Chronic treatment with dexamethasone alters clock gene expression and melatonin synthesis in rat pineal gland at night.

BACKGROUND: Melatonin is a neuroendocrine hormone that regulates many functions involving energy metabolism and behavior in mammals throughout the light/dark cycle. It is considered an output signal of the central circadian clock, located in the suprachiasmatic nucleus of the hypothalamus. Melatonin synthesis can be influenced by other hormones, such as insulin and glucocorticoids in pathological conditions or during stress. Furthermore, glucocorticoids appear to modulate circadian clock genes in peripheral tissues and are associated with the onset of metabolic diseases. In the pineal gland, the modulation of melatonin synthesis by clock genes has already been demonstrated. However, few studies have shown the effects of glucocorticoids on clock genes expression in the pineal gland. RESULTS: We verified that rats treated with dexamethasone (2 mg/kg body weight, intraperitoneal) for 10 consecutive days, showed hyperglycemia and pronounced hyperinsulinemia during the dark phase. Insulin sensitivity, glucose tolerance, melatonin synthesis, and enzymatic activity of arylalkylamine N-acetyltransferase, the key enzyme of melatonin synthesis, were reduced. Furthermore, we observed an increase in the expression of Bmal1, Per1, Per2, Cry1, and Cry2 in pineal glands of rats treated with dexamethasone. CONCLUSION: These results show that chronic treatment with dexamethasone can modulate both melatonin synthesis and circadian clock expression during the dark phase.

Resistance training controls arterial blood pressure in rats with L-NAME- induced hypertension.

BACKGROUND: Arterial hypertension is a multifactorial chronic condition caused by either congenital or acquired factors. OBJECTIVE: To evaluate the effects of Resistance Training (RT) on arterial pressure, and on vascular reactivity and morphology, of L-NAME-treated hypertensive rats. METHODS: Male Wistar rats (200 - 250 g) were allocated into Sedentary Normotensive (SN), Sedentary Hypertensive (SH) and Trained Hypertensive (TH) groups. Hypertension was induced by adding L-NAME (40 mg/Kg) to the drinking water for four weeks. Arterial pressure was evaluated before and after RT. RT was performed using 50% of 1RM, 3 sets of 10 repetitions, 3 times per week for four weeks. Vascular reactivity was measured in rat mesenteric artery rings by concentration-response curves to sodium nitroprusside (SNP); phenylephrine (PHE) was also used for histological and stereological analysis. RESULTS: Resistance training inhibited the increase in mean and diastolic arterial pressures. Significant reduction was observed in Rmax (maximal response) and pD2 (potency) of PHE between SH and TH groups. Arteries demonstrated normal intima, media and adventitia layers in all groups. Stereological analysis demonstrated no significant difference in luminal, tunica media, and total areas of arteries in the SH and TH groups when compared to the SN group. Wall-to-lumen ratio of SH arteries was significantly different compared to SN arteries (p<0.05) but there was no difference when compared to TH arteries. CONCLUSIONS: RT was able to prevent an increase in blood pressure under the conditions in this study. This appears to involve a vasoconstrictor regulation mechanism and maintenance of luminal diameter in L-NAME induced hypertensive rats.

Treinamento resistido controla a pressão arterial de ratos hipertensos induzidos por l-NAME / Resistance training controls arterial blood pressure in rats with L-NAME- induced hypertension

