Changes in rat liver mitochondria after bilateral subdiaphragmatic vagotomy

Changes in the liver mitochondria of rats after bilateral subdiaphragmatic vagotomy were studied. Two stages were distinguished in the dynamics of the response of the mitochondrial system to denervation. During the first stage (0.5–3 days after vagotomy) reversible functional disturbances due to postoperative stress took place in the mitochondria. The second stage (7–60 days after denervation) is characterized by more marked structural and functional changes with some common features with those observed in hypoxia and resulting from vagotomy itself.Department of Histology, Therapeutic Faculty, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR S. S. Debov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 4, pp. 420–422, April, 1977.     

Acquisition of learned taste aversion following bilateral subdiaphragmatic vagotomy in rats

Bilateral subdiaphragmatic vagotomy in rats did not prevent subsequent acquisition of a conditioned taste aversion in a two-bottle preference paradigm. Neither verified-vagotomized nor sham-vagotomized animals shifted their preference when presentation of the preferred fluid was immediately followed by injection of isotonic NaCl, whereas both surgical groups shifted their preference to the initially-nonpreferred fluid when presentation of the initially-preferred fluid was followed by injection of isotonic LiCl. Although these results do not preclude some involvement of vagal innervation in toxiphobia conditioning in combination with other neural systems, they do indicate that the role of the vagus nerves is not a major one.     

Hyperphagia and obesity following ventromedial hypothalamic lesions in rats with subdiaphragmatic vagotomy

Bilateral subdiaphragmatic vagotomy chronically reduced body weight to 85–90% of sham vagotomy weight levels in female rats maintained on a standard pellet diet (observed for 114 days). Ventromedial hypothalamic lesions 70 days after vagotomy resulted in marked hyperphagia and obesity, although the increases were not as great as those following lesions in nonvagotomized animals. When the order of surgery was reversed, vagotomy reduced the body weight of obese VMH-lesioned rats to vagotomized control levels, with no evidence of recovery after 90 days. These results suggest that while enhanced vagal activity and/or vagally mediated hyperinsulinemia contribute to VMH lesion-induced overeating and weight gains, they are not necessary for the manifestation of either the hyperphagia or obesity. The importance of adaptation to the effects of vagal transections for the appearance of hypothalamic hyperphagia and obesity is discussed.     

Postabsorptive hyperinsulinemia in rats with subdiaphragmatic vagotomy

The effects of bilateral subdiaphragmatic vagotomy and of lateral hypothalamic lesions on the acute plasma glucose and insulin responses to liquid and solid meals were studied in female rats. Following recovery of an initial postoperative weight loss, vagotomized rats exhibited an exaggeration of plasma glucose and insulin responses compared to sham-vagotomized animals 17 min after the initiation of a liquid meal (6 ml sweetened milk in 7 min). Vagotomy did not alter basal glucose and insulin levels. The exaggerated postabsorptive response to oral liquid glucose in vagotomized rats was not observed after the consumption of an isocaloric solid meal (1.86 g sucrose pellets in 7 min). Rats with lateral hypothalamic lesions had significantly lower basal glucose and insulin levels, but both the preabsorptive and postabsorptive responses to oral glucose were unaffected by the lesion. The results in vagotomized animals were attributed to enhanced gastric emptying of liquid loads leading to a more rapid absorption of glucose from the intestine, which in turn resulted in an increased insulin response. In humans this is followed by rapid-onset hypoglycemia, and it is hypothesized that the abnormal postabsorptive glucose and insulin responses account in part for the pattern of small, frequent meals observed with vagotomized animals on liquid diets.     

Influence of anterior subdiaphragmatic vagotomy and TPN on rat feeding behavior.

Total parenteral nutrition (TPN) inhibits food intake and feeding behavior. Whether caloric sensory function of the liver contributes to this food intake and feeding behavior regulation via vagal-afferent innervation was tested after performing anterior hepatic vagotomy or sham operation in rats infused with a TPN solution providing 100% of daily energy needs, given continuously for 4 days. Food intake, meal number, size, duration, meal and intermeal sniffs, and eating activity were measured using an automated computerized rat eater meter (ACREM). TPN infusion resulted in a significant decrease of food intake and feeding indexes in both groups. The vagotomized rats showed a significantly higher food consumption, achieved by greater meal frequency, larger meal size, and longer meal duration. Thus, vagotomized rats consumed more than their controls by eating larger meals more often and of longer duration. Data suggest that anterior hepatic vagotomy interrupts hepatic caloric sensory feedback loop, diminishing inhibitory vagal effects on food intake with TPN, leading to an overall increase in food intake.     

