RESUMO
The objective of this study was to evaluate the effects of caloric restriction (CR) on myenteric neurons in the duodenum of Wistar rats during aging. Thirty rats were divided into three groups: the C group (six-month-old animals that were fed a normal diet from weaning until six months of age), the SR group (18-month-old animals that were fed a normal diet from weaning until 18 months of age) and the CR group (18-month-old animals that were fed a 30% CR diet after six months of age). After 12 months, the animals were euthanized. Whole-mount preparations of the duodenums were either stained with Giemsa or underwent NADPH-diaphorase histochemistry to determine the general myenteric neuron population and the nitrergic neuron subpopulation (NADPH-d+), respectively. The NADPH-d-negative (NADPH-d-) neuron population was estimated based on the difference between the Giemsa-stained and NADPH-d+ neurons. The neurons were counted, and the cell body areas were measured. Aging was associated with neuronal loss in the SR group, which was minimized by caloric restriction in the CR group. The density (mm(2)) of the Giemsa-stained neurons was higher in the SR group (79.09 ± 6.25) than in the CR (92.37 ± 11.6) and C (111.68 ± 15.26) groups. The density of the NADPH-d+ neurons was higher in the SR group (44.90 ± 5.88) than in the C (35.75 ± 1.6) and RC (39.14 ± 7.02) groups. The density of NADPH-d- neurons was higher in the CR (49.73 ± 12.08) and C (75.64 ± 17.05) groups than in the SR group (33.82 ± 4.5). In the C group, 32% and 68% of the Giemsa-stained myenteric neurons were NADPH-d+ or NADPH-d-, respectively. With aging (SR group), the percentage of nitrergic neurons (56.77%) increased, whereas the percentage of NADPH-d- neurons (43.22%) decreased. In the CR group, the change in the percentage of nitrergic (42.37%) and NADPH-d- (57.62%) neurons was lower. As NADPH-d- neurons will be mostly cholinergic neurons, CR appears to reduce the loss of cholinergic neurons during aging. The cell body dimensions (µm(2)) were not altered by aging or CR. Thus, CR had a protective effect on myenteric neurons during aging.
Assuntos
Restrição Calórica , Duodeno/crescimento & desenvolvimento , Duodeno/inervação , Plexo Mientérico/fisiologia , Plasticidade Neuronal/fisiologia , Envelhecimento/fisiologia , Animais , Corantes Azur , Contagem de Células , Tamanho Celular , Dieta , Duodeno/fisiologia , Gânglios Autônomos/citologia , Gânglios Parassimpáticos/citologia , Gânglios Parassimpáticos/crescimento & desenvolvimento , Imuno-Histoquímica , Masculino , NADPH Desidrogenase/metabolismo , Neurônios/enzimologia , Neurônios/fisiologia , Neurônios/ultraestrutura , Ratos , Ratos WistarRESUMO
Acetylcholine and ATP appear to mediate excitatory transmission between receptor (glomus) cells and the petrosal ganglion (PG) neuron terminals in the carotid body. In most species these putative transmitters are excitatory, while inhibitory effects had been reported in the rabbit. We studied the effects of the application of acetylcholine and ATP to the PG on the carotid nerve activity in vitro. Acetylcholine and ATP applied to the PG increased the carotid nerve activity in a dose-dependent manner. Acetylcholine-induced responses were mimicked by nicotine, antagonized by hexamethonium, and enhanced by atropine. Bethanechol had no effect on basal activity, but reduced acetylcholine-induced responses. Suramin antagonized ATP-induced responses, and AMP had little effect on the carotid nerve activity. Our results suggest that rabbit PG neurons projecting through the carotid nerve are endowed with nicotinic acetylcholine and purinergic P2 receptors that increase the carotid nerve activity, while simultaneous activation of muscarinic cholinergic receptors reduce the maximal response evoked by nicotinic cholinergic receptor activation.
