Effect of subdiaphragmatic vagotomy and cholinergic agents in the hypothalamic-pituitary-adrenal axis activity.

In the present study, we examined whether the vagus nerve is involved in mediating the stimulation of hypothalamic-pituitary-adrenal (HPA) axis by cholinergic muscarinic and nicotinic agonists, carbachol and nicotine. The site of HPA axis muscarinic stimulation was determined using peripheral (i.p.) and intracerebroventricular (i.c.v.) administration of carbachol, atropine sulphate (AtrS) and atropine hydrobromide (AtrBr). The i.p. carbachol-(0.5 mg/kg)-induced corticosterone response was significantly reduced by i.p. pretreatment with AtrBr (0.1 mg/kg), but was not diminished by i.c.v. AtrS (0.1 mug). The increase in corticosterone secretion induced by i.c.v. carbachol (2 microg) was totally abolished by i.c.v. pretreatment with AtrS (0.1 microg) but was not altered by i.p. AtrBr. Subdiaphragmatic vagotomy performed 2 weeks earlier substantially decreased the i.p. carbachol (0.2 mg/kg)-induced ACTH response and markedly augmented ACTH and corticosterone response to a higher dose of carbachol (0.5 mg/kg) in comparison with the responses in sham operated rats. Vagotomy abolished the stimulatory effect of i.p. nicotine in a low dose (1 mg/kg) on ACTH and corticosterone secretion; the ACTH response to higher dose (2.5 mg/kg) was considerably reduced, while corticosterone response remained unaffected. These results suggest that carbachol given i.c.v. evokes considerable corticosterone response by stimulation of central cholinergic muscarinic receptors. A major part of the i.p. carbachol-induced corticosterone secretion results from peripheral cholinergic muscarinic receptor stimulation. Subdiaphragmatic vagotomy moderately intensified the carbachol-induced ACTH and corticosterone secretion. Vagotomy significantly reduced the nicotine-induced ACTH secretion, possibly by the involvement of vagal afferents. The nicotine-induced corticosterone secretion is not exclusively regulated by circulating ACTH but by various intra-adrenal regulatory components.     

Morphofunctional state of the cholinergic innervation of the rat pancreas during vagotomy]

Cholinergic innervation of the albino rat pancreas was investigated under normal conditions and after bilateral subdiaphragmatic vagotomy (one, three, seven, twenty one days and two months after the operation). In control animals cholinergic nerve fibers were found in all the organ structures -- both in the vascular and in the gland-duct systems. Vagotomy resulted in a short-term increase in the nerve fibers revealed at the end of the first day, followed by their decrease on the seventh day; but in two months the number of detectable nerve fibers approached the initial level.     

Morphometric analysis of the state of the intramural nervous apparatus of rat duodenum]

Structural organization of the intramural apparatus of the duodenum has been studied in normal white rats. By means of a planimeter, the area of the nerve cells and their nuclei has been estimated in serial sections of the cranial and caudal parts of the duodenum; a definite regularity on the nerve cell types distribution has been stated in different parts of the duodenum. Concentration of afferent nerve elements has been noted in the cranial part of the duodenum.     

Morphologic and histochemical indices of hepatic function following bilateral subdiaphragmatic vagotomy

A complex morpho-functional investigation of the rat liver was performed after bilateral subdiaphragmal vagotomy by means of light, electron microscopy methods and a quantitative histochemical method. Some ultrastructural disorders in hepatocytes and in stellate reticuloendotheliocytes were revealed, with their maximal manifestation 7 days after vagotomy. At later stages (45 and 90 days), compensatory-restorative processes develop resulting in considerable (but not complete) normalization of the organ's structure. Quantitative histochemical investigations have demonstrated that even at the highest degree of the resulted disorders the liver preserves its ability to synthesize and accumulate glycogen, but the intensity of the process is considerably lowered. Functional changes are reversible in their character and correlate to the degree of structural disorders.     

Morphofunctional characteristics of the duodenum in the early stages of experimental escherichiosis

Using the model of experimental colibacillosis in mice morphological, immunomorphological and morphometrical studies of duodenum 1 to 24 hours after inoculation were performed. Typical dynamics of cellular composition in the intestinal wall, accompanied with increased lymphoplasmacellular infiltration, and dystrophic changes in cells of submucosal and intermuscular neuroplexuses were found. The data obtained testify, that the infectious process at the acute state of experimental colibacillosis has an immune character (immediate hypersensitivity of local type), characterised by increasing in immunoglobulin-containing cells and including in this process of mast and endocrine cells.     

Physiologic regeneration of jejunal epithelium following bilateral subdiaphragmatic vagotomy in rats]

Seven days after vagotomy in rats there was an increase of the mitotic activity of the epithelium of the small intestine; this index was about 1.5 greater in the experimental ats in comparison with control animals. Daily rhythm of the mitotic activity was constant under these conditions, but the amplitude of daily fluctuations was levelled. Vagotomy failed to alter the stable regimen of renovation of the cell population of the "crypt-villus" system.     

Changes in the intramural neural apparatus of the stomach and gallbladder in the late periods after vagotomy

By means of morphological methods changes in the wall of the stomach central part and in that of the bile bladder have been studied in 15 patients after a remote vagotomy (in 7-17 years). Material of biopsies and resections has been investigated. In the wall of the organs in question focal and diffuse mono- and plasmocytic infiltrates, leucocytic invasion of the mucous membrane epithelium, microerosions, microfocal hemorrhages in the external layers of the muscular sheath have been revealed. Inflammatory-degenerative and dystrophic changes are observed in the intramural ganglia, in large and small fasciculi of the muscular-intestinal nervous plexuses. In the tissues of the organs studied there are no myelin fibers, that are ++pre-ganglial and receptor conductors. The degeneration of these fibers after vagotomy and loss of connections in the organs investigated with the CNS are supposed to result in essential changes not only of the nervous trophic of tissues in all membranes and sheaths, but bring about changes in the intramural nervous apparatus itself. These changes, in their turn, cause imbalance + in the neurogumoral regulation and can be considered as the base of a number of postvagotomic structural-functional disturbances.     

