Histological study of the dynamics in epidermis regeneration of the carp tail fin (Cyprinus carpio, Linnaeus, 1758) / Estudo histológico da dinâmica da regeneração da epiderme da nadadeira caudal da carpa (Cyprinus carpio Linnaeus, 1758)

Teleostean fins when partially amputated suffer a regenerative process called epimorphic regeneration, characterized by the following stages: healing, based on the formation of a multistratified epidermal layer, the formation of a mass of pluripotent cells known as blastema, the differentiation of these cells, the synthesis and disposition of the extracellular matrix, morphological growth and restoration. The epidermis has a fundamental role in the regenerative process of fish fins, as the healing time of this structure leads it to a faster regenerative process and it also works as a defense against the external environment. In this sense, due to the fast regeneration shown by the epidermis, the aim of this paper is to study the histology of the regenerative dynamics of the carp fin tail (Cyprinus carpio), under the light and transmission electron microscope. Epidermic regeneration begins right in the first hours after the fin amputation and it continues throughout the regenerative process. After 24 hours, an apical epidermal cap is established. Cytoplasmatic prolongations and intercellular junctions are observed and the cells of the basal layer of the epidermis change from the cubic form to the cylindrical, due to the development of the cytoplasmatic organelles responsible for the synthesis of the basal membrane, lost after amputation. These results show the importance of histological studies in regenerative processes. We believe that the association of molecular biology with histological studies can throw further light onto these regenerative dynamics.

As nadadeiras dos teleósteos, quando parcialmente amputadas, sofrem um processo de regeneração chamado de regeneração epimórfica, caracterizado pelas seguintes fases: cicatrização, a partir da formação de uma capa epidermal multiestratificada, formação de uma massa de células mesenquimais multipotentes chamada blastema, diferenciação dessas células, síntese e deposição de matriz extracelular, crescimento e restauração morfológica. A epiderme tem papel fundamental no processo regenerativo das nadadeiras dos peixes, uma vez que a velocidade de cicatrização dessa estrutura leva a um processo regenerativo mais rápido e, também, age como uma defesa contra o ambiente externo. Assim, devido à rápida regeneração que a epiderme apresenta, tivemos como objetivo, neste trabalho, estudar a histologia da dinâmica regenerativa da epiderme das nadadeiras caudais da carpa (Cyprinus carpio) ao microscópio de luz e eletrônico de transmissão. A regeneração da epiderme tem início já nas primeiras horas após a amputação das nadadeiras e continua durante todo o processo regenerativo. Após 24 horas, uma capa epidermal apical é estabelecida. Prolongamentos citoplasmáticos e junções intercelulares são observados e as células da camada basal da epiderme passam da forma cúbica para a cilíndrica, devido ao desenvolvimento das organelas citoplasmáticas responsáveis pela síntese da membrana basal perdida após a amputação da nadadeira. Estes resultados mostram a importância de estudos histológicos em processos regenerativos. Acreditamos que a associação da biologia molecular a estes estudos histológicos poderá elucidar ainda melhor esta dinâmica regenerativa.

The regeneration of the tail fin actinotrichia of carp (Cyprinus carpio, Linnaeus, 1758) under the action of naproxen / A regeneração das actinotriquias da nadadeira caudal da carpa (Cyprinus carpio, Linnaeus, 1758) sob a ação do naproxeno

A conglomerate of small, rigid, fusiform spicules known as actinotrichia sustains the edge of tail fins of teleost. After amputation, these structures show an extremely fast regenerative capacity. In this study we observed the effect of a nonsteroidal anti-inflammatory drug, naproxen, used in the treatment of degenerative articular diseases, during the process of actinotrichia regeneration. For this purpose, regenerating tissue from animals in contact with the drug was submitted to histochemical and ultrastructural analysis in comparison to tissue from animals under normal conditions, i.e., not in contact with the drug in question. Actinotrichia regeneration was similar in both animals, indicating that naproxen, at the dose used in the present study, did not interfere with actinotrichia synthesis during the regenerative process of the tail fin. This could be because naproxen did not influence the expression of the genes required for the regeneration process, such as the Sonic hedgehog (Shh) gene, which is involved in actinotrichia formation.

A borda da nadadeira caudal de teleósteo é sustentada por um conglomerado de espículas pequenas, rígidas e fusiformes chamadas actinotriquias. Essas estruturas, após a amputação, apresentam uma capacidade regenerativa extremamente rápida. Neste trabalho estudamos o efeito de uma droga anti-inflamatória não esteroide, o naproxeno, utilizada no tratamento de doenças articulares degenerativas, durante o processo de regeneração da actinotriquia. Para isso foram feitas análises histoquímicas e ultraestruturais do tecido em regeneração de animais em contato com a droga comparada com animais em condições normais, ou seja, sem contato com a droga em questão. Os animais em contato com a droga apresentaram a regeneração da actinotriquia de modo semelhante ao dos animais mantidos em condições normais, indicando que o naproxeno, na dose utilizada neste trabalho, não interferiu na síntese das actinotriquias durante o processo regenerativo da nadadeira caudal. Isto talvez seja porque o naproxeno não tenha influenciado a expressão dos genes necessários para o processo de regeneração, tal como o gene Sonic hedgehog (Shh), que está envolvido na formação da actinotriquia.

Hemidactylus frenatus (Squamata: Gekkonidae): call frequency, movement and condition of tail in Costa Rica

Call frequency and movements of the gecko Hemidactylus frenatus were studied in Punta Morales, Costa Rica from April 1999 through May 2000. Call activity of H. frenatus was positively related to air temperature at night and throughout the year. Higher activity was at dusk, dawn, and during the hottest months. Call frequency was related with gecko abundance per month, although not during the night. More males and females had a regenerated tail compared to juveniles, the last ones could have it complete or regenerated. Females moved longer distances than males and juveniles. Adults were found higher on walls. Males and females were recaptured more times than juveniles, and the period of time between their recaptures was longer. Members of this population do not seem to be as aggressive to other geckos as mentioned in the literature.

