Identification of immunoreactive plasma and stomach ghrelin, and expression of stomach ghrelin mRNA in the bullfrog, Rana catesbeiana

In this study, we established a radioimmunoassay (RIA) specific for ghrelin from the bullfrog Rana catesbeiana using a novel antibody raised against the C-terminal amino acid sequence of bullfrog ghrelin [13-28]. We also examined the distribution of ghrelin-producing cells in the stomachs of bullfrogs using this antibody and a cRNA probe specific for the bullfrog ghrelin gene. Ghrelin levels in plasma and stomach extracts were approximately 150 fmol/ml and 83-135 fmol/mg wet tissue, respectively. Reverse-phase high performance liquid chromatographic analysis, combined with bullfrog ghrelin RIA, revealed that ghrelin immunoreactivity in the stomach was composed of non-acylated ghrelin (des-acyl ghrelin) and several acylated forms of ghrelin bearing different fatty acid modifications, which could induce increases in intracellular Ca2+ in cells expressing the rat GH secretagogue receptor. In the stomach, the major storage form was acylated ghrelin. In bullfrog plasma, however, the majority of ghrelin immunoreactivity was des-acyl ghrelin and C-terminal fragments of frog ghrelin. Acylated ghrelin forms comprised only minor peaks. Ghrelin-immunopositive and ghrelin mRNA-expressing cells were observed within the mucosal layer of the stomach. Following starvation, significant increases in plasma ghrelin levels and stomach ghrelin mRNA levels were observed as early as 10 days after starvation. These results indicate that ghrelin is present in the stomach and plasma of the bullfrog, which can be detected with our novel antibody. Interestingly, the primary storage form of ghrelin in the stomach differed from the circulating form dominating in the plasma. Furthermore, increases in ghrelin levels in plasma and mRNA levels in the stomach after starvation suggest the possible involvement of ghrelin in energy homeostasis in the bullfrog.     

Applying fenoxycarb at the penultimate instar triggers an additional ecdysteroid surge and induces perfect extra larval molting in the silkworm

When the juvenile hormone analog fenoxycarb was topically applied to the silkworm Bombyx mori at the beginning of the 3rd or 4th (penultimate) instar, an extra larval molt was induced. The 5th instar period was shortened to about 5 days and the extra 6th instar ranged from 8 to more than 20 days, depending on the dose applied. Starvation before fenoxycarb treatment strongly enhanced the incidence of extra molting up to 100%. When 1 ng was applied in the 4th instar after a 2-day starvation, most larvae underwent an extra molt, metamorphosed to pupae, then to fertile adults. Combining starvation and fenoxycarb application thus induces a perfect extra molt efficiently. In perfect extra molting larvae, profiles of total ecdysteroid titer during the 4th and 5th instars were similar to that during the 4th instar in the control, and the ecdysteroid profile during the extra 6th instar was similar to that during the control 5th (last) instar. At ecdysteroid peaks, 20-hydroxyecdysone (20E) and ecdysone (E), generally regarded as the active molting hormone and its precursor, had similar titers in the 6th instar, whereas E was much less than 20E in the 4th and 5th instars in the extra molting larvae. E was also abundant only in the last larval instar in the control. These results suggest that both 20E and E contents are important for regulation of larval molt and metamorphosis in silkworms and that fenoxycarb triggers the extra molt by inducing an additional larval molt type of ecdysteroid surge before the last larval instar.     

Nutritional requirements based on substrate fluxes in trauma

The metabolic requirements of the severely injured patient dictate the appropriate nutritional support. There is an increase in energy expenditure by the injured person that is associated with increased protein catabolism. The injured patient also utilizes increased amounts of carbohydrate and lipid. The proportions of carbohydrate and lipid utilized appear to depend on the relative amount of calories provided to the injured subject. Measurement of energy expenditure in patients receiving glucose indicates that at most 60% of the expired CO₂ is derived from glucose oxidation. Because protein oxidation contributes approximately 20% of the expired CO₂, lipid oxidation contributes the remaining 20% of the expired CO₂. Therefore, the injured patient should be provided with sufficient calories in the proportion 60% glucose, 20% protein, and 20% lipid.     

Drug and food-deprivation modulation of activity in rats given chronic dietary lead: Significance of type of activity measure

In Experiment 1, rats were given a 1% lead acetate diet from Day 100 of life to the termination of the experiment. After 82 days of lead feeding behavioral tests were started. Lead exposure increased wheel-turning hyperactivity produced by food deprivation and phenylethylamine injection. Lead produced no activity change in the unchallenged condition. In the open field, lead-exposed rats were less responsive to the stimulating action of PEA and amphetamine and to the sedating action of pentobarbital. In Experiment 2, the interaction of lead with food deprivation or PEA on wheel-turning was replicated in naive animals given only a 32-day exposure. Chemical analysis was made of tissues. Ingested lead entered the brain. Regional steady-state levels of brain norepinephrine, dopamine and serotonin were not altered by lead treatment when measured following four days of starvation at a time when lead-induced behavioral change was distinct. It was concluded that pharmacological challenges on activity may be sensitive indicators of lead exposure, but the type of activity measure is critical.     

