Reserpine, vagal adrenergic activity and stress-induced acute gastric mucosal injury in the rat

Ventromedial hypothalamic nucleus in regulation of stress-induced gastric mucosal injury in rats

Previous studies showed that restraint water-immersion stress (RWIS) increases the expression of Fos protein in the ventromedial hypothalamic nucleus (VMH), indicating the VMH involving in the stress-induced gastric mucosal injury (SGMI). The present study was designed to investigate its possible neuro-regulatory mechanisms in rats receiving either VMH lesions or sham surgery. The model for SGMI was developed by restraint and water (21 ± 1 °C) immersion for 2 h. Gastric mucosal injury index, gastric motility, gastric acid secretion and Fos expression in the hypothalamus and brainstem were examined on the 15th postoperative day in RWIS rats. Gastric mucosal injury in VMH-lesioned rats was obviously aggravated compared to the control. Gastric acidity under RWIS was obviously higher in VMH-lesioned rats than that in sham rats. Meantime, the VMH-lesioned rats exhibited marked increases in the amplitude of gastric motility in the VMH lesions group after RWIS. In VMH-lesioned rats, Fos expression significantly increased in the dorsal motor nucleus of the vagus (DMV), the nucleus of the solitary tract (NTS), the area postrema (AP), the paraventricular nucleus (PVN) and the supraoptic nucleus (SON) in response to RWIS. These results indicate that VMH lesions can aggravate the stress-induced gastric mucosal injury through the VMH-dorsal vagal complex (DVC)-vagal nerve pathway.

Effects on neuroendocrinoimmune network of Lizhong Pill in the reserpine induced rats with spleen deficiency in traditional Chinese medicine

AIM OF THE STUDY

Lizhong Pill, composed of radix Ginseng (Panax ginseng C.A. Meyer), rhizoma Zingiberis (Zingiber officinale Roscoe), rhizoma Atractylodis Macrocephalae (Atractylodes macrocephala Koidz.) and radix Glycytthizae (Glycyrrhiza uralensis Fisch.), is a classical herbal product for curing spleen deficiency in traditional Chinese medicine (TCM), and reserpine treated rats show similar signs to TCM spleen deficiency pattern. This paper is aimed to explore the regulatory effect on neuroendocrinoimmune network by Lizhong Pill in reserpine induced TCM spleen deficiency rats.

MATERIALS AND METHODS

100 healthy adult male SD rats, with a mean weight of 200 g, were randomly divided into five groups in average: control group, reserpine treated group, atropine treated group, treatment groups with Lizhong Pill at high dose and low dose (equal to the dosage of crude drugs for 4 g/kg/d and 8 g/kg/d). Rats in reserpine treated group were induced by intraperitoneal injection of reserpine at 0.5 mg/kgd for 4 weeks. The levels of IL-1, IL-6 and gastrin were measured with radioimmunoassay, TNF-α and IFN-γ in serum were measured with ELISA, the level of vasoactive intestinal peptide (VIP) and substance P (SP) in small intestine were determined with radioimmunoassay, and the TNF-α and TGF-β positive cells in small intestine were detected by immunohistological staining. Data were analyzed with SAS 9.1 software package.

RESULTS

The rats in reserpine treated group, body weight, concentrations of IFN-γ, IL-1 and TNF-α in serum, expression of TGF-β in small intestine, VIP in small intestine decreased (P<0.05), and the level of IL-6 in serum, expression of TNF-α, SP in small intestine and gastrin were increased (P<0.05). Administration of Lizhong Pill at high dose could increase the body weights at day 21, and the weights of rats in Lizhong Pill groups were much higher compared to reserpine treated group. At high dose of Lizhong Pill could increase the level of TNF-α in serum. Lizhong Pill at high dose and low dose could reverse the changes of IL-1, IL-6 and IFN-γ, gastrin, expression of TGF-β and TNF-α, VIP and SP in small intestine.

CONCLUSIONS

The rats treated with reserpine, with similar signs to TCM spleen deficiency, show neuroendocrinoimmune disorders, and the restoration of the neuroendocrinoimmune disorders might be the part of mechanism of Lizhong Pill for reinforcing TCM spleen deficiency.

Effects of near-infrared low-level laser irradiation on microcirculation

BACKGROUND AND OBJECTIVE

Recently, there has been an increase in the clinical application of low-level laser irradiation (LLLI) in various fields. The present study was conducted to explore the effects of LLLI on microcirculation.

STUDY DESIGN/MATERIAL AND METHODS

We investigated the effects of LLLI on rat mesenteric microcirculation in vivo, and on cytosolic calcium concentration ([Ca2+]i) in rat vascular smooth muscle cells (VSMCs) in vitro.

RESULTS

LLLI caused potent dilation in the laser-irradiated arteriole, which led to marked increases in the arteriolar blood flow. The changes were partly attenuated in the initial phase by the superfusion of 15 microM L-NAME, but they were not affected by local denervation. Furthermore, LLLI caused a power-dependent decrease in [Ca2+]i in VSMCs.

CONCLUSION

The circulatory changes observed seemed to be mediated largely by LLLI-induced reduction of [Ca2+]i in VSMCs, in addition to the involvement of NO in the initial phase.

