Anxiolytic and panicolytic-like effects of environmental enrichment seem to be modulated by serotonin neurons located in the dorsal subnucleus of the dorsal raphe.

In a previous study, we showed that exposure of rats to a one-week environmental enrichment (EE) protocol decreases elevated T-maze (ETM) avoidance responses, an anxiolytic-like effect, without altering escape reactions, in clinical terms related to panic disorder. These anxiolytic-like effects were followed by decreased delta FosB-immunoreactivity (delta FosB-ir) in the cingulate cortex, dorsolateral and intermediate lateral septum, hippocampus (cornus of Ammon), anterior and dorsomedial hypothalamus, medial and basolateral amygdala and ventral region of the dorsal raphe nucleus. The purpose of the present study was to further investigate behavioral and neurophysiological alterations induced by EE exposure. For that, in a first experiment we verified if increasing the time of exposure to the same EE protocol used in our previous study (from one to two weeks) altered male Wistar rats' ETM escape responses. All animals were tested in an open field, immediately after the ETM, for locomotor activity assessment. Since anxiety and panic-related reactions have been associated to the functioning of specific subnuclei of the dorsal raphe nucleus (DR), we also evaluated delta FosB-ir in serotonergic cells of DR regions. At last, we analyzed plasma corticosterone levels in animals submitted to EE and to standard housing. Results showed that a two-week exposure to EE decreases both ETM avoidance and escape reactions, inducing anxiolytic and panicolytic-like effects, respectively. There was also a significant decrease in the number of double staining neurons in the midrostral region of the dorsal subnucleus of the dorsal raphe. No changes in corticosterone levels, however, were observed. These results contribute to a better understanding of the effects of EE on anxiety and panic-related responses.

Environmental enrichment decreases avoidance responses in the elevated T-maze and delta FosB immunoreactivity in anxiety-related brain regions.

Environmental enrichment (EE) is an animal management technique, which seems to improve adaptation to the experimental conditions of housing in laboratory animals. Previous studies have pointed to different beneficial effects of the procedure in the treatment of several disorders, including psychiatric conditions such as depression. The anxiolytic effects induced by EE, on the other hand, are not as clear. In fact, it has been proposed that EE acts as a mild stressor agent. To better understand the relationship of EE with anxiety-related responses, the present study exposed rats to one week of EE and subsequently tested these animals in the inhibitory avoidance and escape tasks of the elevated T-maze (ETM). In clinical terms, these responses have been respectively related to generalized anxiety and panic disorder. All animals were tested in an open field, immediately after the ETM, for locomotor activity assessment. Additionally, analysis of delta FosB protein immunoreactivity (FosB-ir) was used to map areas activated by EE exposure and plasma corticosterone measurements were performed. The results obtained demonstrate that exposure to EE for one week impaired avoidance responses, an anxiolytic-like effect, without altering escape reactions. Also, in animals submitted to the avoidance task EE exposure decreased FosB-ir in the cingulate cortex, dorsolateral and intermediate lateral septum, hippocampus (cornus of Ammon), anterior and dorsomedial hypothalamus, medial and basolateral amygdala and ventral region of the dorsal raphe nucleus. Although no behavioral differences were observed in animals submitted to the escape task, EE exposure also decreased FosB-ir in the cingulate cortex, hippocampus (dentate gyrus), lateral amygdala, paraventricular, anterior and ventromedial hypothalamus, dorsomedial periaqueductal gray and ventral and dorsal region of the dorsal raphe. No changes in corticosterone levels, however, were observed. These results contribute to a better understanding of the effects of EE on anxiety.

Unpredictable chronic mild stress exerts anxiogenic-like effects and activates neurons in the dorsal and caudal region and in the lateral wings of the dorsal raphe nucleus.

In previous studies, we verified that exposure to unpredictable chronic mild stress (UCMS) facilitates avoidance responses in the elevated T-maze (ETM) and increased Fos-immunoreactivity in different brain structures involved in the regulation of anxiety, including the dorsal raphe (DR). Since, it has been shown that the DR is composed of distinct subpopulations of serotonergic and non-serotonergic neurons, the present study investigated the pattern of activation of these different subnuclei of the region in response to this stress protocol. Male Wistar rats were either unstressed or exposed to the UCMS procedure for two weeks and, subsequently, analyzed for Fos-immunoreactivity (Fos-ir) in serotonergic cells of the DR. To verify if the anxiogenic effects observed in the ETM could be generalized to other anxiety models, a group of animals was also tested in the light/dark transition test after UCMS exposure. Results showed that the UCMS procedure decreased the number of transitions and increased the number of stretched attend postures in the model, an anxiogenic effect. UCMS exposure also increased Fos-ir and the number of double-labeled neurons in the mid-rostral subdivision of the dorsal part of the DR and in the mid-caudal region of the lateral wings. In the caudal region of the DR there was a significant increase in the number of Fos-ir. No significant effects were found in the other DR subnuclei. These results corroborate the idea that neurons of specific subnuclei of the DR regulate anxiety responses and are differently activated by chronic stress exposure.

