Diazepam attenuation of restraint stress-induced corticosterone levels is enhanced by prior exposure to repeated restraint.

Prior research has demonstrated that diazepam decreases hypothalamic-pituitary-adrenal cortex (HPA) axis activity in stressful contexts but, paradoxically, acts as a stimulator of basal axis activity. Also, several investigators have reported that low doses of diazepam are not effective in reducing stress-induced corticosterone (CORT) levels, yet similar doses typically produce anxiolytic effects on behavioral measures of fear and anxiety. We have examined the effects of diazepam on plasma CORT levels in male Sprague-Dawley rats utilizing a repeated restraint paradigm. Consistent with most literature, diazepam administered IP (1.5, 3.0, or 6.0 mg/kg) 1 h prior to restraint increased non-stress, baseline plasma CORT levels in a dose-dependent fashion. During the first exposure to the 1 h restraint-stress procedure, CORT levels of diazepam-injected rats did not differ from the stress levels of controls except at the 60-min stress time point in those subjects receiving 6.0 mg/kg. However, diazepam at all three doses was able to attenuate the stress-induced increase in CORT following 5 days of diazepam+restraint treatment. Using the 3.0 mg/kg dose as a probe, it was found that this effect was not dependent on the repeated administration of diazepam, but rather on repeated exposure to restraint. These results suggest that repeated restraint produces a change in neural sensitivity to benzodiazepines.

Effects of norepinephrine infusion and exercise on blood pressure in rats.

Two experiments were conducted to test the hypotheses that norepinephrine (NE) infusion would increase blood pressure and wheel running activity level, and, secondly, that voluntary exercise would lower NE-induced increases in blood pressure. NE-bitartrate was infused into male Sprague-Dawley rats using an implanted osmotic pump (3.75 micrograms/kg/min in 0.9% saline). Control rats received the vehicle solution. Systolic blood pressure was measured by the tail-cuff method. Voluntary wheel running activity expressed as wheel revolutions per 24 hr was measured on the 5th, 9th, and 13th day. Blood pressure on the 13th day and wheel running activity on the 9th day were significantly higher in NE-infused rats. The NE content of heart tissue was not altered, but urinary excretion of NE and epinephrine was increased in the NE-infused animals. Food intake, body weight gain, and kidney weight per 100 g body wt were not changed but heart weight per 100 g body wt was increased by NE infusion. Urinary total calcium excretion was higher in the NE-infused rats. Spontaneous voluntary exercise in running wheels attenuated increases of blood pressure in NE-infused rats. The results of the present study suggest that rats receiving exogenous NE exhibit increased blood pressure and voluntary wheel running activity. Voluntary wheel running exercise also reduces blood pressure in NE-infused rats.

Increased arterial potassium transport in reduced renal mass hypertension of the rat.

Aortic potassium turnover was studied during the development of hypertension induced by salt load in male rats after 70-75% of total renal mass was removed. Systolic blood pressure in the saline-drinking experimental reduced renal mass (RRM) rats steadily increased until the fourth week after surgery and thereafter stayed at the same level. Control RRM rats given tap water for drinking, and unilaterally nephrectomized saline-drinking control rats maintained normal blood pressure. Compared to controls, experimental RRM rats exhibited increased plasma aldosterone concentration while plasma renin activity was low in all groups with no significant difference. Aortic hypertrophy, greater 42K turnover, and elevated 42K exchange were observed with experimental RRM hypertension. Sensitivity to the effect of norepinephrine (NE) on aortic 42K turnover was increased four- to ninefold in the experimental RRM group as compared to controls. These results indicate that reduced renal mass hypertension is associated with increased potassium permeability and NE supersensitivity in vascular smooth muscle.

Effect of low protein diets for growing Leghorn pullets upon subsequent laying performance.

