Norepinephrine Regulation of Ventromedial Hypothalamic Nucleus Astrocyte Glycogen Metabolism

The catecholamine norepinephrine (NE) links hindbrain metabolic-sensory neurons with key glucostatic control structures in the brain, including the ventromedial hypothalamic nucleus (VMN). In the brain, the glycogen reserve is maintained within the astrocyte cell compartment as an alternative energy source to blood-derived glucose. VMN astrocytes are direct targets for metabolic stimulus-driven noradrenergic signaling due to their adrenergic receptor expression (AR). The current review discusses recent affirmative evidence that neuro-metabolic stability in the VMN may be shaped by NE influence on astrocyte glycogen metabolism and glycogen-derived substrate fuel supply. Noradrenergic modulation of estrogen receptor (ER) control of VMN glycogen phosphorylase (GP) isoform expression supports the interaction of catecholamine and estradiol signals in shaping the physiological stimulus-specific control of astrocyte glycogen mobilization. Sex-dimorphic NE control of glycogen synthase and GP brain versus muscle type proteins may be due, in part, to the dissimilar noradrenergic governance of astrocyte AR and ER variant profiles in males versus females. Forthcoming advances in the understanding of the molecular mechanistic framework for catecholamine stimulus integration with other regulatory inputs to VMN astrocytes will undoubtedly reveal useful new molecular targets in each sex for glycogen mediated defense of neuronal metabolic equilibrium during neuro-glucopenia.

Preliminary study on physicochemical and biochemical stress markers at poultry slaughterhouse

Pre-slaughter stress can result in variations in the glycogen storage and metabolic changes of muscle, responsible for quality poultry meat. Aim of this study was to investigate, as preslaughter stress markers and quality meat, physicochemical (pH), biochemical (muscle glycogen content), and chemical (super oxides free radicals) parameters. The carcass quality, as incidence of individual carcass defects, also was evaluate. A number of 20 broilers was processed with two different electrical stunning: high (250 Hz; 640 mA; 60V) (Lot C or control) and low (150 Hz; 360 mA; 60 V) (Lot A) frequency and intensity, using sinusoidal alternating current. As preliminary results, the use of low frequency and intensity induced faster pH decline post mortem and adequate acidification of pH at 3 hours (6.49 Lot C; 6.37 Lot A), better muscle glycogen reserve (0.770 μl/50mL Lot C; 1.497μl/50mL Lot A), and lightly more rapid muscle oxidation (IDF: 0.109 Lot C; 0.122 Lot A), (FOX: 0.131 MeqO2/kg Lot C; 0.140 MeqO2/kg Lot A). The incidence of individual carcass defects sufficient to cause downgrading or rejection, both in Lot C and Lot A, was generally low. In a multidisciplinary approach, to assess animal welfare and quality poultry meat, additional and feasible parameters should be implemented. Monitoring of pH, muscle glycogen reserve and superoxide free radical production measurements might be markers easier to use, routinely, in practice at abattoir. Further studies are needed to evaluate the usefulness of these parameters.

Study on the effects of electrical stunning parameters for broilers on biochemical and histological markers of stress and meat quality

This study was designed to investigate physicochemical (pH, peroxides) and histological parameters (glycogen reserve, muscle damages), as pre-slaughter stress markers and quality meat evaluators. Ross commercial broilers was processed, either without stunning (NS Lot), or by combining two current levels of 200 mA, 67 V (HV Lot), and 200 mA, 53 V (MV Lot); with two frequencies of 1000 Hz and 800 Hz, using sinusoidal alternating current. The use of high frequency (800 and 1000 Hz) induced the fastest pH decline, already at 3 h postmortem, in Pectoralis major and Quadriceps femoris of MV and HV Lot carcasses (P < 0.05). Moreover HV carcasses showed a lesser production of superoxide free radicals than the NS Lot and MV Lot carcasses (P < 0.05). Changes in the glycogen reserve and the histological muscle damages did not show significant differences in the analysed Lots. The incidence of individual carcass defects, sufficient to cause downgrading or rejection was generally low in each Lot. To assess animal welfare and quality poultry meat the pH monitoring and measurement of superoxide radical production, as additional and feasible parameters, might be markers easier to use in practice at abattoir.

Vibriosis in Farm Reared White Shrimp, Litopenaeus Vannamei in Andhra Pradesh-Natural Occurrence and Artificial Challenge

In the present study, a total of five species of Vibrio bacteria were isolated from diseased shrimp, Litopenaeus vannamei, collected from commercial shrimp cultured ponds of Eethamukkala, Chinaganjam and Pedaganjam areas, Prakasam district, Andhra Pradesh. The isolated bacterial species were identified as Vibrio parahaemolyticus, Vibrio harveyi, Vibrio alginolyticus, Vibrio mimicus and Vibrio vulnificus. The symptoms shown by diseased shrimps include loss of appetite, red coloration of the body and pleopods, gills often appear red to brown in colour, reduced feeding, empty gut and general septicemia. In diseased shrimp, hepatopancrocytes may appear poorly vacuolated, indicating low lipid and glycogen reserve. In affected shrimps, localized lesions were also observed in the cuticle. Experimental infection trials reveals that V. parahaemolyticus is highly pathogenic to L. vannamei while V. harveyi found to be moderate pathogenic to challenged shrimp and remaining three bacterial species namely V.alginolyticus, V.mimicus and V.vulnificus were less pathogenic in nature.Int J Appl Sci Biotechnol, Vol 4(2): 217-222