Relation between the level of self-mutilation and the concentration of fecal metabolites of glucocorticoids incaptive chimpanzees (Pan troglodytes) / Relação do grau de automutilação com as concentrações de metabólitos fecais de glicocorticoides em chimpanzés (Pan troglodytes)

The influence of stress in an environment, according with the behavioral and endocrine variables of primates, are increasingly being studied by a diversity of authors, and have shown that abnormal behaviors associated with increased glucocorticoids may be directly related with the impairment of their well-being. In this work were used 22 adult chimpanzees (Pan troglodytes), 11 males and 11 females, kept in captivity in three different institutions. All animals had their behavior registered by focal session using a 30 seconds sample interval, during six months, totaling 4,800 registries per each animal. During this period, fecal samples were collected 3 times a week for the extraction and measurement of the concentration of fecal metabolites of glucocorticoid by radioimmunoassay. Of the total observed, stereotypical behaviors represented 13,45±2.76%, and among them, self-mutilation represented 38.28±3.98 %. The animals were classified into three different scores, according with the percentage of body surface with alopecia due to self-mutilation. It was found a positive correlation of high intensity between the scores of alopecia due to the observed mutilation and the average concentrations of fecal metabolites of glucocorticoids. This result strongly suggests that this measurement of self-mutilation in a chimpanzee can be used as an important auxiliary tool to evaluate de conditions of adaptation of an animal in captivity, functioning as a direct indicator of the presence of chronic stress...

A influência do estresse de um ambiente nas variáveis endócrino-comportamentais de primatas vem sendo cada vez mais estudada por diversos autores, e mostram que comportamentos anormais associados a aumentos de glicocorticóides podem estar diretamente relacionados ao comprometimento do bem-estar. Neste trabalho foram utilizados 22 chimpanzés (Pan troglodytes) adultos, sendo 11 machos e 11 fêmeas mantidos em cativeiro de três instituições diferentes. Todos os animais tiveram seus comportamentos registrados pelo método de amostragem focal por intervalo de tempo, durante seis meses, totalizando 4800 registros para cada animal. Amostras fecais foram coletadas três vezes por semana, durante este período, para extração e dosagem de metabólitos fecais de glicocorticoides por radioimunoensaio. Os comportamentos estereotipados representaram 13,45+2,76% do total observado, sendo que dentre estes comportamentos a automutilação representou 38,28+3,98%. Os animais foram classificados em três graus diferentes, de acordo com o percentual da superfície corpórea com alopecia decorrente da automutilação. Foi encontrada uma correlação positiva de intensidade forte entre os graus de alopecia decorrentes de mutilação observados e as médias de concentrações de metabólitos fecais de glicocorticoides. Este resultado sugere fortemente que esta graduação de automutilação de um chimpanzé possa ser utilizada como uma ferramenta auxiliar importante nas avaliações das condições de adaptação do animal ao cativeiro, atuando como um indicador indireto da presença de estresse crônico...

Immunohistochemical study of the digestive tract of Oligosarcus hepsetus.

AIM: To describe the histology of the digestive tract and to investigate the occurrence of endocrine cells in Oligosarcus hepsetus (O. hepsetus). METHODS: The digestive tract (DT) of O. hepsetus was divided into esophagus, two stomach regions (glandular and non-glandular) and two intestinal regions (anterior and posterior). These specimens were processed by routine histological techniques and stained with hematoxylin-eosin, Gomori's trichrome, periodic acid Schiff (PAS) and Alcian blue (AB). An immunohistochemical method using avidin-biotin-peroxidase was employed. RESULTS: The esophagus is lined with a non-keratinized stratified squamous epithelium that is reactive to PAS and AB. The stomach has a mucosa lined with a simple columnar epithelium with mucus-secreting cells that are reactive only to PAS. The intestine has a simple columnar epithelium with a brush border and goblet cells that are reactive to PAS and AB. Somatostatin, serotonin and cholecystokinin immunoreactive cells were identified throughout the DT. CONCLUSION: This study revealed adaptations for the species' diet and showed that the distribution and relative frequency of immunoreactive cells are similar to those of other fish.

Meningoencephalitis due to Listeria monocytogenes in a pregnant rhesus macaque (Macaca mulatta).

We here report a spontaneous case of meningoencephalitis due to Listeria monocytogenes in an adult primiparous rhesus macaque (Macaca mulatta) during an outbreak of listeriosis in an outdoor enclosure. Clinical signs included tremors, abnormal posture, and altered mental status. Hematology and analyses of cerebrospinal fluid were consistent with bacterial infection. Pure cultures of L. monocytogenes were recovered from the placenta-abortus, cerebrospinal fluid, and brain tissue. The macaque did not respond to treatment and was euthanized. Histopathologic examination of the brain revealed acute meningoencephalitis. This case represents an unusual clinical and pathologic presentation of listeriosis in a nonhuman primate in which the dam and fetus both were affected.