Effects of phenobarbitone and starving on the dopamine content of the adrenal glands of rats exposed to carbon disulphide

Summary Two 4 h inhalation exposures of male rats to 2.0 mg/l CS₂ given on consecutive days increased the dopamine (DA) content of the adrenal gland by 100%. In rats treated with phenobarbitone (Phb) or starved before exposure the increase in adrenal DA was significantly higher. The highest DA content in adrenal glands was found in starved phenobarbitone pretreated rats after CS₂ exposure. Starvation and/or phenobarbitone without CS₂ exposure caused no increase in adrenal DA.     

Gender and energy balance: Sex differences in adaptations for feast and famine

According to this theory/review, the cross-culturally common finding of more women than men among the obese is at least in part a consequence of sex differences in evolutionary selection pressures. James and Trayhurn claim that the propensity to obesity is linked to the ability to survive a fast and both may involve reduced heat production. The present theory extends this relationship to sex differences in energy balance. According to the theory proposed here, mammalian females were subjected to more severe selection pressures during times of short food supply than males were and hence females were under more pressure to evolve mechanisms to facilitate survival during famine, which led to sex differences in obesity. The data relevant to sex differences in starvation survival, obesity and heat production, and the possible evolutionary roles and implications of sex differences in chromosomes and in organizational and activational sex hormones are reviewed. The conclusion is that evolution has created a linkage between sex chromosomes, hormones and energy balance, and this linkage is at least in part responsible for the greater resistance of the female to famine and for her greater tendency to become obese in times of feast.     

Fatty acid metabolism via triglyceride in the salmon heart.

The composition of heart lipids was analyzed and the metabolism of heart triglycerides investigated in pre- and post-spawning pink salmon (Oncorhyncus gorbuscha). Comparison of the two kinds of fish indicated that the latter have smaller hearts containing less total lipid. The most notable finding involved virtually complete loss, on average 94%, of heart triglycerides during the fresh water migration to the spawning grounds. In vivo palmitate-1-¹⁴C incorporation into heart triglycerides, as well as heart slice incubations, revealed the triglyceride pathway as an active metabolic route even in post-spawning fish that were only hours from death. The heart took up and retained fatty acid from the serum more readily than liver, skeletal muscle or brain. Following intravenous injection of the label, maximum specific activity of heart triglycerides was achieved in approximately one hour. The rapid turnover of the glyceride pool coupled with its diminishing mass is evidence of a substantial fatty acid flow through this intermediate in the heart muscle.     

The effect of starvation in the rat on metabolite concentrations in blood,liver and skeletal muscle

The effects of starvation on the concentration of blood and tissue metabolites was determined at different times in rats starved up to 6 days.The concentration of the hepatic gluconeogenic intermediates: pyruvate, phosphoenolpyruvate, 2-phosphoglycerate and 3-phosphoglycerate, decreased by 50% by the third day and then gradually increased to control levels by the sixth day of starvation. The change in the concentration of these metabolites correlates inversely with the plasma free fatty acid levels and the -hydroxybutyrate: acetoacetate (B/A) ratios, suggesting that the increased generation of reducing equivalents from free fatty acid oxidation stimulate glyceraldehyde-phosphate dehydrogenase. However, this apparent stimulation does not appear to control glyconeogenic flux. The concentration of hepatic oxaloacetate increased gradually during starvation and correlated closely with the increase in hepatic gluconeogenic flux suggesting that the hepatic concentration of oxaloacetate may be important in controlling the rate of hepatic gluconeogenesis.The calculated equilibrium expression: [alanine] [-ketoglutarate]/[pyruvate] [glutamate] and [aspartate] [-ketoglutarate]/[oxdaloacetate] [glutamate] for alanine aminotransferase and aspartate amino transferase respectively, remained fairly constant in all the tissues studied throughout the starvation period, despite large changes in the concentrations of the individual reactants, indicating that these reactions are near equilibrium.The -hydroxybutyrate: acetoacetate (B/A) ratios, taken to reflect the mitochondrial redox state, increased more than 4-fold in liver and muscle after the first day of starvation. It decreased after the third day of starvation and returned close to prefasting levels by the sixth day. The change in B/A ratios in blood was similar to those observed in the organs, except that the magnitude of the change was less. The changes observed in the mitochondrial redox state during starvation correlate closely with the changes in plasma free fatty acid concentrations and with the rate of fatty acid oxidation.     

The effects of 11-deoxycorticosterone and antidiuretic hormone (pitressin) on fluid exchange and electrolyte excretion by normal and starved polyuric-polydipsic rabbits

Summary The effects of 11-deoxycorticosterone (DOC) and antidiuretic hormone (pitressin) (ADH) on fluid exchange and Na⁺ excretion have been studied in normal rabbits and in rabbits showing a typical polyuric-polydipsic response to 4 days starvation. DOC (0.5 mg/kg body wt/day i.m. during 4 days starvation) significantly reduced total Na⁺ excretion to 48% (mean) of the level observed over 4 days starvation alone, while water intake and urine output volumes fell to 71% and 73% of their previous values respectively. ADH (0.1 units/kg body wt/day i.m. during 4 days starvation) caused water intake and urine output to fall to 55% and 44% of the levels observed during starvation alone, whithout significantly affecting Na⁺ output. These occurrences were correlated with the gradients of [Na⁺], [K]⁺, [urea] and hydration in renal tissue at the end of 4 day periods. Similar observations were made on groups of rabbits which failed to show a polyuric-polydipsic response. The findings are interprected in terms of metabolic, endocrine and physical factors likely to affect tubular function and Na⁺ output during starvation and polyuria-polydipsia.