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S Cardin

Publications and source records attributed to S Cardin.

At least 19 recordsLinked to original sources
PubMed2001

Effects of angiotensin-converting enzyme inhibition on the development of the atrial fibrillation substrate in dogs with ventricular tachypacing-induced congestive heart failure.

BACKGROUND: Atrial structural remodeling creates a substrate for atrial fibrillation (AF), but the underlying signal transduction mechanisms are unknown. This study assessed the effects of ACE inhibition on arrhythmogenic atrial remodeling and associated mitogen-activated protein kinase (MAPK) changes in a dog model of congestive heart failure (CHF). METHODS AND RESULTS: Dogs were subjected to various durations of ventricular tachypacing (VTP, 220 to 240 bpm) in the presence or absence of oral enalapril 2 mg. kg(-1). d(-1). VTP for 5 weeks induced CHF, local atrial conduction slowing, and interstitial fibrosis and prolonged atrial burst pacing-induced AF. Atrial angiotensin II concentrations and MAPK expression were increased by tachypacing, with substantial changes in phosphorylated forms of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and p38-kinase. Enalapril significantly reduced tachypacing-induced changes in atrial angiotensin II concentrations and ERK expression. Enalapril also attenuated the effects of CHF on atrial conduction (conduction heterogeneity index reduced from 3.1+/-0.4 to 1.9+/-0.2 ms/mm, P<0.05), atrial fibrosis (from 11.9+/-1.1% to 7.5+/-0.4%, P<0.01), and mean AF duration (from 651+/-164 to 218+/-75 seconds, P<0.05). Vasodilator therapy of a separate group of VTP dogs with hydralazine and isosorbide mononitrate did not alter CHF-induced fibrosis or AF promotion. CONCLUSIONS: CHF-induced increases in angiotensin II content and MAPK activation contribute to arrhythmogenic atrial structural remodeling. ACE inhibition interferes with signal transduction leading to the AF substrate in CHF and may represent a useful new component to AF therapy.

Angiotensin II↗
PubMed2001

Selective tonic inhibition of G-6-Pase catalytic subunit, but not G-6-P transporter, gene expression by insulin in vivo.

The regulation of glucose-6-phosphatase (G-6-Pase) catalytic subunit and glucose 6-phosphate (G-6-P) transporter gene expression by insulin in conscious dogs in vivo and in tissue culture cells in situ were compared. In pancreatic-clamped, euglycemic conscious dogs, a 5-h period of hypoinsulinemia led to a marked increase in hepatic G-6-Pase catalytic subunit mRNA; however, G-6-P transporter mRNA was unchanged. In contrast, a 5-h period of hyperinsulinemia resulted in a suppression of both G-6-Pase catalytic subunit and G-6-P transporter gene expression. Similarly, insulin suppressed G-6-Pase catalytic subunit and G-6-P transporter gene expression in H4IIE hepatoma cells. However, the magnitude of the insulin effect was much greater on G-6-Pase catalytic subunit gene expression and was manifested more rapidly. Furthermore, cAMP stimulated G-6-Pase catalytic subunit expression in H4IIE cells and in primary hepatocytes but had no effect on G-6-P transporter expression. These results suggest that the relative control strengths of the G-6-Pase catalytic subunit and G-6-P transporter in the G-6-Pase reaction are likely to vary depending on the in vivo environment.

Animals↗
PubMed2001

Pancreatic response to mild non-insulin-induced hypoglycemia does not involve extrinsic neural input.