An experiment was conducted with White Leghorn pullets to study the effect on laying performance of dietary protein content and amino acid supplementation during the growing period. From 0 to 6 weeks of age birds fed on diets containing either 149 g protein/kg supplemented with methionine and lysine or 182 g protein/kg grew faster than those fed on a diet containing 149 g protein/kg alone. However, only those fed on the supplemented diet utilised their food more efficiently. From 7 to 20 weeks of age neither body weight gain nor food utilisation was affected by the dietary protein content. Pullets fed the low protein diet supplemented with 2 g methionine/kg and 2.5 g lysine/kg during the period of 0 to 6 weeks of age had significantly better egg production than birds fed the low protein diet alone. The dietary protein content during 7 to 20 weeks of age did not influence subsequent egg production.

The effect of reduced dietary protein on the anterior latissimus dorsi muscle fibers in the Single Comb White Leghorn pullet.

Twenty-four female Single Comb White Leghorn pullets were used to investigate the effect of two levels of dietary protein on fiber number and size of the anterior latissimus dorsi muscle (ALD). The pullets were randomly assigned to a control group of 18% dietary protein or an experimental group of 14% dietary protein at 1 day of age. They were maintained on these diets until 4 weeks of age, at which time they were sacrificed by cervical dislocation. The ALD muscle was removed and analyzed for fiber number, fiber dry weight, and fiber dry weight to muscle wet weight ratio. Muscle fiber number was determined by a direct count of all the fibers following nitric acid digestion. After counting, the muscle fibers were dried to a constant weight for determination of mean fiber dry weight and fiber dry weight to muscle wet weight ratio. Muscle weight of the control group was 39.8% greater than that of the experimental group. Fiber number was not different between control and experimental groups; whereas mean fiber dry weight was 59.6% greater in the control group (P less than .05). Fiber dry weight to muscle wet weight ratio was 7.3% greater in the control group (P less than .05). The data indicate that when growth of the ALD muscle is restricted by low dietary protein content, there is a reduced growth of the individual muscle fibers with no alteration in their number.

Effects of garlic on lipid metabolism in rats fed cholesterol or lard.

Effects of garlic on lipid metabolism were studied in three experiments using different aged male rats fed a diet containing 1% cholesterol or 15% lard. Lyophilized garlic was supplemented at 2% and 4% of the diet. Plasma glucose was not changed by dietary treatments. Rats fed cholesterol and lard diets increased plasma cholesterol and triglycerides compared to controls. Garlic decreased plasma cholesterol in cholesterol- and lard-fed rats, but decreased plasma triglycerides only in the lard-fed group. Garlic supplementation decreased very low density lipoprotein cholesterol and increased high density lipoprotein cholesterol. The liver weight, total liver lipid and cholesterol were increased in rats fed the cholesterol diet but a supplementation of garlic decreased those parameters by about 30%. Dietary cholesterol and lard decreased hepatic glucose-6-phosphate dehydrogenase and malic enzyme activities: the garlic supplementation further decreased these enzyme activities. Garlic feeding increased the excretion of the neutral steroids in both 16-week and 10-week-old rats and bile acids in only 16-week-old pair-fed rats. Garlic at the 2% level was similarly effective on lipid metabolism as at 4%. These results demonstrate that garlic increases the excretion of neutral and acidic steroids and exerts hypocholesterolemic effects in cholesterol-fed rats.

Clinical signs found in association with nutritional deficiencies as related to race, sex, and age for adults.

Clinical signs of various nutritional deficiencies for 429 adults were compared by race, age, and sex. The nutrients studied were vitamin A, riboflavin, vitamin C, vitamin D, and calcium. The prevalence of clinical signs of deficiency for all nutrients was much higher in blacks than in whites. Clinical lesions due to multiple nutrient deficiencies showed the same racial difference. Men had a higher prevalence of clinical signs for all nutrient deficiencies, except for vitamin A, that did the young. The racial and age differences in the nutritional status may be explained by the difference of educational and income levels. In comparison to the results reported from the Health and Nutrition Examination Survey (HANES), 1971 to 1974, the white subjects in this study had slightly higher prevalences of clinical signs than did those in HANES. Also, the prevalence of these clinical signs is much higher in the black subjects of the present study than in those of HANES.