Assuntos
Acetilcolina/farmacologia , Trifosfato de Adenosina/farmacologia , Gânglios Parassimpáticos/fisiologia , Potenciais de Ação/efeitos dos fármacos , Animais , Atropina/farmacologia , Betanecol/farmacologia , Corpo Carotídeo/efeitos dos fármacos , Corpo Carotídeo/fisiologia , Relação Dose-Resposta a Droga , Estimulação Elétrica , Eletrofisiologia , Gânglios Parassimpáticos/citologia , Gânglios Parassimpáticos/efeitos dos fármacos , Hexametônio/farmacologia , Masculino , Agonistas Muscarínicos/farmacologia , Antagonistas Muscarínicos/farmacologia , Neurônios Aferentes/efeitos dos fármacos , Nicotina/farmacologia , Agonistas Nicotínicos/farmacologia , Antagonistas Nicotínicos/farmacologia , CoelhosRESUMO
The Edinger-Westphal nucleus (EWN) is a central preganglionic parasympathetic cell group that gives rise to cholinergic input to the ciliary ganglion, thereby regulating several neurovegetative ocular functions. Recently, the supposed presence of the neuropeptide urocortin (UCN) has been reported in EWN neurons in rodent brain. The purpose of the present study was to examine the distribution of UCN in avian brain and to investigate by immunohistochemical analysis the possible use of this substance as an EWN marker in a non-mammalian class of vertebrates. Brain tissue of pigeons was incubated with a specific antibody against UCN and the results showed labeling of many small neurons, forming a double wing in the dorsal mesodiencephalic transition area. Their size and shape, however, differed from those of EWN neurons, and they were preferentially located rostral to the EWN. Double-label experiments employing an antibody against the enzyme choline acetyltransferase (ChAT) showed that UCN is not localized to the cholinergic cells of the EWN and confirmed the rostral distributionof UCN never overlapping the ChAT+ EWN cells. Taken together, these results suggest that, at least in pigeons, the UCN+ population does not belong to the traditionally defined EWN.
Assuntos
Columbidae , Hormônio Liberador da Corticotropina/análise , Gânglios Parassimpáticos/química , Neurônios/química , Nervo Oculomotor/química , Animais , Fibras Autônomas Pré-Ganglionares/química , Gânglios Parassimpáticos/citologia , Imuno-Histoquímica , Nervo Oculomotor/citologia , UrocortinasRESUMO
The present work deals with the finding and characterization of a neurotrophic factor present in serum-free Dulbecco's modified Eagle's medium in which rat sciatic nerves previously cultured for 9 days were maintained for 24 h. This sciatic nerve conditioned medium (SNCM) produced neuronal differentiation and neurite outgrowth on PC12 cells, as well as survival and differentiation of eight-day old chick embryo dorsal root ganglion (E8-DRG) and ciliary ganglion (E8-CG) neurons. SNCM activity was decreased by dilution, heating and trypsin treatment; it was not inhibited by anti-NGF and anti-bFGF antibodies; and it was not mimicked by CNTF, laminin and fibronectin. By utilizing its neurite-promoting activity on PC12 cells, experiments oriented to purify the factor were carried out. Ultrafiltration, heparin-affinity chromatography and size-exclusion high pressure liquid chromatography (HPLC) were employed. The ability of SNCM to induce PC12 cell, E8-DRG and E8-CG neuronal differentiation, the heparin affinity of the active SNCM protein, and the size-exclusion HPLC elution characteristics of the active protein suggest that the active component of the SNCM is, in all probability, a novel sciatic nerve neurotrophic factor (SNTF).
Assuntos
Gânglios Parassimpáticos/citologia , Gânglios Espinais/citologia , Fatores de Crescimento Neural/farmacologia , Neurônios/citologia , Nervo Isquiático/fisiologia , Animais , Diferenciação Celular/fisiologia , Sobrevivência Celular/efeitos dos fármacos , Embrião de Galinha , Cromatografia de Afinidade , Cromatografia Líquida de Alta Pressão , Meios de Cultivo Condicionados , Meios de Cultura Livres de Soro , Feminino , Gânglios Parassimpáticos/embriologia , Gânglios Espinais/embriologia , Masculino , Células PC12 , Ratos , Tripsina , UltrafiltraçãoRESUMO
Determinaçoes morfométricas estereológicas foram feitas em microscopia óptica de cortes semifinos de gânglio pterigopalatino (GP) do rato. Os seguintes parâmetros do pericário foram analisados: diâmetro equatorial (D), densidade volumétrica (Vv), densidade da superfície por volume (Sv) e densidade numérica (Nv). Os resultados obtidos do estudo de três animais, foram (média + desvio padrao): D = 23,93 + 6,46 mum; Vv = 53,83 + 7,40 por cento; Sv = 0,173 + 0,026 mum1; Nv (x 10(-5)) = 5,38 + 1,26 mum(-3). Os gânglios parassimpáticos cranianos apresentam variaçoes na mesma espécie, e entre diferentes espécies, quanto ao Nv e o tamanho das células.
Assuntos
Animais , Masculino , Ratos , Gânglios Parassimpáticos/citologia , Ratos WistarRESUMO
Quantifications in parasympathetic ganglia are not available in literature. The otic ganglia of 9 Wistar rats were studied (thick and semi-thin sections) in order to determine the following quantitative data: ganglionic volume (GV), neuronal volume density (Vv), neuronal cellular surface per cell volume (Sv), and neuronal numerical density (Nv). The results showed (mean +/- SD): GV = 0.31 +/- 0.05 mm3, Vv = 39.62 +/- 12.25%, Sv = 0.169 +/- 0.056 microns-1 and Nv = 3.84 x 10(-5) +/- 1.69 x 10(-5) microns-3. These determinations provide a basis for comparisons of parasympathetic with sympathetic ganglia.