Mild non-insulin-induced hypoglycemia achieved by administration of a glycogen phosphorylase inhibitor results in increased glucagon and decreased insulin secretion in conscious dogs. Our aim was to determine whether the response of the endocrine pancreas to this mild hypoglycemia can occur in the absence of neural input to the pancreas. Seven dogs underwent surgical pancreatic denervation (PDN [study group]), and seven dogs underwent sham denervation (control [CON] group). Each study consisted of a 100-min equilibration period, a 40-min control period, and a 180-min test period. At the start of the test period, Bay R3401 (10 mg/kg), a glycogen phosphorylase inhibitor, was administered orally. Arterial plasma glucose (mmol/l) fell to a similar minimum in CON (5.0 +/- 0.1) and PDN (4.9 +/- 0.3). Arterial plasma insulin also fell to similar minima in both groups (CON, 20 +/- 6 pmol/l; PDN, 14 +/- 5 pmol/l). Arterial plasma glucagon rose to a similar maximum in CON (73 +/- 8 ng/l) and PDN (72 +/- 9 ng/l). Insulin and glucagon secretion data support these plasma hormone results, and there were no significant differences in the responses in CON and PDN for any parameter. Pancreatic norepinephrine content in PDN was only 4% of that in CON, confirming successful sympathetic denervation. Pancreatic polypeptide levels tended to increase in CON and decrease in PDN in response to mild hypoglycemia, indicative of parasympathetic denervation. It thus can be concluded that the responses of alpha- and beta-cells to mild non-insulin-induced hypoglycemia can occur in the absence of extrinsic neural input.

Animals↗
PubMed2001

Effect of vagal cooling on the counterregulatory response to hypoglycemia induced by a low dose of insulin in the conscious dog.

We previously demonstrated, using a nerve-cooling technique, that the vagus nerves are not essential for the counterregulatory response to hypoglycemia caused by high levels of insulin. Because high insulin levels per se augment the central nervous system response to hypoglycemia, the question arises whether afferent nerve fibers traveling along the vagus nerves would play a role in the defense of hypoglycemia in the presence of a more moderate insulin level. To address this issue, we studied two groups of conscious 18-h-fasted dogs with cooling coils previously placed on both vagus nerves. Each study consisted of a 100-min equilibration period, a 40-min basal period, and a 150-min hypoglycemic period. Glucose was lowered using a glycogen phosphorylase inhibitor and a low dose of insulin infused into the portal vein (0.7 mU.kg(-1) min(-1)). The arterial plasma insulin level increased to 15 +/- 2 microU/ml and the plasma glucose level fell to a plateau of 57 +/- 3 mg/dl in both groups. The vagal cooling coils were perfused with a 37 degrees C (SHAM COOL; n = 7) or a -20 degrees C (COOL; n = 7) ethanol solution for the last 90 min of the study to block parasympathetic afferent fibers. Vagal cooling caused a marked increase in the heart rate and blocked the hypoglycemia-induced increase in the arterial pancreatic polypeptide level. The average increments in glucagon (pg/ml), epinephrine (pg/ml), norepinephrine (pg/ml), cortisol (microg/dl), glucose production (mg.kg(-1). min(-1)), and glycerol (micromol/l) in the SHAM COOL group were 53 +/- 9, 625 +/- 186, 131 +/- 48, 4.63 +/- 1.05, -0.79 +/- 0.24, and 101 +/- 18, respectively, and in the COOL group, the increments were 39 +/- 7, 837 +/- 235, 93 +/- 39, 6.28 +/- 1.03 (P < 0.05), -0.80 +/- 0.20, and 73 +/- 29, respectively. Based on these data, we conclude that, even in the absence of high insulin concentrations, afferent signaling via the vagus nerves is not required for a normal counterregulatory response to hypoglycemia.

Animals↗
PubMed2001

Small increases in insulin inhibit hepatic glucose production solely caused by an effect on glycogen metabolism.