Effects of T-2 toxin on brain catecholamines and selected blood components in growing chickens.

Four-week-old male broiler chickens were intubated with a single dose of purified T-2 toxin at 2.5 mg/kg body weight. The brain concentrations of dopamine (DA), norepinephrine (NE), and serotonin (5-HT) and selected blood components were determined in T-2 toxin treated and control chickens at 4, 12, 24, and 48 hr after the toxin treatment. The brain DA concentration of T-2 treated chickens was significantly greater at 12 and 24 hr, whereas brain NE was lower at 24 and 48 hr after toxin treatment as compared with controls. The brain 5-HT level was not altered by T-2 toxin. Serum cholesterol was increased at 4 and 12 hr after T-2 treatment. The serum LDH and GOT activities were not changed by T-2 toxin. T-2 treated chickens had greater packed cell volume and hemoglobin than controls at 24 hr after dosing. Red blood cell counts were not affected but white blood cell counts were decreased during the 12 to 48 hr period after T-2 treatment. The results of this study suggest that T-2 toxin influences brain catecholamines and blood components and thereby possibly brain function in chickens.

Comparison of selected blood components by race, sex, and age.

The effects of race, age, and sex on selected blood components for 429 black and white adults over 34 year in southwest Mississippi were studied. Fasting blood was collected early in the morning. Whole blood was used for the determination of hematocrit and hemoglobin. The sera were used for the analysis of iron, glucose, triglycerides, cholesterol, vitamin C, alkaline phosphatase, and protein and its fractions such as albumin, alpha-, beta-, and gamma-globulins. The data of whites versus blacks, males versus females, and those under versus over 60 years were compared. A significant racial difference was observed for all selected blood components except alpha-1-globulin, cholesterol, and alkaline phosphatase. Albumin, alpha-2-globulin, hemoglobin, hematocrit, serum iron, triglycerides, and vitamin C were significantly higher in whites than in blacks and total protein, beta-1- and gamma-globulins and glucose were significantly higher in blacks than in whites. Males had higher levels of alpha-1- and gamma-globulins, hemoglobin, and hematocrit, and females had higher levels of cholesterol and alkaline phosphatase. Those 60 years and over had higher gamma-globulin and alkaline phosphatase, while adults under 60 years had higher hematocrit. Although results of this study showed significant differences between the races for certain blood parameters and suggest that these differences should be considered in determining guidelines for nutritional evaluation and criteria of diagnosing diseases, further studies are needed to determine the contributions of environment, economic status, and nutritional status to these differences.

Effect of zearalenone on female White Leghorn chickens.

Acute toxic effects of purified zearalenone were studied in growing female White Leghorn chickens. In the first experiment, zearalenone in gelatin capsules was administered to 10 chickens (zearalenone-treated chickens [ZC]) in a single oral dose of 15.0 g/kg. Another 10 control chickens (CC) received empty gelatin capsules. All chickens survived the 10-day experiment and did not show any noticeable gross or histopathological lesions. There were no differences between CC and ZC in weight gain, oviduct, comb and liver weights, hematological parameters, and serum cholesterol. ZC had significantly less (P less than 0.05) serum calcium but significantly greater (P less than 0.01) serum phosphorus than CC. In the second experiment, zearalenone was administered orally or intramuscularly (pectoral muscle) at levels of 0, 50, 200, 400, and 800 mg/kg for 7 consecutive days. The oviduct weight increased with increasing toxin levels in both orally (OZC) and intramuscularly (IZC) administered groups: there were more pronounced effects in the IZC. The liver weight increased and comb weight decreased in IZC. The relative estrogenic biopotency of zearalenone in IZC, using estradiol dipropionate as a standard, was 1.37%. The results of this experiment demonstrate that chickens are highly tolerant to zearalenone and that the estrogenic effects of the toxin are greater when it is administered in multiple doses than in a single dose and in IZC than in OZC.