Effect of psychogenic stress on gastrointestinal function

This review summarizes the studies published over the last twenty years on the effects of psychogenic stress on gastrointestinal function, using animal models. The effects of stress on gastric ulceration have received wide attention and the central and local mechanisms of mucosal damage have been, for the most part, clearly delineated. In comparison, relatively few studies have focused on the impact of stress on intestinal and colonic physiology, even though its influence on intestinal motility, mucosal permeability and inflammation has been established. More work is necessary in this field, especially considering the importance of irritable bowel syndrome in modern society.

Brain ischemia and gastric mucosal damage in spontaneously hypertensive rats: the role of arterial vagal adrenoceptors

Brain ischemia is often accompanied by acute gastric lesions. To clarify the underlying mechanism, the influence of acute ischemic insult to the brain on gastric hemodynamics and mucosal integrity was examined in spontaneously hypertensive rats. One hour after brain ischemia, gastric mucosal blood flow decreased to 71% of the preischemic levels in the control rats but was preserved significantly better, at 94 and 108%, in the prazosin-treated and guanethidine-treated rats, respectively. Vagotomy almost abolished the decrease in gastric mucosal blood flow during cerebral ischemia. Intragastric 0.6 N hydrochloric acid administered just after reperfusion induced more severe hemorrhagic ulcers in the control than in the prazosin-treated and vagotomized groups. These results suggest that noradrenergic neurons acting through alpha1-adrenoceptors contributes to the decrease in gastric mucosal blood flow, and the subsequent disturbed integrity of the gastric mucosa, through the vagal adrenergic pathway during brain ischemia in spontaneously hypertensive rats.

Gastric mucosal cytoprotection in the rat by scavenging oxygen-derived free radicals

Oxygen-derived free radicals are cytotoxic and promote tissue damage. Dimethyl sulfoxide (DMSO) and allopurinol scavenge hydroxyl radicals, and the latter agent also inhibits the enzyme xanthine oxidase, which is responsible for the formation of superoxide anions. These agents were given daily by gavage (1 ml/d). After 2 days of administration as 1, 2, or 5% solutions, the H+ output of the rat with or without pyloric ligation was not significantly affected. After six hours reserpine (5 mg/kg i.p.) or serotonin (50 mg/kg i.p.) produced ischemic mucosal injury in all stomachs (39 +/- 5.2 mm2 and 25.9 +/- 2.8 mm2, mean +/- standard error of the mean [SEM], n = 10). Pretreatment for 2 days with 1 ml/d of 1% allopurinol or DMSO significantly (p less than 0.001) protected the rat against the reserpine (23 +/- 2.1 mm2 and 24 +/- 1.9 mm2, respectively, vs 39 +/- 5.2 mm2, n = 10) and serotonin injury (10 +/- 1.5 mm2 and 11 +/- 1.8 mm2, respectively, vs 25.9 +/- 2.8 mm2, n = 10). However, 2 days pretreatment with 1 ml/d of 2% allopurinol or DMSO was more effective (p less than 0.001) in this respect, and injury only developed in 40% of the rats given reserpine (8 +/- 1.2 mm2 and 9 +/- 1.6 mm2) and in 20% of those given serotonin (2.4 +/- 0.4 mm2 and 1.9 +/- 0.5 mm2). Similar pretreatment with 5% solutions completely protected the rat stomach against the reserpine and serotonin injuries without significantly influencing the H+ output.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential effects of reserpine on brainstem catecholaminergic neurons revealed by Fos protein immunohistochemistry

The effects of a single systemic injection of reserpine on c-fos proto-oncogene expression in catecholaminergic neurons of the rat brainstem were studied by immunohistochemistry for Fos proteins (Fos). In control rats, a few Fos immunoreactive neuronal nuclei were observed in the tectum and mesencephalic central gray. Within hours after drug injection, a substantial number of brainstem neurons stained intensely for Fos. The staining was maximal at 6 h and returned to control levels within 24 h. Double-immunohistochemical staining with antibodies to tyrosine hydroxylase revealed that in all noradrenergic (NA) neuron subgroups except the A2 group, the majority of NA neurons stained for Fos. Most adrenergic neurons were also labeled. In contrast, aside from some cells in the ventral tegmental area, reserpine did not induce Fos immunoreactivity in dopaminergic neurons. Numerous non-catecholaminergic neurons were intensely stained with Fos in the substantia nigra pars reticulata, ventral tegmental area, mesencephalic central gray, pontine nuclei and tectum. A small number of Fos immunoreactive neurons was also observed in raphe nuclei. Injection of saline (i.p.) resulted in a moderate increase in Fos immunoreactivity in the locus ceruleus, in A1/C1 neurons and in the mesencephalic central gray. The results demonstrate that acute reserpine treatment induces Fos expression in distinct populations of brainstem neurons, comprising both catecholaminergic and non-catecholaminergic neurons. Thus, induction of Fos by reserpine does not coincide with the site of action of this drug. The distribution of Fos immunoreactive NA neurons after reserpine treatment is comparable to that reported after application of stressful stimuli.(ABSTRACT TRUNCATED AT 250 WORDS)

