[Involvement of sympathetic nerve activation in acupoint application induced improvement of gastric ulcer and motility in rats with gastric ulcer]

OBJECTIVE

To observe the effect of mustard oil application at "Liangmen" (ST21) on gastric ulcer (GU) and gastric motility and its association with the sympathetic nerve activity in rats with GU, so as to provide experimental basis for improvement of GU by acupoint application.

METHODS

Thirty-nine male SD rats were randomly divided into control (n=7), model, acupoint application (AA), medication (guanethidine, an adrenergic sympathetic antagonist) and AA+medication groups (n=8 in each of the latter 4 groups). The GU model was made by applying acetic acid-immersed filter paper onto the gastric antrum. For rats of the AA and AA+medication groups, 50% mustard oil was applied to left ST21 for 10 min, once a day, for 9 consecutive days. Rats of the medication and AA+medication groups received intraperitoneal injection of guanethidine solution (40 mg/kg) beginning from the modeling day on, once a day for 10 consecutive days. The rat's body weight of each group was recorded on the 0th, 1st, 3rd, 7th and 9th day. The intragastric peristaltic wave frequency and the myoelectrical activity (frequency of slow waves, and integration of fast waves) of the gastric smooth muscle were recorded by using PowerLab data acquisition system. The gastric ulcer area was measured after the rats were executed, and histopathological changes of gastric antrum tissues (histopathological score including epithelial cell injury, submucosal edema, hemorrhagic injury, inflammatory cell infiltration score) were observed after H.E. staining.

RESULTS

Compared with the control group, the body weight ratio, frequency of gastric peristaltic waves and slow wave frequency of gastric smooth muscle were significantly decreased (P<0.001, P<0.05), while the ulcer area, total histopathological score, epithelial cell injury score, submucosal edema score, hemorrhagic injury score and inflammatory cell infiltration score were significantly increased in the model group (P<0.05, P<0.001). Relevant to the model group, the AA group had a significant increase in the body weight ratio, frequency of gastric peristaltic waves, slow wave frequency, integration of fast waves (P<0.05, P<0.001), and a considerable decrease in the ulcer area, total histopathological score, epithelial cell injury score, submucosal edema score, hemorrhagic injury score and inflammatory cell infiltration score (P<0.05, P<0.001), and the medication group has a significantly decrease in the frequency of gastric peristaltic waves (P<0.05). In comparison with the AA group, the body weight ratio, frequency of gastric peristaltic waves and slow wave frequency of gastric smooth muscle in both medication and AA+medication groups, and the integration of fast waves in the medication group were obviously lower (P<0.05, P<0.001, P<0.01), whereas the levels of ulcer area, total pathological score, submucosal edema score, hemorrhagic injury score and inflammatory cell infiltration score in both medication and AA+medication groups, and the epithelial cell injury score in medication group were significantly higher (P<0.05, P<0.001).

CONCLUSION

Application of mustard oil at acupoint ST21 can effectively remit GU caused by acetic acid and regulate gastric rhythmic contraction, which was mediated by sympathetic nerve.

Bone mass loss in chronic heart failure is associated with sympathetic nerve activation

PURPOSE

Chronic heart failure causes osteoporosis, but the mechanism remains unclear. The sympathetic nerve plays an important role in both bone metabolism and cardiovascular function.

METHODS

Thirty-six adult male SD rats were randomly divided into the following four groups: sham surgery (Sham) group, guanethidine (GD) group, abdominal transverse aorta coarctation-induced heart failure + normal saline (TAC) group, and TAC + guanethidine (TAC + GD) group. Normal saline (0.9 % NaCl) or guanethidine (40 mg/kg/ml) was intraperitoneally injected daily for 5 weeks. Then, DXA, micro-CT, ELISA and RT-PCR analyses were performed 12 weeks after treatment.