Transmission of radioactivity into eggs from laying hens (Gallus domesticus) administered tritium labeled T-2 toxin.

The transmission of radioactivity into eggs from laying hens gastric-intubated with a single or multiple dose of 3-[3H]-T-2 toxin was investigated. In single dosed birds, the maximum radioactivity in eggs occurred at 24 hr after dosing; the yolk and white contained .04 and .13% of the administered radioactivity, respectively. In multiple-dosed birds given 8 consecutive daily doses, the radioactivity in the yolk increased with each dose, whereas the radioactivity in the white increased rapidly until the 3rd dose and thereafter remained constant. In both single- and multiple-dosed birds, the specific radioactivity of the white was greater than that of the yolk. The amount of residue transmitted into an egg in birds intubated daily with 1 mg T-2/kg for 8-consecutive days equivalent to 1.6 ppm dietary T-2) was about .9 microgram (based on specific radioactivity).

Acquired resistance in turkey poults to Pasteurella multocida (P-1059 strain) during aflatoxin consumption.

The potential for impairment by aflatoxin of the development of acquired immunity to fowl cholera in 8 week old turkey poults from a commercial flock was investigated by challenge of vaccinated poults at 10, 12, and 16 weeks of age. Sixty poults were allotted to 4 groups: A) aflatoxin fed, nonvaccinated; B) aflatoxin fed, vaccinated; C) control fed, nonvaccinated; and D) control fed, vaccinated. Aflatoxin B-1 (.5 ppm) was added to the control ration of groups A and B from 49 to 70 days of age. The avirulent CU (Clemson University) strain of Pasteurella multocida drinking water vaccine was given for one day to groups B and C. Challenge (5 poults from each group) was by administration of the virulent (P-1059) strain of P. multocida in the drinking water for 4 consecutive days. The presence of aflatoxin B-1 (.5 ppm) in the feed during oral vaccination with the avirulent strain of P. multocida did not impair the development of acquired resistance to later challenge with the virulent strain. Results indicate that age of poults and method of vaccination may be important factors in the development of acquired resistance to fowl cholera when aflatoxin is present in the diet.

Necrotic oral lesions in chickens fed diacetoxyscirpenol, T-2 toxin, and crotocin.

One-day-old broiler chicks were fed a diet containing either 5 ppm diacetoxyscirpenol (DAS), 5 ppm T-2 toxin, 10 ppm crotocin, or a control diet for 3 weeks. Chicks fed the diet containing DAS and T-2 toxin showed yellowish plaque-type lesions on the beak, tongue, and angle of the mouth. Crotocin did not cause such lesions nor any apparent clinical signs. Chicks fed DAS had the lowest weight gain followed by the T-2, crotocin, and control group in that order; however, chicks fed crotocin had the poorest feed conversion ratio.

Acute toxicity of 12,13-epoxytrichothecenes in one-day-old broiler chicks.

Acute toxic effects of several 12,13-epoxytrichothecenes were investigated in 1-day-old broiler chicks by single oral doses. The 7-day median lethal dose values of purified 8-acetylneosolaniol, diacetoxyscirpenol, T-2 toxin, HT-2 toxin, neosolaniol, deacetyl-HT-2 toxin, and T-2 tetraol were 3.22 +/- 0.26, 3.82 +/- 0.40, 4.97 +/- 0.44, 7.22 +/- 0.39, 24.87 +/- 2.64, 30.18 +/- 7.53 (incomplete value), and 33.79 +/- 5.39 mg/kg of body weight, respectively. Deaths occurred during the 8- to 60-h period after dosing with the tested trichothecenes. Within 4 to 10 h after dosing, inappetence, asthenia, diarrhea, and coma generally developed. Sublethal doses of each toxin decreased feed consumption and weight gain proportionally with the amounts of toxins administered. These results demonstrate that the toxic potency of 12,13-epoxytrichothecenes varies depending on the modification of side chains in the molecule.