RESUMO
Sea anemones have a structurally simple nervous system that controls behaviors like feeding, locomotion, aggression, and defense. Specific chemical and tactile stimuli are transduced by ectodermal sensory cells and transmitted via a neural network to cnidocytes and epithelio-muscular cells, but the nature of the neurotransmitters operating in these processes is still under discussion. Previous studies demonstrated an important role of peptidergic transmission in cnidarians, but during the last decade the contribution of conventional neurotransmitters became increasingly evident. Here, we used immunohistochemistry on light and electron microscopical preparations to investigate the localization of glutamate and GABA in tentacle cross-sections of the sea anemone Phymactis papillosa. Our results demonstrate strong glutamate immunoreactivity in the nerve plexus, while GABA labeling was most prominent in the underlying epithelio-muscular layer. Immunoreactivity for both molecules was also found in glandular epithelial cells, and putative sensory cells were GABA positive. Under electron microscopy, both glutamate and GABA immunogold labeling was found in putative neural processes within the neural plexus. These data support a function of glutamate and GABA as signaling molecules in the nervous system of sea anemones.
Assuntos
Estruturas Animais/metabolismo , Ácido Glutâmico/imunologia , Anêmonas-do-Mar/anatomia & histologia , Anêmonas-do-Mar/metabolismo , Ácido gama-Aminobutírico/imunologia , Estruturas Animais/anatomia & histologia , Estruturas Animais/citologia , Estruturas Animais/ultraestrutura , Animais , Imuno-Histoquímica , Anêmonas-do-Mar/citologia , Anêmonas-do-Mar/ultraestruturaRESUMO
The immune, endocrine and nervous systems are closely interrelated, which allows the organism to respond to different types of stress such as infection. Chronic infectious and inflammatory conditions are often accompanied by an impaired reproductive function. Leptin, a hormone produced by adipose tissue, exerts a regulatory function on the reproductive axis. It has homology with other proinflammatory cytokines and could be modified by lipopolysaccharide (LPS). Therefore, these studies were designed to investigate the effect of LPS administration on the neuroendocrine mechanisms involved in the regulation of the reproductive axis during sexual maturation. Fifteen- and 30-day-old female rats were injected with a single dose of LPS 250 microg/kg (i.p.) and then nitric oxide synthase (NOS) activity, hypothalamic excitatory/inhibitory amino acids and Gn-RH content, serum LH and leptin concentration were studied. In 15-day-old female rats LPS treatment did not modify hypothalamic inducible (iNOS) and constitutive (cNOS) NOS activity, Gn-RH, glutamate (GLU) and GABA content. Also serum LH and leptin levels were not modified. In 30-day-old rats LPS increased iNOS and cNOS activity (p < 0.001) and hypothalamic Gn-RH content (p < 0.001). At this age hypothalamic GABA content was significantly decreased (p < 0.001) without changes in GLU content, and serum LH (p < 0.001) and leptin (p < 0.0001) decreased significantly. In summary, current studies have demonstrated that LPS administration to 15- and 30-day-old female rats results in a different response of the hypothalamus-pituitary-gonadal axis and of the adipose tissue, demonstrating an ontogenic response of the immune-neuroendocrine system to LPS administration.
Assuntos
Infecções Bacterianas/imunologia , Leptina/imunologia , Neuroimunomodulação/imunologia , Sistemas Neurossecretores/imunologia , Reprodução/imunologia , Maturidade Sexual/imunologia , Tecido Adiposo/imunologia , Tecido Adiposo/metabolismo , Envelhecimento/imunologia , Envelhecimento/metabolismo , Animais , Feminino , Ácido Glutâmico/imunologia , Ácido Glutâmico/metabolismo , Hormônio Liberador de Gonadotropina/imunologia , Hormônio Liberador de Gonadotropina/metabolismo , Sistema Hipotálamo-Hipofisário/imunologia , Sistema Hipotálamo-Hipofisário/metabolismo , Hipotálamo/imunologia , Hipotálamo/metabolismo , Mediadores da Inflamação/farmacologia , Leptina/sangue , Lipopolissacarídeos/farmacologia , Hormônio Luteinizante/sangue , Hormônio Luteinizante/imunologia , Sistemas Neurossecretores/metabolismo , Sistemas Neurossecretores/fisiopatologia , Óxido Nítrico Sintase/imunologia , Óxido Nítrico Sintase/metabolismo , Ratos , Ratos Wistar , Estresse Fisiológico/imunologia , Estresse Fisiológico/metabolismo , Estresse Fisiológico/fisiopatologia , Regulação para Cima/imunologia , Ácido gama-Aminobutírico/imunologia , Ácido gama-Aminobutírico/metabolismoRESUMO
Using immunohistochemistry and optical densitometry, somatostatin (SOM), calcitonin gene-related peptide (CGRP), and gamma-aminobutyric acid (GABA) were investigated in the lumbosacral spinal cord of the frog Rana catesbeiana after sciatic nerve transection. In control animals, the densest network of the SOM-, CGRP- and GABA-like immunoreactive fibers was located in the dorsal part of the lateral funiculus. SOM and GABA-like fibers were found in the dorsal terminal field and in the mediolateral band. The latter region showed CGRP and SOM-like immunoreactive cell bodies. SOM- and GABA-like immunoreactive neurons also occurred around the cavity of the central canal, and other GABA-like fibers were found in the ventral terminal field. While the ventral horn showed scarce somatostatin-like fibers, the putative motoneurons were immunoreactive for the two peptides investigated and GABA, but only a few SOM- and GABA-like fibers occurred in the ventral funiculus. After axotomy, GABA-like immunoreactivity decreased in the dorsal part of the lateral funiculus on the same side of the lesion. The other regions remained labeled. These changes were observed at 3 days following axonal injury and persisted at 5, 8 and 15 days. There was no significant difference in the pattern of CGRP- and SOM- immunoreactivity between the axotomized and the control sides. These results are discussed in relation to the effects of the peripheral axotomy on GABA, SOM, and CGRP expression in vertebrates, emphasizing the use of frogs as a model to study the effects of peripheral nerve injury.