RESULTS

The bone loss in rats subjected to TAC-induced chronic heart failure and chemical sympathectomy with guanethidine was increased. Serum norepinephrine levels were increased in rats with TAC-induced heart failure but were decreased in TAC-induced heart failure rats treated with guanethidine. The expression of α2A adrenergic receptor, α2C adrenergic receptor, osteoprotegerin (OPG), and osteocalcin in the tibia decreased in the TAC-induced heart failure group, and the expression of β1 adrenergic receptor, β2 adrenergic receptor, receptor activator of nuclear factor-κ B ligand (RANKL), and RANKL/OPG in the tibia increased in the heart failure group. In addition, these changes in gene expression levels were rescued by chemical sympathectomy with guanethidine.

CONCLUSIONS

TAC-induced chronic heart failure is associated with bone mass loss, and the sympathetic nerve plays a significant role in heart failure-related bone mass loss.

MINI ABSTRACT

The present study supports the hypothesis that heart failure is related to bone loss, and the excessive activation of sympathetic nerves participates in this pathophysiological process. The present study suggests a potential pathological mechanism of osteoporosis associated with heart failure and new perspectives for developing strategies for heart failure-related bone loss.

[Sensory and sympathetic nerves are involved in the changes of skin temperature, blood infusion and inflammatory cytokines of cutaneous tissue in the sensitized area of colitis rats]

OBJECTIVE

To investigate the changes of skin temperature, blood infusion and inflammatory cytokines of cutaneous tissue in the sensitized area of colitis model rats, as well as the relationship between sensory and sympathetic nerves and the formation of sensitized area, and to initially reveal the partial physical-chemical characteristics of the sensitized area in the colitis model rats.

METHODS

Thirty-five male SD rats were randomly divided into a control group (n=10), a model group (n=18) and a guanethidine group (n=7). 5% dextran sulfate sodium (DSS) was adopted for 6-day free drinking to establish colitis model in the model group and the guanethidine group. On day 6 and 7, in the guanethidine group, guanethidine solution (30 mg/kg) was injected intraperitoneally for sympathetic block. On day 7, after injection of evans blue (EB) solution, the EB extravasation areas on the body surface were observed to investigate the distribution and physical-chemical characteristics of the sensitized area. The control area was set up, 0.5 cm away from the sensitized area, and with the same nerve segment innervation. Disease activity index (DAI) score of rats was compared between the normal group and the model group, and the morphological changes in the colon tissue were investigated with HE method. Using infrared thermal imaging technology and laser speckle flow imaging technology, skin temperature and blood infusion were determined in the sensitized area and the control area of the rats in the model group. Immunofluorescence technique was adopted to observe the expression levels of the positive nerve fibers of substance P (SP), calcitonin gene-related peptide (CGRP) and tyrosine hydroxylase (TH), and the correlation with blood vessels; as well as the expression levels of SP positive nerve fibers/tryptase⁺ mast cells, and tryptase⁺ mast cells/5-hydroxytryptamine (5-HT) in skin tissue in the sensitized area and the control area of the rats in the model group. MSD multi-level factorial method and ELISA were applied to determine the contents of pro-inflammatory and anti-inflammatory cytokines (e.g. TNF-α, IL-1β, IL-6, IL-4 and IL-10) and anti-inflammatory substance corticosterone (CORT).

RESULTS

Sensitization occurred at the T₁₂-S₁ segments of the colitis model rats, especially at L₂-L₅ segments. Compared with the normal group, DAI score was increased in the rats of the model group (P<0.05), and the colonic mucosal damage was obvious, with the epithelial cells disordered, even disappeared, crypt destructed, submucosal edema and a large number of inflammatory cells infiltrated. In comparison with the control area, the skin temperature and blood infusion were increased in the sensitized area of the model group (P<0.05, P<0.01); as well as the expression levels of the positive nerve fibers of SP, CGRP and TH of skin tissue (P<0.05), which was specially distributed in peripheral vessels, the expression levels of SP positive nerve fibers/tryptase⁺ mast cells, and tryptase⁺ mast cells/5-HT of the skin tissue were all expanded (P<0.05) in the sensitized area of the model group. Compared with the model group, the number of sensitized areas was reduced in the guanethidine group (P<0.05). In comparison with the control area of the model group, in the sensitized area, the contents of pro-inflammatory cytokines, e.g. TNF-α, IL-1β and IL-6, and the anti-inflammatory substance CORT of skin tissue were all increased (P<0.05); and the contents of IL-6 and TNF-α were negatively correlated with CORT (P<0.05).