Based on our earlier work, a 2.5-fold increase in insulin secretion should completely inhibit hepatic glucose production through the hormone's direct effect on hepatic glycogen metabolism. The aim of the present study was to test the accuracy of this prediction and to confirm that gluconeogenic flux, as measured by three independent techniques, was unaffected by the increase in insulin. A 40-min basal period was followed by a 180-min experimental period in which an increase in insulin was induced, with euglycemia maintained by peripheral glucose infusion. Arterial and hepatic sinusoidal insulin levels increased from 10 +/- 2 to 19 +/- 3 and 20 +/- 4 to 45 +/- 5 microU/ml, respectively. Net hepatic glucose output decreased rapidly from 1.90 +/- 0.13 to 0.23 +/- 0.16 mg. kg(-1). min(-1). Three methods of measuring gluconeogenesis and glycogenolysis were used: 1) the hepatic arteriovenous difference technique (n = 8), 2) the [(14)C]phosphoenolpyruvate technique (n = 4), and 3) the (2)H(2)O technique (n = 4). The net hepatic glycogenolytic rate decreased from 1.72 +/- 0.20 to -0.28 +/- 0.15 mg. kg(-1). min(-1) (P < 0.05), whereas none of the above methods showed a significant change in hepatic gluconeogenic flux (rate of conversion of phosphoenolpyruvate to glucose-6-phosphate). These results indicate that liver glycogenolysis is acutely sensitive to small changes in plasma insulin, whereas gluconeogenic flux is not.

Animals↗
PubMed2000

Prediction of hospital utilization among elderly patients during the 6 months after an emergency department visit.

STUDY OBJECTIVE: A simple screening tool, Identification of Seniors at Risk (ISAR), developed for administration in the emergency department for patients 65 years and older, predicts adverse health outcomes during the 6 months after the ED visit. In this study, we investigated whether the ISAR tool can also predict acute care hospital utilization in the same population. METHODS: Patients 65 years and older who visited the EDs of 4 acute care Montreal hospitals during the weekday shift over a 3-month period were enrolled. At the initial (index) ED visit, 27 self-report screening questions (including the 6 ISAR items) were administered. The number of acute care hospital days during the 6 months after the index visit were abstracted from the provincial hospital discharge database. High utilization was defined as the top decile of the distribution of acute care hospital days. RESULTS: Among 1,620 patients with linked data, a score of 2+ on the ISAR tool predicted high hospital utilization with a sensitivity of 73% and a specificity of 51%; the area under the receiver operating characteristic curve was 0.68. The ISAR tool also performed well in subgroups defined by disposition (admitted versus discharged) and by age (65 to 74 years versus 75 years and older). CONCLUSION: The ISAR tool, a 6-item self-report questionnaire, can be used in the ED to identify elderly patients who will experience high acute care hospital utilization as well as adverse health outcomes.

Aged↗
PubMed2000

Return to the emergency department among elders: patterns and predictors.

OBJECTIVES: 1) To describe the pattern of return visits to the emergency department (ED) among elders over the six months following an index visit; 2) to identify the predictors of early return (within 30 days) and frequent return (three or more return visits in six months); and 3) to evaluate a newly developed screening tool for functional decline, Identification of Seniors At Risk (ISAR), with regard to its ability to predict return visits. METHODS: Subjects were patients aged 65 years or more who visited the EDs of four Canadian hospitals during the weekday shift over a three-month recruitment period. Excluded were patients who: could not be interviewed, due either to their medical conditions or to cognitive impairment, and no other informant was available; refused linkage of study data; or were admitted to hospital at the initial (index) visit. Measures made at the index ED visit included: 27 self-report screening questions on social, physical, and mental risk factors, medical history, use of hospital services, medications, and alcohol. Six of these questions comprised the ISAR scale. Return visits and diagnoses during the six months after the index visit were abstracted from the utilization database. RESULTS: Among 1,122 patients released from the ED, 492 (43.9%) made one or more return visits; 216 (19.3%) returned early and 84 (7.5%) returned frequently. Earlier returns were more likely than later returns to be for the same diagnosis (p = 0.003). Using logistic regression, hospitalization during the previous six months, feeling depressed, and certain diagnoses predicted both early and frequent returns. Also, a history of heart disease, having ever been married, and not drinking alcohol daily predicted early return; a history of diabetes, a recent ED visit, and lack of support predicted frequent use. CONCLUSIONS: In the first month after an ED visit, return rates are highest and are more likely to be for the same diagnosis. Both medical and social factors predict early and frequent returns to the ED; patients at increased risk of return can be quickly identified with a short, self-report questionnaire. The ISAR screening tool, developed to identify patients at increased risk of functional decline, can also identify patients who are more likely to return to the ED.

