The distribution and function of sympathetic innervation in skeletal muscle have largely remained elusive. Here we demonstrate that sympathetic neurons make close contact with neuromuscular junctions and form a network in skeletal muscle that may functionally couple different targets including blood vessels, motor neurons, and muscle fibers. Direct stimulation of sympathetic neurons led to activation of muscle postsynaptic β2-adrenoreceptor (ADRB2), cAMP production, and import of the transcriptional coactivator peroxisome proliferator-activated receptor γ-coactivator 1α (PPARGC1A) into myonuclei. Electrophysiological and morphological deficits of neuromuscular junctions upon sympathectomy and in myasthenic mice were rescued by sympathicomimetic treatment. In conclusion, this study identifies the neuromuscular junction as a target of the sympathetic nervous system and shows that sympathetic input is crucial for synapse maintenance and function

This study showed for the first time changes in the reproductive biology of Biomphalaria glabrata experimentally infected with Angiostrongylus cantonensis. The values of all the parameters analyzed (total number of eggs, number of egg masses, number of eggs/mass, number of eggs/snail, percentage of viable eggs and galactogen content in albumen gland) changed with progressive infection. The results indicate the occurrence of partial parasitic castration of B. glabrata by A. cantonensis larvae, probably in response to the depletion of energy reserves, with no injuries to the gonadal tissues.

Autonomic regulation processes in striated muscles are largely mediated by cAMP/PKA-signaling. In order to achieve specificity of signaling its spatial-temporal compartmentation plays a critical role. We discuss here how specificity of cAMP/PKA-signaling can be achieved in skeletal muscle by spatio-temporal compartmentation. While a microdomain containing PKA type I in the region of the neuromuscular junction (NMJ) is important for postsynaptic, activity-dependent stabilization of the nicotinic acetylcholine receptor (AChR), PKA type I and II microdomains in the sarcomeric part of skeletal muscle are likely to play different roles, including the regulation of muscle homeostasis. These microdomains are due to specific A-kinase anchoring proteins, like rapsyn and myospryn. Importantly, recent evidence indicates that compartmentation of the cAMP/PKA-dependent signaling pathway and pharmacological activation of cAMP production are aberrant in different skeletal muscles disorders. Thus, we discuss here their potential as targets for palliative treatment of certain forms of dystrophy and myasthenia. Under physiological conditions, the neuropeptide, α-calcitonin-related peptide, as well as catecholamines are the most-mentioned natural triggers for activating cAMP/PKA signaling in skeletal muscle. While the precise domains and functions of these first messengers are still under investigation, agonists of β2-adrenoceptors clearly exhibit anabolic activity under normal conditions and reduce protein degradation during atrophic periods. Past and recent studies suggest direct sympathetic innervation of skeletal muscle fibers. In summary, the organization and roles of cAMP-dependent signaling in skeletal muscle are increasingly understood, revealing crucial functions in processes like nerve-muscle interaction and muscle trophicity.

Although we have shown that catecholamines suppress the activity of the Ubiquitin‐Proteasome System (UPS) and atrophy‐related genes expression through a cAMP‐dependent manner in skeletal muscle from rodents, the underlying mechanisms remain unclear. Here, we report that a single injection of norepinephrine (NE; 1 mg kg−1; s.c) attenuated the fasting‐induced up‐regulation of FoxO‐target genes in tibialis anterior (TA) muscles by the stimulation of PKA/CREB and Akt/FoxO1 signaling pathways. In addition, muscle‐specific activation of PKA by the overexpression of PKA catalytic subunit (PKAcat) suppressed FoxO reporter activity induced by (1) a wild‐type; (2) a non‐phosphorylatable; (3) a non‐phosphorylatable and non‐acetylatable forms of FoxO1 and FoxO3; (4) downregulation of FoxO protein content, and probably by (5) PGC‐1α up‐regulation. Consistently, the overexpression of the PKAcat inhibitor (PKI) up‐regulated FoxO activity and the content of Atrogin‐1 and MuRF1, as well as induced muscle fiber atrophy, the latter effect being prevented by the overexpression of a dominant negative (d. n.) form of FoxO (d.n.FoxO). The sustained overexpression of PKAcat induced fiber‐type transition toward a smaller, slower, and more oxidative phenotype and improved muscle resistance to fatigue. Taken together, our data provide the first evidence that endogenous PKA activity is required to restrain the basal activity of FoxO and physiologically important to maintain skeletal muscle mass.

The influence of different photophases (0, 6, 12, 18 and 24 hours) on the triglycerides and total cholesterol contents in the hemolymph of A. fulica was evaluated, since there is no information in the literature about the influence of this factor on lipids metabolism in mollusks. After 2 and 4 weeks of exposure the snails were dissected. The cholesterol content at the 2 nd and 4 th weeks post exposure only varied significantly in the groups exposed at 24 hours and 0 hour of photophase, respectively. Probably, such increase may be a result of a rise in cholesterol biosynthesis and/or remodelling of cell membranes. There were no significant differences among the content of triglycerides in the snails exposed to 6, 12, 18 and 24 hours of photophase during two weeks. The snails exposed to intermediate photophase (6 and 12 hours) had the triglycerides content increased, ranging over values near to those observed in the group exposed to 0 hour. Results showed that triglycerides metabolism in A. fulica are more influenced by photoperiod than cholesterol metabolism. A negative relation is maintained between the triglycerides content in the hemolymph and the different photophases, with lower mobilisation of triglycerides under shorter photophases.Keywords: Achatina fulica, cholesterol, photoperiod, triglycerides, snail. Análises dos lipídeos no gigante africano Achatina fulica (Bowdich, 1822) expostos a diferentes fotoperíodos ResumoA influência de diferentes fotofases (0, 6, 12, 18 e 24 horas) sobre os conteúdos de triglicerídeos e de colesterol total na hemolinfa de A. fulica foi avaliada, uma vez que não há na literatura informações sobre a influência deste fator sobre o metabolismo de moluscos. Após 2 e 4 semanas de exposição, os moluscos foram dissecados. O conteúdo de colesterol até a 2 a e 4 a semanas pós exposição somente variou significativamente nos grupos expostos a 24 horas e 0 horas de fotofase, respectivamente. Provavelmente, tal aumento pode ser resultado de uma elevada biossíntese de colesterol e/ou remodelamento de membranas celulares. Não houve diferenças significativas entre o conteúdo de triglicerídeos nos moluscos expostos a 6, 12, 18 e 24 horas de fotofase até a segunda semana. Os moluscos expostos a fotofases intermediárias (6 e 12 horas) tiveram o conteúdo de triglicerídeos aumentados, levando seus valores próxi-mo àqueles observados para o grupo exposto a 0 hora de fotofase. Isto mostra que o metabolismo de triglicerídeos em A. fulica é mais influenciado pelo fotoperíodo do que o metabolismo de colesterol. Uma relação negativa é mantida entre o conteúdo de triglicerídeos na hemolinfa e as diferentes fotofases, com menor mobilização de triglicerídeos sob fotofases curtas.