Dietary self-selection in insulin-injected hamsters

Adult male golden hamsters were given access to a variety of nutrient sources and were observed following the administration of regular insulin. It was hypothesized that if insulin produced hyperphagia in hamsters by the activation of a glucoprivic feeding mechanism, a selective increase in carbohydrate consumption would be observed. All animals received subcutaneous injections of 10, 30, 50 and 100 units/kg of insulin as well as a control injection of saline. Food consumption was recorded at +3, +6 and +24 hours after injections. In Experiment 1 hamsters having continuous access to Purina lab chow, fat (Crisco) and sucrose (sugar cubes) increased their total caloric consumption in response to insulin, but did not do so by selectively increasing their carbohydrate intake. In Experiment 2 hamsters maintained on Purina chow and sugar cubes consistently increased their carbohydrate intake as well as their total caloric consumption in response to insulin, but again the increase in carbohydrate intake was not selective; increased consumption of both sugar cubes and Purina chow occurred, and neither the proportion of total calories derived from carbohydrate nor the proportion of total calories derived from sugar cubes was affected by insulin administration. The results support the conclusion that insulin-induced hyperphagia in hamsters results from the activation of a non-glucoprivic feeding mechanism.     

Morphological changes in the jejunal mucosa after bilateral subdiaphragmatic vagotomy

Bilateral subdiaphragmatic vagotomy in rats leads to development of a combination, of structural and ultrastructural changes in the jejunal mucosa and in its epithelial cells — enterocytes and goblet cells. In the early stages after the operation (1 and 7 days) morphological changes of destructive character predominate in the organ, whereas in the late stages (60 and 120 days) structural changes of a compensatory nature become increasingly predominant.Department of Histology and Embryology, Therapeutic Faculty, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR Yu. M. Lopukhin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 5, pp. 628–632, May, 1976.     

Dietary self-selection at cold temperatures

Animals housed in the cold (2°C) were given the opportunity to select the components of their diets from protein and carbohydrae fractions. Housing in the cold was accompanied by depressed growth, which was not affected by giving the animals the opportunity to select their diets. Animals in the cold increased total caloric intake relative to controls at room temperature (22°C). Selecting animals housed in the cold chose a lower percentage of the diet as protein (and, therefore, a higher percentage as carbohydrate) than did controls. Since protein intake levels did not differ as a function of environmental temperature, the altered dietary selection pattern was due to an increase in the absolute amount of carbohydrates consumed. These data were interpreted as suggesting that the level of protein selected is determined by age factors and the level of carbohydrate selected is determined by energy requirements.     

Changes in microglial activation within the hindbrain,nodose ganglia,and the spinal cord following subdiaphragmatic vagotomy

Damage to peripheral nerve branches triggers activation of microglia in CNS areas containing motor neuron soma and primary afferent terminals of the damaged fibers. Furthermore, microglial activation occurs in areas containing the soma and terminals of spared nerve branches of a damaged nerve. Because the abdominal viscera are innervated by spinal afferents as well as vagal afferents and efferents, we speculated that spinal nerves might respond like spared nerve branches following damage to vagal fibers. Therefore, we tested the hypothesis that damage to the abdominal vagus would result in microglial activation in vagal structures—the nucleus of the solitary tract (NTS), dorsal motor nucleus of the vagus nerve (DMV), and nodose ganglia (NG)—as well as spinal cord (SC) segments that innervate the abdominal viscera. To test this hypothesis, rats underwent subdiaphragmatic vagotomy or sham surgery and were treated with saline or the microglial inhibitor, minocycline. Microglial activation was determined by quantifying changes in the intensity of fluorescent staining with a primary antibody against ionizing calcium adapter binding molecule 1 (Iba1). We found that subdiaphragmatic vagotomy significantly activated microglia in the NTS, DMV, and NG two weeks post-vagotomy. Microglial activation remained significantly increased in the NG and DMV for at least 42 days. Surprisingly, vagotomy significantly decreased microglial activation in the SC. Minocycline treatment attenuated microglial activation in all studied areas. Our results indicate that microglial activation in vagal structures following abdominal vagal damage is accompanied by suppression of microglial activation in associated areas of the spinal cord.     

Morphological analysis of the adrenal cortex after bilateral subdiaphragmatic vagotomy

In Wistar rats 7 and 45 days after bilateral subdiaphragmatic vagotomy the zona fasciculata and zona reticularis of the adrenal cortex were enlarged and the content of unsaturated phospholipids in their cells was increased. In the medulla the venous sinusoids were greatly dilated. Administration of glucose to the vagotomized animals caused further accumulation of unsaturated phospholipids in the cells of the zona fasciculata but there was no change in the width of the zones. These facts indicate that after vagotomy precursors of steroid hormones accumulate; this is interpreted as a morphological sign of depression of functional activity of the zona fasciculata and zona reticularis of the adrenal cortex.Department of Histology and Embryology, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR Yu. M. Lopukhin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 9, pp. 1128–1130, September, 1976.     