Aged↗
PubMed2000

Effect of hepatic denervation on the counterregulatory response to insulin-induced hypoglycemia in the dog.

Our aim was to determine whether complete hepatic denervation would affect the hormonal response to insulin-induced hypoglycemia in dogs. Two weeks before study, dogs underwent either hepatic denervation (DN) or sham denervation (CONT). In addition, all dogs had hollow steel coils placed around their vagus nerves. The CONT dogs were used for a single study in which their coils were perfused with 37 degrees C ethanol. The DN dogs were used for two studies in a random manner, one in which their coils were perfused with -20 degrees C ethanol (DN + COOL) and one in which they were perfused with 37 degrees C ethanol (DN). Insulin was infused to create hypoglycemia (51 +/- 3 mg/dl). In response to hypoglycemia in CONT, glucagon, cortisol, epinephrine, norepinephrine, pancreatic polypeptide, glycerol, and hepatic glucose production increased significantly. DN alone had no inhibitory effect on any hormonal or metabolic counterregulatory response to hypoglycemia. Likewise, DN in combination with vagal cooling also had no inhibitory effect on any counterregulatory response except to reduce the arterial plasma pancreatic polypeptide response. These data suggest that afferent signaling from the liver is not required for the normal counterregulatory response to insulin-induced hypoglycemia.

3-Hydroxybutyric Acid↗
PubMed1999

Validity of an activities of daily living questionnaire among older patients in the emergency department.

The objective of this study was to determine the validity of French and English versions of the Older American Resources and Services (OARS) activities of daily living (ADL) questionnaire using a premorbid reference period among older emergency department (ED) patients. A sample of 404 ED patients aged 65 and over participating in a study of functional decline was invited to participate in a clinical assessment shortly after their ED visit. The OARS ADL questionnaire was administered either to the patient or a proxy informant at the ED visit. The clinical assessment was conducted by a nurse, blind to the OARS score, using the Functional Autonomy Measurement System (SMAF). Disability scores for the OARS and SMAF were computed, based on the patient's premorbid status. Assessments were conducted in 213 patients (52.7%). The OARS summary scores, a total and an ordinal score, were highly correlated with the SMAF total disability score (Spearman's r of 0.80 and 0.79, respectively). Similar correlations were found for French and English versions. The OARS ADL questionnaire with a premorbid reference period appears to be valid when administered in the ED, both in French and English.

Activities of Daily Living↗
PubMed1999

Detection of older people at increased risk of adverse health outcomes after an emergency visit: the ISAR screening tool.

OBJECTIVES: To develop a self-report screening tool to identify older people in the emergency department (ED) of a hospital at increased risk of adverse health outcomes, including: death, admission to a nursing home or long-term hospitalization, or a clinically significant decrease in functional status. DESIGN: Prospective (6-month) follow-up study of a cohort of ED patients aged 65 and older. SETTING: The EDs of four acute-care hospitals in Montreal, Quebec, Canada. PARTICIPANTS: Community-dwelling patients aged 65 and older who came to the EDs during the weekday shift over a 3-month recruitment period. Patients were excluded if they could not be interviewed either because of their medical condition or because of cognitive impairment and no other informant was available. MEASUREMENTS: Measures ascertained at the ED visit included: 27 self-report screening questions on social, physical, and mental risk factors; medical history; use of hospital services, medications, and alcohol; and the Older American Resources and Services (OARS) activities of daily living (ADL) scale. At follow-up, the OARS scale was readministered by telephone, and other adverse health outcomes were ascertained. RESULTS: Among 1673 patients who completed the follow-up measures, 488 (29.2%) had an adverse health outcome. Scale development and selection methods included logistic regression, receiver operating characteristic curves, and expert judgment. The proposed screening tool (ISAR) comprises six self-report questions on functional dependence (premorbid and acute change), recent hospitalization, impaired memory and vision, and polymedication. The tool performed well in the total cohort aged 65 and older, and in sub-groups defined by disposition (admitted or released from ED), language of questionnaire administration (French or English), information source (patient or other), and other characteristics. CONCLUSIONS: The ISAR is a short self-report questionnaire that can quickly identify older patients in the ED at increased risk of several adverse health outcomes and those with current disability.

