Low energy reserves are associated with fasting susceptibility in Neotropical nectar bats Glossophaga soricina / Baixas reservas energéticas corporais estão associadas à susceptibilidade ao jejum da espécie Glossophaga soricina

Abstract Neotropical nectar-feeding bats consume large amounts of sugar and use most of their energy-rich diet directly from the bloodstream, suggesting an adaptation towards lower body energy reserves. Here we tested the hypothesis that bats Glossophaga soricina spare the energy costs of storing energy reserves, even if this would represent a risky susceptibility during fasting. Blood glucose concentrations in 18 h fasted bats showed a 40% decrease. Breast muscle and adipose tissue lipids, as well as carcass fatty acids and liver glycogen, were also decreased following fasting. The inability to keep normoglycemia following a short-term fasting (i.e. 28 h) confirm that nectar bats invest little on storing energy reserves and show a severe fasting susceptibility associated to this pattern. Our study also support the general hypothesis that evolutionary specializations towards nectar diets involve adaptations to allow a decreased body mass, which reduces the energy costs of flight while increases foraging time.

Resumo Morcegos nectarívoros que ocorrem na região Neotropical consomem grandes quantidades de carboidratos, e usam a energia obtida da dieta diretamente, a partir da glicose na circulação sanguínea. Esta adaptação sugere que morcegos nectarívoros tenham evoluído no sentido de apresentar adaptações fisiológicas que permitam o baixo armazenamento de reservas energéticas corporais. Nós testamos a hipótese de que morcegos Glossophaga soricina poupam o gasto energético envolvido com a formação de reservas energéticas teciduais, mesmo que isso represente uma arriscada suscetibilidade da espécie frente ao jejum. As concentrações de glicose apresentaram uma diminuição de 40% após 18 h de jejum. As concentrações de lipídios do músculo peitoral e do tecido adiposo, bem como as de ácidos graxos da carcaça e glicogênio hepático também diminuíram após 18 h de jejum. A incapacidade de manter a normoglicemia observada após o jejum de curto-prazo confirma que morcegos nectarívoros desta espécie não investem na formação de reservas energéticas, e apresentam, consequentemente, uma severa susceptibilidade ao jejum. Este estudo suporta a hipótese de que adaptações evolucionárias da espécie envolvem diminuição da massa corporal, reduzindo o custo energético do voo e aumentado o tempo de forrageamento.

Valores hematológicos de bugios pretos (Alouatta caraya) de vida livre da região do Alto Rio Paraná, sul do Brasil / Hematologic values of free-ranging black-and-gold howlers monkeys (Alouatta caraya) from the region of Upper Paraná River, Southern Brazil

Descreveram-se os valores hematológicos de bugios pretos (Alouatta caraya) e estabeleceram-se diferenças entre sexo e idade, de 36 animais aparentemente saudáveis, de vida livre da região do Alto Rio Paraná, sul do Brasil. Os animais foram capturados e contidos quimicamente com cloridrato de tiletamina e cloridrato de zolazepam, na dose média de 5,5mg/kg, por via intramuscular. Na comparação entre os sexos, houve diferença para número de hemácias (4,48±1,36 e 3,58±0,91 x10(6)/mm³), maior nas fêmeas, e volume globular médio (90,99±27,65 e 118,36±44,63fL) e número de eosinófilos (0,30±0,24 e 0,76±0,85 x10³/mm³), maior nos machos. O volume globular (39,46±3,53 e 36,69±3,54 por cento) e a proteína total plasmática (7,91±0,53 e 7,40±0,63g/dL) foram significativamente mais baixos nos animais jovens.

The hematologic values and the influence of gender and age were described in 36 free-ranging healthy black-and-gold howler monkeys (Alouatta caraya) from the region of Paraná river, Southern Brazil. The animals were caught with trap models and intramuscularly anesthetized with 5.5mg/kg tilitamine/zolazepam hydrochlorides. The red blood cells were higher in females (4.48±1,36 vs. 3.58±0.91x10(6)/mm³) while mean corpuscular volume (90.99±27.65 and 118.36±44.63 fL) and eosinophils (0.30±0.24 and 0.76±0.85x10³/mm³) were significant higher in males. The packed cell volume (39.46±3.53 and 36.69±3.54 percent) and plasma total protein (7.91±0.53 and 7.40±0.63g/dL) were lower in juveniles.

Effects of chronic ethanol treatment on monoamine levels in rat hippocampus and striatum

We studied the effects of ethanol on concentrations of noradrenaline (NE), dopamine (DA) and serotonin (5-HT) and their metabolites in rat hippocampus and striatum. Ethanol (2 or 4 g/kg, po, from a 20 percent aqueous solution) was administered daily to male Wistar rats (4-13 per group) for 30 days and animals were sacrificed 30 min or 48 h after the last administration. Monoamines were measured by HPLC and considered significant at P < 0.05. A 47 percent increase in 5-HT levels was observed in the hippocampus with 4 g/kg ethanol in the 30-min protocol. Ethanol (2 and 4 g/kg) decreased DA (2114.5 ± 126.4 and 1785.1 ± 234.2 ng/g wet tissue, respectively) and 3,4-dihydroxyphenylacetic acid (DOPAC, 1477.6 ± 132.1 and 1218.8 ± 271.7 ng/g wet tissue, respectively) levels, while the higher dose also decreased NE (159.8 ± 13.5), 5-HT (228.0 ± 46.8) and 5-hydroxy-3-indoleacetic acid (5-HIAA, 304.4 ± 37.2 ng/g wet tissue), in the striatum after a 48-h withdrawal as compared to controls (DA: 3063.9 ± 321.3; DOPAC: 2379.6 ± 256.0; NE: 292.8 ± 50.2; 5-HT: 412.4 ± 36.2; 5-HIAA: 703.9 ± 61.4 ng/g wet tissue). In the 30-min protocol, ethanol (2 or 4 g/kg) decreased striatal NE (66 and 70 percent) and DA (50 and 36 percent) levels. On the other hand, increases were seen in 5-HIAA (146 and 153 percent) and 5-HT (59 and 86 percent) levels. Ethanol (2 g/kg, po) increased the homovanillic acid (HVA)/DA ratio (129 percent) in the striatum in the 30-min protocol, while at the higher dose it increased the HVA/DA ratio in the 48-h protocol (61 percent). These results indicate alterations in monoamines, mainly in the striatum, after chronic ethanol, which are influenced by dose and by the length of time after the last drug administration.