Dietary self-selection in chronically insulin-treated golden hamsters

Adult male golden hamsters were maintained on either Purina Rat Chow (chow group) or a self-selection diet consisting of high-protein chow, pure carbohydrate, and pure fat (choice group). Animals were injected for 12 consecutive days with either long-acting insulin (20 U/kg for 4 days, 60 U/kg for 4 days, and 100 U/kg for 4 days) or physiological saline. Insulin-injected hamsters under both dietary conditions increased their total caloric consumption by up to 33% and gained significantly more weight than saline-injected controls. Choice hamsters increased their fat intake in response to the 60 and 100 U/kg doses of insulin, but carbohydrate and protein consumption increased only in response to the 100 U/kg dose. Choice hamsters derived approximately 65% of the excess calories ingested during insulin administration from fat, but only 20% from carbohydrate and 15% from protein. Results are related to those previously observed in other species.     

Impaired drinking to angiotensin II after subdiaphragmatic vagotomy in rats

Rats received total bilateral subdiaphragmatic vagotomy and, one month later, were fitted with chronic intravenous or intracerebroventricular cannulas. The vagotomized rats showed much reduced drinking compared with controls during intravenous infusion of angiotensin II. Their drinking to intracerebroventricularly administered angiotensin II was, however, less affected. The possible role of the vagus nerve in the mediation of angiotensin and other types of drinking is discussed.     

Ultrastructural analysis of the adrenal cortex in rats after bilateral subdiaphragmatic vagotomy

Electron-microscopic investigation of the zona fasciculata and zona reticularis of the adrenal cortex in rats showed that 7 days after bilateral subdiaphragmatic vagotomy the perinuclear space of the adrenocorticocytes and endothelial cells is widened, the tubules of the smooth cytoplasmic reticulum are dilated, the mitochondria edematous, their cristae reduced, and the number and size of the lipid droplets diminished. After 45 days some mitochondria were starting to undergo myelinization, lipid droplets were aggregating, and electron-translucent vacuoles appeared in them. Vagotomy depresses the function of the adrenocorticocytes of the zona fasciculata and zona reticularis of the rat adrenal cortex.Department of Histology and Embryology, Faculty of Internal Medicine, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 4, pp. 492–494, April, 1977.     

Physiological regeneration of the jejunal epithelium after bilateral subdiaphragmatic vagotomy in rats

Seven days after bilateral subdiaphragmatic vagotomy in rats the mean diurnal number of mitoses in the jejunal epithelium is increased by 1.5 times. The character of the diurnal rhythm of mitosis is unchanged but fluctuations in the curve of mitotic activity are reduced. Vagotomy does not disturb the ratio between the volumes of cell populations of the villi and crypts, which indicates that the steady state of renewal of the cell composition of the cryptvillus system is maintained under these conditions.Department of Histology and Embryology, Faculty of Internal Medicine, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Kupriyanov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 2, pp. 236–237, February, 1976.     

Hypothalamic hypoactivity prevented but not reversed by subdiaphragmatic vagotomy

Parasagittal hypothalamic knife cuts produce a syndrome which includes obesity and hypoactivity. When the subdiaphragmatic vagi were cut at the same time as the brain cuts were made, both the obesity and the hypoactivity were prevented. This suggested that both the obesity and the hypoactivity are mediated by vagal hyperactivity. In contrast, however, when the subdiaphragmatic vagotomy was done 40–70 days subsequent to the brain cuts, the obesity was reversed, but the hypoactivity persisted. Thus, some aspect of the interoperative period irreversibly prevents the ability of vagotomy to reinstate normal activity levels in the rat.     

Effect of subdiaphragmatic vagotomy on the sodium and potassium distribution in rats

The state of metabolism of sodium and potassium in male rats 1, 7, 14 and 19 days after bilateral subdiaphragmatic vagotomy was investigated by mapping the distribution of the elements in individual organs. Vagotomy was shown to disturb electrolyte metabolism, most severely one and seven days after the operation. Relative normalization of sodium and potassium metabolism was observed after 14 and 19 days.Department of Histology and Embryology, Therapeutic Faculty, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. S. Savel'ev.) Translated from Byulleten'. Éksperimental'noi Biologii i Meditsiny, Vol. 86 No. 11, pp. 528–530, November, 1978.     

Morphometric analysis of pancreatic islets of rats after subdiaphragmatic vagotomy

Analysis of the morphometric data showed that seven days after vagotomy significant disturbances arise in the pancreatic islets, mainly affecting the B cells. In the late stages (45 and 90 days) after the operation some morphological and functional normalization is observed, but full recovery does not take place.Department of Histology and Embryology, Faculty of Internal Medicine, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR A. V. Smol'yannikov.) Translated from Byulleten' Éksperimetal'noi Biologii i Meditsiny, Vol. 88, No. 11, pp. 609–611, November, 1979.