Aged↗
PubMed1999

Duodenal loading with glucose induces fos expression in rat brain: selective blockade by devazepide.

The role of CCK in mediating neuronal activity in the brain in response to dietary carbohydrate was measured by detecting Fos immunoreactivity in response to duodenal glucose load in rats after administration of the CCK-A receptor antagonist devazepide. In adult, male Sprague-Dawley rats, infusion for 30 min of 545 mg (2.18 kcal) dextrose through a duodenal cannula induced Fos expression in the nucleus of the solitary tract (NTS), area postrema (AP), lateral division of the central nucleus of the amygdala (CeAL), and the external subnucleus of the lateral parabrachial nucleus (LPBE). Devazepide treatment (1 mg/kg) attenuated Fos expression in the NTS and AP by 81 and 78%, respectively, but not in the CeAL or LPBE. These results indicate that central neuronal activation is elicited by dietary glucose in the intestinal lumen and that activation of neurons in the NTS and AP is mediated by CCK-A receptors.

Animals↗
PubMed1999

Portal glucose infusion increases hepatic glycogen deposition in conscious unrestrained rats.

It has been demonstrated in the conscious dog that portal glucose infusion creates a signal that increases net hepatic glucose uptake and hepatic glycogen deposition. Experiments leading to an understanding of the mechanism by which this change occurs will be facilitated if this finding can be reproduced in the rat. Rats weighing 275-300 g were implanted with four indwelling catheters (one in the portal vein, one in the left carotid artery, and two in the right jugular vein) that were externalized between the scapulae. The rats were studied in a conscious, unrestrained condition 7 days after surgery, following a 24-h fast. Each experiment consisted of a 30- to 60-min equilibration, a 30-min baseline, and a 120-min test period. In the test period, a pancreatic clamp was performed by using somatostatin, insulin, and glucagon. Glucose was given simultaneously either through the jugular vein to clamp the arterial blood level at 220 mg/dl (Pe low group) or at 250 mg/dl (Pe high group), or via the hepatic portal vein (Po group; 6 mg. kg(-1). min(-1)) and the jugular vein to clamp the arterial blood glucose level to 220 mg/dl. In the test period, the arterial plasma glucagon and insulin levels were not significantly different in the three groups (36 +/- 2, 33 +/- 2, and 30 +/- 2 pg/ml and 1.34 +/- 0.08, 1. 37 +/- 0.18, and 1.66 +/- 0.11 ng/ml in Po, Pe low, and Pe high groups, respectively). The arterial blood glucose levels during the test period were 224 +/- 4 mg/dl for Po, 220 +/- 3 for Pe low, and 255 +/- 2 for Pe high group. The liver glycogen content (micromol glucose/g liver) in the two Pe groups was not statistically different (51 +/- 7 and 65 +/- 8, respectively), whereas the glycogen level in the Po group was significantly greater (93 +/- 9, P < 0.05). Because portal glucose delivery also augments hepatic glycogen deposition in the rat, as it does in the dogs, mechanistic studies relating to its function can now be undertaken in this species.

Animals↗
PubMed1998

Effect of hepatic portal injection of ouabain on the hepato-sympathoadrenal reflex.