Gastric emptying in response to IAPP and CCK in rats with subdiaphragmatic afferent vagotomy

In the subdiaphragmatic vagal deafferentation procedure (SDA), the afferent fibers of the vagus are surgically severed unilaterally where they enter the brain stem. The technique includes a subdiaphragmal truncal vagotomy performed on the contralateral side. This procedure has been used to study the control of food intake, but it has not been used previously to investigate the role of vagal afferent fibers in the control of gastric emptying (GE). The current experiment studied the effect of SDA on the inhibition of GE by islet amyloid polypeptide (IAPP or amylin) and cholecystokinin (CCK) in awake, unrestrained rats with gastric cannulas. The experimental group underwent subdiaphragmatic vagal deafferentation; the control group had sham operations. All rats received 20-min intravenous infusions of IAPP (1, 3, 9, 27, and 81 pmol/kg/min), CCK (3, 30 and 90 pmol/kg/min), and normal saline in random order. Gastric emptying of saline was measured by the phenol red method during the last 5 min of each infusion period. CCK dose-dependently inhibited gastric emptying in both the control and SDA animals. The inhibition of GE by CCK was significantly attenuated by SDA (p<0.01). IAPP also inhibited gastric emptying dose-dependently, but the difference between the SDA and control groups was not significant. The current experiment, which used a different methodology than previous studies, provides support for the hypothesis that the inhibition of gastric emptying by CCK, but not by IAPP, is mediated partly by afferent vagal fibers.     

Morphofunctional analysis and trophic adaptations: the case of bill apparatus of Old World flycatchers

A morphofunctional analysis of the bill apparatus was conducted on some African forest flycatchers (Muscicapidae, Platysteiridae, Monarchidae) in relation to detailed eco-ethological data available on these species. The aim was to evaluate relationships between anatomical structures and habitat constraints and also identify the most pertinent trophic adaptations. If forest Muscicapidae have essentially conserved the generalized passerine structures and occupy open-habitat niches in the forest, Platysteiridae and Monarchidae have adapted to forest conditions and show a key-adaptation based on specific changes in the structure of the bill apparatus in response to particular light patterns and habitat clogginess, constraints that require speed and precision for the capture of prey and protection of the skull against collisions.     

Morphological research on the effect of vagotomy on the parietal microflora of the stomach and duodenum

The effect of vagotomy on parietal microflora was studied in intact rats and rats with chronic experimental gastric ulcer using stereometry, as well as light, transmission and scanning electron microscopy. Vagotomy was found to increase the relative amount of parietal microflora on day 30 following denervation, especially in the duodenum and pylorus. Chronic gastric ulcers are also associated with a rise in the relative amount of parietal microflora.     

Morphofunctional changes in the insular apparatus of the pancreas following hypophysectomy and administration of somatotropic hormone]

Mature white male rats were used to study effects of hypophysectomy and STH on sugar content after fasting and after reiterated glucose loading. Morphological and morphometrical investigation of the pancreatic endocrine tissue were made. Zinc content and distribution in the pancreas, as well as aldehydefuchsinophil granulation in B-cells of the islets of Langergans were studied. Hypophysectomy was stated to increase functional activity of the pancreatic insular apparatus. Injection of STH for 9 days resulted in the stimulation of the cells in the insular apparatus. Prolonged injection of STH (for 20 days) produced exhaustion of the pancreatic insular apparatus.     

Morphofunctional restructuring of the nervous system of the lymphoid organs during electrostimulation of the hypothalamus

The intramural nervous apparatus of rabbit lymphoid organs was examined after 15 and 30 sessions of electric stimulation of the posterior hypothalamus. The function of nerve cells was evaluated by cytophotometry according to the content of catecholamines and acetylcholinesterase (ACE) activity. In the mesenteric lymph nodes, stimulation led to a decrease in the activity of both adrenergic and ACE-containing nerve cells. The spleen demonstrated a reduction in the catecholamine content in the perivascular nerve plexuses, with a simultaneous rise of the catecholamine content in the fibers located in the parenchyma, which evidences inhibition of the neurogenous mechanisms of vasomotor control and possible selective activation of the sympathetic mechanisms involved in the regulation of the immunogenesis. Thymic preparations impregnated with silver salts manifested high argyrophilia of the nerve cells, characteristic of the reactive phase of the destructive process. The problems of the hypothalamic effects on the blood supply and functions of the immune system organs are discussed.     

Changes in the mucosa of the duodenum and stomach as a result of experimental duodenal ulcers and vagotomy

By means of the transmissive and scanning electron microscopy methods and radioautography, structure of mucous membrane of the stomach and duodenum has been studied under experimentally induced duodenal ulcers before and after vagotomy during various time. The vagotomy results in accelerated healing of the ulcer defect. This is connected with an increased proliferative activity in the crypta cells, however, this is accompanied with deceleration of their differentiation. Under the duodenal ulcers the amount of chief and parietal cells increases in the gastric mucous membrane, this depends on gastrostasis produced by stenosis of the pylorus. At vagotomy the amount of the chief and parietal cells in the fundal glands of the mucous membrane decreases; this is accompanied with a lowered secretory activity.