3-phenyl-2-propenyl)piperazine dihydrochloride (flunarizine) as a pretreatment to ameliorate this extravasation. Five groups of male rats (n=12 rats per group, 400-500 g) were given 0, 0.3, 1, 2, or 3 mg/kg flunarizine (FL0, FL0.3, FL1, FL2, and FL3, respectively) by gavage 30 min prior to induction of hyperthermia. Hyperthermia was achieved by placing unrestrained animals in their own cages in a chamber maintained at 41.5 degrees C until a core temperature (Tc) of 42.6 degrees C was attained. Then, 25 mg/kg of Evans blue in saline was administered via a jugular cannula. After 15 min the animals were anesthetized, exsanguinated, tissues removed and washed in saline, and Evans blue extracted with formamide. As the dose of flunarizine was increased, there was a significant (P<0.05) reduction of Evans blue recovered from the liver, kidney, lung, spleen, and intestinal tissue. Endurance time in the heat to reach a Tc of 42.6 degrees C increased significantly from 194+/-39 min (mean+/-SD) with FL0 to 275+/-33 min with FL1, but decreased again with FL2 (206+/-42) and FL3 (199+/-60). Thus, flunarizine pretreatment attenuated hyperthermia-induced extravasation, and 1 mg/kg flunarizine markedly increased the tolerance time to heat exposure.