FUNDAMENTO: A hipertensão arterial é uma síndrome multifatorial, crônica, causada tanto por fatores congênitos ou adquiridos. OBJETIVO: Avaliar os efeitos do treinamento físico resistido (TR) sobre pressão arterial, reatividade e morfologia vascular de ratos hipertensos induzidos por L-NAME. MÉTODOS: Ratos Wistar machos (200-250 g) foram divididos em 3 grupos: normotenso sedentário (NS), hipertenso sedentário (HS) e hipertenso treinado (HT). A hipertensão foi induzida pela administração de L-NAME (40 mg/kg) na água de beber por 4 semanas. A pressão arterial foi avaliada antes e após o TR. O TR foi realizado utilizando 50% de 1RM, em 3 séries de 10 repetições, 3 vezes por semana, durante quatro semanas. A reatividade vascular foi mensurada em artéria mesentérica superior por curvas concentração resposta ao nitroprussiato de sódio (NPS) e fenilefrina (FEN). Além disso, foram realizadas análises histológicas e estereológicas. RESULTADOS: O TR inibiu o aumento das pressões arteriais média e diastólica. Foi observada uma redução significativa na resposta máxima e na potência da FEN entre os grupos HS e HT. A análise histológica evidenciou aspecto normal para as túnicas íntima, média e adventícia em todos os grupos. Não houve diferença significativa nas áreas do lúmen, da túnica média e total das artérias dos grupos HS e HT em relação ao NS. A razão parede/lúmen arterial do grupo HS apresentou diferença significativa em relação ao NS (p < 0,05), mas esta não foi diferente do HT. CONCLUSÕES: O TR foi capaz de prevenir a elevação da pressão arterial sob as condições deste estudo. Este controle parece envolver a regulação de mecanismo vasoconstritor e a manutenção do diâmetro luminal de ratos hipertensos induzidos por L-NAME.

BACKGROUND: Arterial hypertension is a multifactorial chronic condition caused by either congenital or acquired factors. OBJECTIVE: To evaluate the effects of Resistance Training (RT) on arterial pressure, and on vascular reactivity and morphology, of L-NAME-treated hypertensive rats. METHODS: Male Wistar rats (200 - 250 g) were allocated into Sedentary Normotensive (SN), Sedentary Hypertensive (SH) and Trained Hypertensive (TH) groups. Hypertension was induced by adding L-NAME (40 mg/Kg) to the drinking water for four weeks. Arterial pressure was evaluated before and after RT. RT was performed using 50% of 1RM, 3 sets of 10 repetitions, 3 times per week for four weeks. Vascular reactivity was measured in rat mesenteric artery rings by concentration-response curves to sodium nitroprusside (SNP); phenylephrine (PHE) was also used for histological and stereological analysis. RESULTS: Resistance training inhibited the increase in mean and diastolic arterial pressures. Significant reduction was observed in Rmax (maximal response) and pD2 (potency) of PHE between SH and TH groups. Arteries demonstrated normal intima, media and adventitia layers in all groups. Stereological analysis demonstrated no significant difference in luminal, tunica media, and total areas of arteries in the SH and TH groups when compared to the SN group. Wall-to-lumen ratio of SH arteries was significantly different compared to SN arteries (p<0.05) but there was no difference when compared to TH arteries. CONCLUSIONS: RT was able to prevent an increase in blood pressure under the conditions in this study. This appears to involve a vasoconstrictor regulation mechanism and maintenance of luminal diameter in L-NAME induced hypertensive rats.

Ultrastructural aspects of lingual papillae in squirrel monkey (Saimiri sciureus).

Saimiri sciureus is one of the smallest Cebidae native of Amazon region and also found at the biological reserve of northeast Atlantic forest. It is an omnivore animal, with diversified diet that directly influences the lingual mucosa, which includes certain types of papillae with different organization levels. The present study attempted to describe the morphological and ultrastructure aspects of the dorsal surface of the S. sciureus. Five tongues of de S. sciureus were analyzed from three males and two females who died from natural causes and were obtained from breeding colonies of CENP-Ananindeua-PA. Main macroscopic features were a general triangular shape with a craniocaudal elongation pointed apex. Tissue samples--apex, body, and root of tongue--were fixed in modified Karnovsky solution, following standard scanning protocol, mounted in stubs, coated by gold, and analyzed by Scanning Electron Macroscopy (SEM). Four types of papillae were described: filiform (along all tissue extension with 154 µm of diameter), fungiform (along all tissue extension with 272 µm of diameter), vallate [just three units in caudal (dorsal) portion with 830 µm of diameter] and foliate (one pair at caudolateral surface with ∼ 13 projections and 3000 µm in length). Data analysis indicates that the distribution and ultra structural morphology of the S. sciureus lingual papillae are some similar to other primates.

Macro- and microstructure of the superior cervical ganglion in dogs, cats and horses during maturation.