The purpose of the present investigation was to evaluate the effects of an intraportal injection of ouabain (2 mg/kg), an inhibitor of the sodium-potassium pump, on plasma catecholamine response in unrestrained normally fed rats with and without an intact hepatic vagus nerve. Three groups of rats were submitted to two injection conditions each. Hepatic vagotomized (HV) rats were randomly injected with ouabain or saline (0.9%) in the portal vein. Sham-operated rats were either injected with ouabain or saline in the portal or jugular vein. Ouabain or saline were injected at 0 min and again at 20 min. Plasma catecholamines were measured before the first injection and 15 min after each injection. Blood glucose concentrations were significantly (p < 0.01) increased by the ouabain injection as compared with basal values and saline-injected groups. The hyperglycemic effect of ouabain was not affected by the hepatic vagotomy or the site of infusion. The injection of ouabain, either into the portal or the jugular vein and either after HV or the sham operation, resulted in a significant (p < 0.01) increase in epinephrine levels as compared with saline-infused rats. Plasma norepinephrine levels were significantly (p < 0.05) increased after the second intraportal injection of ouabain in both HV and sham-operated groups. However, the injection of ouabain into the jugular vein did not change the plasma norepinephrine levels. The latter observation indicates a specific action of ouabain in the liver on the sympathetic activity.

Adrenal Glands↗
PubMed1998

Lack of effects of an acute hepatic vagotomy on insulin and catecholamine responses in rats following exercise.

The purpose of the present investigation was to evaluate the effects of an acute hepatic vagotomy on hormonal responses to hyperglycemic and hypoglycemic challenges in rats previously submitted to an exercise protocol. Two experiments were conducted. In a first experiment, 8-week trained (TR) and untrained (UNTR) rats, subdivided into acutely hepatic vagotomized (HV) and sham-operated (SHM) groups, were submitted to an intraperitoneal glucose tolerance test (0.5 g/kg) under anesthesia. Training was associated with a tendency (P = 0.07) for blood glucose levels to be less elevated (at time point 10 min), and with a significant (P < 0.01) lower glucose/insulin ratio following the glucose injection. The HV did not have any effects on these responses. In a second experiment, non-exercised rats and a group of rats submitted to an acute bout of exercise (treadmill, 60 min, 26 m/min, 5% slope) 24 h before the experiment, each one of these two groups being subdivided into acutely HV and SHM groups, were submitted to an insulin-induced hypoglycemia protocol, under anesthesia. Blood glucose concentrations were decreased significantly (P < 0.01) to approximately 40 mg/dl in all groups 60 and 80 min after the insulin injection. Plasma adrenaline and noradrenaline levels were increased significantly (P < 0.01) in all groups. The catecholamine increase was not influenced by the HV or the acute exercise bout. The present results do not indicate an implication of the hepatic vagus nerve on hormonal responses to hyper and hypoglycemia following exercise.

Animals↗
PubMed1998

Screening for geriatric problems in the emergency department: reliability and validity. Identification of Seniors at Risk (ISAR) Steering Committee.

OBJECTIVE: To determine the test-retest reliability and concurrent criterion validity of a self-report ED screening questionnaire for adverse outcomes in elders. METHODS: A cohort of 1,885 patients aged > or = 65 years were recruited from the EDs of 4 Montreal hospitals. Patients were excluded if they could not be interviewed because of their clinical status or cognitive impairment and no informant was available. The screening questionnaire, administered in the ED, contained 27 items on social, physical, and mental risk factors, medical history, and use of hospital services, medications, and alcohol. A random sample of 404 patients were invited to participate in a clinical assessment 1-3 weeks after the ED visit, that included re-administration of the screening questionnaire, and standardized instruments to assess disability, social resources, depression, alcohol use and abuse, and current medications. RESULTS: Study data were collected from 221 patients (54.7%), of whom 193 were included in the test-retest reliability analyses and 213 in the analyses of concurrent validity. The concordance correlation coefficient for test-retest reliability of the risk factor score was 0.78 (95% confidence interval: 0.71, 0.83; n=193). Several screening questions showed moderately good agreement with the appropriate criterion standard, particularly those on visual and hearing impairment, depression, and use of medications. The best subset of 9 screening questions explained approximately half of the variance in the total disability score. CONCLUSIONS: The screening questionnaire score has good test-retest reliability, but individual screening questions have, at best, modest concurrent validity. The final set of screening questions should be selected based on their predictive validity.