Estudié la frecuencia de canto y el desplazamiento de la lagartija Hemidactylus frenatus en Punta Morales, Costa Rica. La frecuencia de canto se corelaciona positivamente con la temperatura ambiental durante la noche y con la temperatura a lo largo del año. La mayor actividad fue al anochecer, al amanecer y durante los meses más calurosos. La abundancia mensual de lagartijas se relacionó con la frecuencia de canto, no así la abundancia por noche. Las colas regeneradas son más frecuentes en hembras y machos que en las lagartijas jóvenes. Las hembras se desplazaron mayores distancias que machos y jóvenes. Los adultos se encontraban más alto en las paredes de los edificios. Los machos y hembras se recapturaron más veces que los jóvenes, y el tiempo entre recapturas fue mayor. Esta población no parece ser tan agresiva como se menciona en la literatura.

Complement-mediated tail degradation of Neodiplostomum seoulense cercariae

The furcocercus cercariae of Neodiplostomum seoulense (Digenea: Neodiplostomidae) penetrate the skins of tadpoles and shed their tails. The speculated mechanism of this tail loss was physical efforts required to produce a vigorous zigzag motion during skin penetration; no other mechanism has been proposed. We examined the relationship between the host serum and cercarial tail loss. Cercariae of N. seoulense were collected from experimentally infected Segmentina hemisphaerula, and lots of 300 cercariae were cultured in medium 199 contained several types of sera. Cercarial tail degradation was induced in all media, but all the cercariae cultured except those cultured in media containing fetal bovine serum (FBS) died within 48 hr. After 72 hr cultivation in media containing FBS, cercarial tail degradation was induced in 67.0%; in continuous cultivation 13.3% of larvae survived for 7 days. Tail degradation did not occur in the absence of serum and when serum was heat inactivated at 56 degrees C for 30 min. The addition of 20 mM ethylenediaminetetraacetic acid (EDTA) blocked cercarial tail degradation completely. Moreover, the addition of 20 mM MgCl2 restored tail degradation blocked by EDTA. These results suggest that the alternative complement pathway is related with the N. seoulense cercarial tail degradation induced by serum.

Effect of repeated stress on novelty-induced antinociception in rats

There is extensive evidence that acute stress induces an analgesic response in rats. On the other hand, repeatedly stressed animals may present the opposite effect, i.e., hyperalgesia. Furthermore, exposure to novelty is known to induce antinociception. The effects of repeated restraint stress on nociception after exposure to novelty, as measured by the tail-flick latency (TFL), were studied in adult male rats. The animals were stressed by restraint 1 h daily, 5 days a week for 40 days. The control group was not submitted to restraint. Nociception was assessed with a tail-flick apparatus. After being familiarized with the TFL apparatus, each group was subdivided into two other groups, i.e., with or without novelty. Animals were subjected to the TFL measurement twice. For the animals exposed to novelty, the first TFL measurement was made immediately before, and the second 2 min after a 2-min exposure to a new environment. While the control group presented an increased TFL after exposure to a novel environment, chronically stressed animals did not show this effect. These results suggest that repeated restraint stress induces an alteration in the nociceptive response, perhaps as a result of an alteration in endogenous opioids in these animals

Estudo preliminar de analgesia por eletroacupuntura em ratos Wistar observados no "Tail Flick": efeito do estresse em contensor na motilidade da cauda do rato / Preliminary study of analgesia by electroacupuncture in Wistar rats observed on Tail Flick: stress effects of contention on the tail motility of the rats

Este estudo tem por finalidade relacionar o efeito do estresse em contensor com o número de movimentos craniais e caudais do rato, a fim de estabelecer um padräo de movimento normal do rato. Material - 10 ratos Wistar, fêmeas adultas de 200-220g, contensor metálico, aparelho Tail Flick, cronômetro. Método - As ratas foram observadas durante 20 minutos dentro do contensor, sendo avaliados os tempos de capturas e números de tentativas de fuga do animal durante o experimento. E, após a acalmia das ratas dentro do contensor, foram registrados o número de movimentos cefálicos e caudais de cada animal, registrando-se também o tempo de ocorrência de cada movimento. Resultados - A análise de variância por postos de Friedman mostrou aumento significativo do número de movimentos caudais com o decorrer do tempo de contensäo. Entretanto, pelo teste de Kappa de concordância, obteve-se fraca concordância entre movimentos cefálicos e caudais. Conclusäo - Os movimentos caudais das ratas entre o 16§ e 20§ minutos após a contensao foram significantemente maiores do que no 4§ e 8§ minutos e 8§ e 12§ minutos.

Involvement of adrenergic & cholinergic mechanisms in analgesia electrically induced from pretectal nucleus of rat.

Analgesia induced by pretectal stimulation in rat was analysed using suitable antagonists. Mild electrical stimulation of sites in the pretectal nucleus (PTN) caused analgesia of long duration, without signs of aversion and unassociated with motor deficit. Pretreatment of animals with ip atropine sulphate (1 mg/kg), phenoxybenzamine (5 mg/kg), sotalol (2 mg/kg) and haloperidol (1 mg/kg) but not with saline, markedly reduced the antinociceptive response to PTN stimulation. Mild PTN stimulation thus seems to induce potent and long lasting analgesia in rats probably involving multisynaptic antinociceptive pathway(s).