The superior cervical ganglion (SCG) provides sympathetic input to the head and neck, its relation with mandible, submandibular glands, eyes (second and third order control) and pineal gland being demonstrated in laboratory animals. In addition, the SCG's role in some neuropathies can be clearly seen in Horner's syndrome. In spite of several studies published involving rats and mice, there is little morphological descriptive and comparative data of SCG from large mammals. Thus, we investigated the SCG's macro- and microstructural organization in medium (dogs and cats) and large animals (horses) during a very specific period of the post-natal development, namely maturation (from young to adults). The SCG of dogs, cats and horses were spindle shaped and located deeply into the bifurcation of the common carotid artery, close to the distal vagus ganglion and more related to the internal carotid artery in dogs and horses, and to the occipital artery in cats. As to macromorphometrical data, that is ganglion length, there was a 23.6% increase from young to adult dogs, a 1.8% increase from young to adult cats and finally a 34% increase from young to adult horses. Histologically, the SCG's microstructure was quite similar between young and adult animals and among the 3 species. The SCG was divided into distinct compartments (ganglion units) by capsular septa of connective tissue. Inside each ganglion unit the most prominent cellular elements were ganglion neurons, glial cells and small intensely fluorescent cells, comprising the ganglion's morphological triad. Given this morphological arrangement, that is a summation of all ganglion units, SCG from dogs, cats and horses are better characterized as a ganglion complex rather than following the classical ganglion concept. During maturation (from young to adults) there was a 32.7% increase in the SCG's connective capsule in dogs, a 25.8% increase in cats and a 33.2% increase in horses. There was an age-related increase in the neuronal profile size in the SCG from young to adult animals, that is a 1.6-fold, 1.9-fold and 1.6-fold increase in dogs, cats and horses, respectively. On the other hand, there was an age-related decrease in the nuclear profile size of SCG neurons from young to adult animals (0.9-fold, 0.7-fold and 0.8-fold in dogs, cats and horses, respectively). Ganglion connective capsule is composed of 2 or 3 layers of collagen fibres in juxtaposition and, as observed in light microscopy and independently of the animal's age, ganglion neurons were organised in ganglionic units containing the same morphological triad seen in light microscopy.

Estudo morfométrico e estereológico do gânglio celíaco em cães sadios / Morphometric and stereological study of the celiac ganglia in healthy dogs

Nesta pesquisa o aspecto macroestrutural, microestrutural e histoquímico foram investigados em 6 cães clinicamente saudáveis para identificar a possível alteração na estrutura, morfométrica e parâmetros quantitativos de neurônios do complexo ganglionar celíaco. Nossa observação revela que o gânglio celíaco foi originado da origem da artéria celíaca e mostra um aspecto irregular sendo caracterizado como um complexo. Histoquimicamente, neurônios NADPH diaforase reativos foram identificados. Esta reação positiva, em animais saudáveis, permite-nos concluir que estes neurônios eram potencialmente nitrergicos, contudo, para confirmar o aspecto nitrergico para estes neurônios ele é necessário combinar métodos imunohistoquimicos.

In this research, the macrostructural, microstructural and histochemical aspects were Investigated in 6 clinacally health dogs to identify the possible alterations on the structure, morphometric and qualitative parameteres of neurons of the celiac ganglionar complex. Our observations revealed that the celiac ganglion was originated dose to the origin of the celiac artery and showed a irregular aspect, being caractherized as a complex. Histochemical/y, neurons NADPH diaphorase reactives were identified. This positive reaction, on health animais, led us to conclude this neurons were potentially nitrergic, besides, to confirm the nitrergic aspect for this neurons it isnecessary to combine immunohistochemical method.

Macrostructure of the cranial cervical ganglionar complex and distal vagal ganglion during post natal development in dogs

Doze cães domésticos (Canis familiaris) foram dissecados para o estudo da situação, arranjo e ramificação nervosa do gânglio distal do nervo vago e gânglio cervical cranial. Os gânglios apresentaram-se fusiformes e recobertos pelo músuculo digástrico. Os principais ramos do gânglio cervical cranial observados foram os ramos para a artéria carótida externa e artéria carótida interna. Destacou-se o nervo laringeal cranial como ramo do gânglio distal do nervo vago. O estudo revelou gânglio cervical cranial e o gânglio distal do vago eram estruturas bem desenvolvidas e não encontrou-se diferenças anatômicas entre os gânglios observados em ambos antímeros.