Death of schistosome cercariae during penetration of the skin

The seagull, a natural host ofAustrobilharzia terrigalensis, was infected with cercariae through a small area of breast skin; 40% of the schistosomula recovered from the skin shortly afterwards were dead. In budgerigar skin 29% of the schistosomula were dead, but mortality in the skin of ducklings was much higher (85%). The budgerigar is a useful laboratory host for this schistosome, but ducklings are completely resistant to experimental infection mainly because of the barrier effect of the skin.Rapid recovery of schistosomula from budgerigar skin established that the majority of deaths occurred during the first 15 min after application of cercariae. In sections of skin fixed after 10 min nearly all the schistosomula were in the epidermis between the narrowstratum corneumand the living cells of the Malpighian layer. In seagull and budgerigar skin most schistosomula succeeded in crossing the Malpighian layer in the next 5 min, but in ducklings nearly all schistosomula completely failed to penetrate this layer.In vitroexperiments in which cercariae were allowed to penetrate through several layers of dead epidermis, isolated from dried budgerigar skin, into balanced saline, showed that schistosomula are not killed by host cells or a soluble toxic substance. The possibility that the epidermis contains an insoluble toxic substance could not be excluded.The proportion of schistosomula which died during penetration of dead epidermis was related to the number of layers in the barrier, suggesting that schistosomula may die owing to exhaustion caused by the intense activity of penetration.About 30% of the glycogen reserves of cercariae were utilized during penetration of budgerigar skin. In dead schistosomula the glycogen reserve had been reduced by 80%, but the significance of this observation is uncertain because much of the glycogen may have been autolysed after death of the schistosomula. Exposure of cercariae to glucose before penetration did not affect the proportion which died in the skin.Schistosomula adapt to the osmotic pressure in the skin, which is one-third that of sea water, and 30 min after penetration they are rapidly killed if returned to sea water. This process of adaptation is not related to mortality of schistosomula during penetration of the skin.We wish to acknowledge the expert technical assistance of Mrs J. Morgan. This investigation was supported in part by research grant AI-04707 from the National Institute of Allergy and Infectious Diseases, United States Public Health Service.

TOTAL GLYCOGEN IN THE PEA APHID, ACYRTHOSIPHON PISUM (HARR.) (HOMOPTERA, APHIDIDAE)

In the pea aphid, Acyrthosiphon pisum (Harr.), the amount of glycogen increases steadily as the aphid grows from larval to adult stage. The newly born larva, however, lacks the glycogen reserve.

BIOCHEMICAL CHANGES DURING ACUTE PHYSIOLOGICAL FAILURE IN THE RAT: II. THE BEHAVIOR OF ADENINE AND PYRIDINE NUCLEOTIDES OF THE LIVER DURING SHOCK

The acute hypoxia, caused by severe blood loss, gives rise to the rapid breakdown of glycogen in the liver and concurrent increase in the concentration of ATP in the mitochondria. The increase in adenosine triphosphate (ATP) continues until the onset of the reversible phase of shock. The glycogen reserve approaches depletion during the late reversible phase. Simultaneously, the generation of ATP in the mitochondria ceases and the concentration begins to fall. It would appear that at this time the adenylate kinase mechanism in the mitochondrial membrane comes into play to convert the adenosine diphosphate (ADP) into ATP and adenosine monophosphate (AMP). As the condition becomes irreversible the residual ATP and phosphorylated intermediates of the Embden–Meyerhof system undergo rapid hydrolysis with liberation of AMP and inorganic phosphate in the cytoplasm.The concentration of the pyridine nucleotides undergoes no change in any of the liver cell components until the onset of the irreversible phase of failure. Thereafter, these nucleotides undergo a progressive conversion to the reduced form.

HYPOGLYCEMIA IN NEONATAL PERIOD

RECOGNITION of the relative instability of the concentration of glucose in the infant's blood during the initial hours after delivery has stimulated study and consideration of the factors that influence the concentration of glucose during the neonatal period. The increased use by pediatric chemistry laboratories of the Somogyi-Nelson sugar method, which measures true glucose concentration and which gives a lower range of values compared to the older Folin-Wu technique, has intensified the interest in the problem of hypoglycemia of the newborn infant. The glucose concentration in blood depends upon the balance between entry (from placental, alimentary or hepatic sources) and removal (by peripheral utilization). The principal factors concern placental transfer of maternal glucose prior to separation of the cord, hepatic glycogen reserve, hepatic responsiveness and peripheral uptake.

Viability and glycogen reserves in the newly liberated larvae of Ostrea edulis L.

Samples of twelve broods of oyster larvae were subjected to a standard laboratory rearing technique while other samples were assayed for glycogen. The glycogen reserves of the larvae at liberation lay between 13·4 and 15·4% of the dry organic matter. No correlation was observed between the glycogen reserve and either the size of the larvae at liberation or the yield of spat in the rearing experiments

EFFECT OF ANTE-MORTEM TREATMENT OF PIGS ON THE QUALITY OF WILTSHIRE BACON

Meat from pigs slaughtered in a fatigued condition, as in present packing house procedures, had a lower glycogen reserve than meat from animals that had been fed and rested. Post-mortem breakdown of glycogen to lactic acid lowered the pH of meat from fed animals to approximately 5.3 while that from fatigued animals remained at about 6.0 or even as high as 6.6. Meat of low pH contained less sodium nitrite immediately after cure, and retained the desirable red color of cut lean surfaces much longer than did meal of high pH. Meal of low pH was also less susceptible to spoilage by bacteria. Color differences were less apparent after the meat had been smoked, and the preslaughter treatment of the pigs is therefore of less importance in the production of smoked products. The quality of unsmoked Wiltshire skies, on the other hand, would be greatly improved by proper preslaughter handling of the pigs.