Aged↗
PubMed1997

Effects of vagal blockade on the counterregulatory response to insulin-induced hypoglycemia in the dog.

Our aim was to determine whether vagal transmission is required for the hormonal response to insulin-induced hypoglycemia in 18-h-fasted conscious dogs. Hollow coils were placed around the vagus nerves, with animals under general anesthesia, 2 wk before an experiment. On the day of the study they were perfused with -15 degrees C ethanol for the purpose of blocking vagal transmission, either coincident with the onset of insulin-induced hypoglycemia or after 2 h of established hypoglycemia. In a separate study the coils were perfused with 37 degrees C ethanol in a sham cooling experiment. The following parameters were measured: heart rate, arterial plasma glucose, insulin, pancreatic polypeptide, glucagon, cortisol, epinephrine, norepinephrine, glycerol, free fatty acids, and endogenous glucose production. In response to insulin-induced hypoglycemia (42 mg/dl), plasma glucagon peaked at a level that was double the basal level, and plasma cortisol levels quadrupled. Plasma epinephrine and norepinephrine levels both rose considerably to 2,135 +/- 314 and 537 +/- 122 pg/ml, respectively, as did plasma glycerol (330 +/- 60%) and endogenous glucose production (150 +/- 20%). Plasma free fatty acids peaked at 150 +/- 20% and then returned to basal levels by the end of the study. The hypoglycemia-induced changes were not different when vagal cooling was initiated after the prior establishment of hypoglycemia. Similarly, when vagal cooling occurred concurrently with the initiation of insulin-induced hypoglycemia (46 mg/dl), there were no significant differences in any of the parameters measured compared with the control. Thus vagal blockade did not prevent the effect on either the hormonal or metabolic responses to low blood sugar. Functioning vagal afferent nerves are not required for a normal response to insulin-induced hypoglycemia.

Animals↗
PubMed1996

Intracerebroventricular CRF inhibits cold restraint-induced c-fos expression in the dorsal motor nucleus of the vagus and gastric erosions in rats.

Acute exposure to cold-restraint induces vagal-dependent gastric erosions associated with activation of neurons in the dorsal motor nucleus of the vagus (DMN) in rats. The influence of intracerebroventricular (i.c.v.) injection of corticotropin-releasing factor (CRF) (10 micrograms) on c-fos expression in the brain and gastric erosions induced by 3 h cold-restraint was investigated in conscious rats. In cold-restraint exposed rats, CRF injected i.c.v. inhibited gastric erosions and the number of Fos positive neurons in the DMN by 93 and 72%, respectively, while Fos labelling in the nucleus tractus solitarius (NTS) was increased by 5-fold compared with vehicle group. c-fos expression was also induced in the central amygdala by i.c.v. CRF, unlike the vehicle-injected group exposed to cold-restraint. c-fos expression induced by cold-restraint in the raphe pallidus (Rpa) and paraventricular nucleus of the hypothalamus was not altered by i.c.v. CRF. These data indicate that central CRF-induced gastric protection results from the inhibition of DMN neuronal activity enhanced by cold-restraint. CRF action on DMN neurons may be related to the increase in the NTS and central amygdala inputs leading to inhibition of DMN neurons rather than to the decrease in the excitatory input from the caudal raphe projections to the DMN.

Analysis of Variance↗