The effect of acute restraint stress on regional brain neurotransmitter levels in stress-susceptible pietrain pigs.

Concentrations of noradrenaline (NA), adrenaline (A), dopamine (DA), 5-hydroxytryptamine (5-HT), the DA metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) and the main 5-HT metabolite 5-hydroxyindole-3-acetic acid (5-HIAA) were measured using HPLC in 16 brain areas of control and immobilized Pietrain pigs. The animals were immobilized for 15, 30 and 60 min in the prone position. Control pigs showed patterns of regional distribution of brain monoamines similar to those described for rats, dogs and Duroc pigs. However, the absolute values of NA and A in the hypothalamus and preoptic area were much higher than those in rats and dogs, but similar to those in Duroc pigs. The concentrations of dopamine and its metabolites DOPAC and HVA were highest in the caudate nucleus, the nucleus accumbens, the olfactory tubercle and the ventral tegmental area. The distributions of serotonin and its metabolite 5-HIAA were similar in all examined structures. DOPAC/DA and HVA/DA ratios were higher in the cornu ammonis, the hippocampus posterior and the raphe nuclei than in other structures, which suggests brain structure-related differences in dopamine turnover. The greatest decreases in NA and A content were observed in the hypothalamus, the preoptic area and the olfactory tuberculum during the first 30 min of immobilization stress. 5-HT turnover was increased in the raphe nuclei, while DA turnover was affected in the raphe nuclei, the septum, the substantia nigra and the olfactory tubercle. We suggest that acute immobilization stress caused differences in regional patterns of brain biogenic amines, thereby maintaining adequate transmitter levels during stress in stress-susceptible pigs.

The influence of restraint immobilization stress on the concentration qf bioamines and cortisol in plasma of Pietrain and Duroc pigs.

Forty-five Duroc (recognized as not susceptible to stress) and 34 Pietrain (susceptible to stress) pigs were subjected to immobilization stress in a prone position for 5, 15, 30 and 60 min. Plasma concentrations of epinephrine (E), norepinephrine (NE), dopamine (DA) and cortisol (C) were determined in response to restraint stress. The concentrations of E, NE and DA were different between the two strains of pigs (some significant interactions); the highest response was seen after 5 min of stress. The concentration of plasma C increased with duration of stress and there was a significant interaction between strain of animals and the time of stress. Our data substantiate the use of E, NE, DA and C as indicators of stress in swine as early as 5 min after exposure to the stressor. It is also shown that stress-susceptible Pietrain pigs had higher plasma concentrations of E, NE and DA than Duroc pigs.

Alterations of brain monoamine levels in pigs exposed to acute immobilization stress.

Concentrations of noradrenaline (NA), adrenaline (A), dopamine (DA) and 5-hydroxytryptamine (5-HT), as well as DA metabolites 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and the main 5HT metabolite, 5-hydroxyindole-3-acetic acid (5-HIAA), were measured using the HPLC technique in 15 brain areas of control and immobilized Duroc pigs. The animals were immobilized for 5, 15, 30 and 60 min in a prone position. Control pigs displayed patterns of regional distribution of brain monoamines similar to those described in other species, especially rats and dogs. However, absolute values of noradrenaline and adrenaline in the hypothalamus were much higher than in other species. Also, in most structures, the DOPAC/DA ratio was relatively high, in comparison to a relatively low HVA/DA ratio, which suggests a species-related difference in the turnover of dopamine. The most conspicuous changes produced by immobilization stress consisted of a substantial decrease in the hypothalamic levels of noradrenaline and adrenaline. Dopamine and 5-HT turnover was affected in the hippocampus (cornu Ammonis), and in the raphe nuclei. These structures are proposed to play a major role in the responsiveness of pigs to acute stress conditions.

Glucagon effect on glycogen content of chicken liver and muscles.

The experiments were carried out on broiler chickens divided randomly into two groups differing in the feeding level and, consequently, in the rate of weight gain. Half the chickens in each group were given a single dose of glucagon 150 micrograms/kg, and the other half received a control solution of glycine buffer. The chickens were investigated 1--1.5 hour after feeding and after 18--20 hours of starvation using the technique of biopsy of the liver and the external pectoral muscle. In the biopsy specimens the glycogen level was determined immediately before glucagon administration and 30--60--90 minutes after the injection. It was found that glucagon injection caused either a rise or a fall in the glycogen level in the liver and that the trend of these changes depended on the feeding level of the chickens and on the duration of starvation of the birds before treatment. The glycogen level in the pectoral muscle of the chickens kept on the higher feeding level was observed to fall one hour after glucagon administration.

The effect of propylthiouracil (PTU) on heat production in chickens maintained on different levels of nutrition.

Using the method of forced feeding on higher and lower levels, two groups of chickens differring in growth rate were obtained. In the chickens of the two groups 72 measurements of heat production were made. Chickens of these groups were compared considering either the same age or similar body weight. It has been found that propythiouracil treatment (120 mg/kg duging 10 consecutive days) decreases heat production in the chickens of both groups. However, this effect was much more pronounced in the birds maintained on the higher level of nutrition and growing more rapidly than in those maintained on the lower level of nutrition and growing slowly.