Protection against stress-induced acute gastric mucosal injury by free radical scavengers

This study investigated whether the free radical scavengers allopurinol (50 mg p.o. q.i.d.) and dimethyl sulphoxide (DMSO, 500 mg p.o. q.i.d.) influence the incidence of stress-induced acute gastric mucosal injury in patients with pelvic fractures and hypovolaemic shock. In 177 fully evaluable patients (control n = 58, allopurinol n = 62, DMSO n = 57), endoscopically proven stress-induced injury evolved in a significantly (p less than 0.01) larger number of controls relative to either group on active therapy. During the first 3 days after hospitalization, 13 controls (22%) developed the injury whereas only 2 patients in each of the allopurinol (3%) and DMSO (4%) groups had this injury. Of these cases, 8 controls (14%) and one patient in the allopurinol group (2%) deteriorated and underwent emergency surgery, however 3 of the controls (5%) died in the immediate post-operative period. The results suggest that oxygen-derived free radicals are directly implicated in stress-induced acute gastric mucosal injury and that removing them protects against this injury and its complications.

Administration of sulfhydryls to stimulate the healing of ischemia-induced acute gastric mucosal injury in the rat

The sulfhydryl-containing agents DL-cysteine and DL-methionine-methyl sulfonium chloride (1-5%), administered orally by gavage for 4 days, stimulate the healing of acute ischemic injury of the rat gastric mucosa produced by 5 mg/kg of reserpine or 50 mg/kg of serotonin (5-hydroxytryptamine) injected once ip without influencing acid secretion (i.e., by cytoprotective mechanisms).

Gastric mucosal cytoprotection in the rat by naftidrofuryl oxalate

Ischaemic gastric mucosal injury was assessed in the rat by measurement of the area of the injury produced after 6 h by reserpine (5 mg kg-1 i.p.) or 5-hydroxytryptamine (5-HT) (50 mg kg-1 i.p.). Pretreatment with naftidrofuryl 1 mL, 1% by gavage significantly (P less than 0.001) protected the rat stomach against the reserpine (24 +/- 2.7 mm2 vs 40 +/- 4.7 mm2, mean +/- s.e.m., n = 10) and 5-HT injury (11.4 +/- 1.7 mm2 vs 27 +/- 4.1 mm2, mean +/- s.e.m., n = 10). Naftidrofuryl 1 mL 2% by gavage was more effective (P less than 0.001) in this respect and mucosal injury only developed in 50% of rats injected with reserpine (9.4 +/- 1.1 mm2) and 30% of those injected with 5-HT (3.2 +/- 0.4 mm2). Administration of naftidrofuryl 1 mL 5% by gavage completely protected the rat against both the reserpine- and 5-HT-induced acute gastric mucosal injury. This protection was not associated with any significant influence on the H+ output.

Protection by procaine hydrochloride against reserpine-induced acute gastric mucosal injury in the rat: implications for stress-induced injury

This study investigated whether oral procaine (1 mL of 5% solution) affords protection against reserpine-induced (5 mg/kg, ip) acute gastric mucosal injury in the rat. After 6 h, all rats in the reserpine-alone group developed mucosal injury confined to the glandular stomach (40.1 +/- 5.2 mm2, mean +/- SEM), and neither atropine (5 mg/kg, ip) or cimetidine (40 mg/kg ip) influenced this injury (38 +/- 4 and 40.5 +/- 4.6 mm2, respectively). Similarly, celiac ganglionectomy, to interrupt autonomic sympathetic delivery to the stomach, had no effect on the reserpine-induced injury (42 +/- 6 versus 40.1 +/- 5.2 mm2). Dose-dependent protection against the reserpine injury was produced by the alpha-adrenoceptor blocking drug phenoxybenzamine or phentolamine: a complete protection was noted with the 15-mg/kg dose. Vagotomy or procain completely protected the rat stomach against the reserpine injury. The data suggest that reserpine produces vagal adrenoceptor delivery to the rat stomach, resulting in mucosal injury, and that oral procaine blocks this delivery, thus achieving protection against injury development by a vagotomy action. The knowledge that the reserpine injury is a stress-induced injury indicates that oral procaine protects the rat stomach against stress-induced acute gastric mucosal injury.

The hypothalamus and gastric mucosal injuries: origin of stress-induced injury?

This paper reviews the role of the central nervous system in the genesis of gastrointestinal mucosal injuries. The discussion makes particular reference to the significance and mechanism of stress-induced injury of the gastroduodenal mucosa. It points out that in the rat, stress activates the hypothalamus, producing delivery of alpha-adrenergic stimulation to the stomach by the adrenergic hypothalamovagal pathway. This stimulation controls intragastric blood flow and 5-HT release. Low magnitude pharmacologically-induced stress enhances gastric acid secretion and, if this stress is maintained, it produces chronic duodenal ulceration. High magnitude pharmacologically-induced stress depresses acid secretion and injures the gastric mucosa. If such stress is maintained, it produces chronic gastric ulceration. The paper provides a detailed account of the mechanisms of these stress-induced gastroduodenal effects.