CONCLUSION

The sensitized areas on the body surface of colitis rats are mainly distributed in the L₂-L₅ segments. Sensory and sympathetic nerves are involved in the acupoint sensitization, and the sensitized areas may have the dynamic changes in pro-inflammatory and anti-inflammatory substances.

The response to transmural stimulation of isolated arterial strips and its modification by drugs

Transmural electrical stimulation of isolated aortic strips of rabbits, induced contractions of the muscle which were blocked by concentrations of cocaine and lignocaine which augmented the response to noradrenaline. The adrenergic neurone blocking agents bretylium, guanethidine and bethanidine also blocked selectively the response to transmural stimulation. With bretylium and guanethidine the responses to noradrenaline were augmented. α-Receptor blockade with piperoxan, phentolamine, phenoxybenzamine and dihydrogenated ergot alkaloids also blocked the responses to transmural stimulation. Cocaine in low concentration and dexamphetamine augmented the responses to electrical stimulation. They also delayed onset of block with adrenergic neurone blocking drugs and reversed this when it was already established. Hexamethonium and pentolinium, in concentrations which in other tissues are known to cause complete blockade of ganglionic transmission. had no effect on electrical stimulation. It is concluded that the responses to electrical stimulation are the result of excitation of post-ganglionic adrenergic axons in the walls of the arterial preparation. Strips of common carotid, superior mesenteric, renal, pulmonary and common iliac arteries of the rabbit gave responses to electrical stimulation similar to those of the aorta.

Antagonism of Guanethidine by Dexamphetamine and Other Related Sympathomimetic Amines

Dexamphetamine and certain other indirectly acting sympathomimetic amines prevent or reverse the sympathetic nerve blocking action of guanethidine in anaesthetised cats and dogs. Noradrenaline and dopamine do not antagonise the blocking action of guanethidine. These observations are discussed in relation to the mode of action of guanethidine and to a possible clinical significance of these findings.

The Effect of Some Anti-Acetylcholine Drugs on the Responses of the Isolated Rabbit Intestine to Sympathetic Nerve Stimulation and To the Action of Adrenergic Neurone Blocking Agents

The effects of atropine and some quaternary derivatives on the inhibitory responses of the Finkleman preparation to stimulation of the periarterial sympathetic nerves and to added adrenaline were examined. None of the compounds tested appeared to affect the inhibitory responses with the exception of N-diphenylmethylatropine, which much enhanced the inhibitory effect of the electrical stimulation. In addition, this compound antagonised in vitro, but not in vivo, the activity of several adrenergic neurone blocking compounds, but not guanethidine.

Spectrophotometric method for the estimation of guanethidine

A spectrophotometric method for the estimation of guanethidine sulphate, based on the development of blue colour in alkaline medium after reaction with lithium and sodium molybdophosphotungstate B.P. reagent, is described. The method is more sensitive and rapid than the existing British Pharmacopoeia methods. Both powder and tablets can be estimated by this method.

The effects of blocking agents upon the isolated vas deferens of the guinea-pig stimulated by the hypogastric nerve

When the guinea-pig isolated vas deferens preparation was stimulated by its hypogastric nerve, the responses obtained at different frequencies of stimulation were all reduced proportionately by guanethidine, bretylium, reserpine and pentamethonium. The difference between guanethidine and bretylium in affecting the responses to nervous stimulation at different frequencies of the cat nictitating membrane reported by Boura & Green was not observed with this preparation. Papaverine reduced responses to high frequencies of stimulation more than those to low frequencies. Amphetamine also reduced responses to all frequencies uniformly except in the smallest doses used, which potentiated the responses to high frequencies; these doses reversed the reduction in response by guanethidine, bretylium and reserpine. Preparations stimulated between parallel electrodes responded similarly to those stimulated by the hypogastric nerve.