Natural killer activity in a medium-term multi-organ bioassay for carcinogenesis

Natural killer (NK) cell activity was evaluated after the initiation and promotion steps in a medium-term multi-organ bioassay for carcinogenesis. NK cell activity was assessed in vitro by Cr51 release assay at the 4th and 30th weeks of the experiment. Male Wistar rats were sequentially initiated with N-diethylnitrosamine (DEN i.p.), N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN drinking water), N-methyl-N-nitrosourea (MNU i.p.), dihydroxy-di-N-propylnitrosamine (DHPN drinking water) and N,N'-dimethylhydrazine (DMH s.c.) at subcarcinogenic doses for 4 weeks (DMBDD initiation). One group was evaluated at the 4th week and the other was maintained without any further treatment until the 30th week. Two initiated groups were exposed through the diet to 2-acetylaminofluorene (2-AAF) or phenobarbital (PB), from the 6th until the 30th week. Five additional groups were studied to evaluate the effects of each initiator on NK activity. All groups submitted to initiation only, initiation plus promotion, or promotion only, developed significantly more preneoplastic lesions than the untreated control group. The main target organs for tumor development in the initiated animals were the liver and the colon, irrespective of treatment with 2-AAF or PB. NK cell activity was not affected by exposure to genotoxic carcinogens after initiation, at the 4th week. Treatments only with PB or 2-AAF did not change NK cell activity. However, decreased NK cell activity was registered in the group only initiated with DMBDD and in the group given DMBDD+2-AAF. This late depression of NK cell activity at the 30th week could be related to the production of suppressing molecules by the tumor cells.

Role of the medial septal area on the cardiovascular, fluid and electrolytic responses to angiotensin II and cholinergic activation into the subfornical organ in rats

In the present study we investigated the effect of electrolytic lesion of the medial septal area (MSA) on the pressor and dipsogenic response to cholinergic activation and angiotensin II (ANGII) injection into the subfornical organ (SFO) in rats. In addition the effect of MSA lesion on the natriuresis, kaliuresis and diuresis after cholinergic activation of the SFO was also investigated. Sham- and MSA-lesioned rats with a stainless steel cannula implanted into the SFO was used. The injection of ANGII (12 ng) into the SFO in sham rats produced pressor (24 ± 2 mmHg) and dipsogenic (9.6 ± 1.1 ml/h) responses. MSA lesion, both acute (2-6 days) and chronic (15-19 days), reduced the pressor (14 ± 2 mmHg) and dipsogenic (2.7 ± 1 ml/h) responses to ANGII into SFO. The injection of the cholinergic agonist carbachol (2 nmol) into the SFO in sham rats produced pressor (48 ± 4 mmHg), dipsogenic (10 ± 1.2 ml/h), natriuretic (457 ± 58 μEq/2 h) and kaliuretic (249 ± 16 μEq/2 h) responses. Acute, but not chronic MSA lesion reduced the pressor (27 ± 3 mmHg), natriuretic (198 ± 55 μEq/2 h) and kaliuretic (128 ± 16 μEq/2 h) responses to carbachol into SFO. No change in the dipsogenic response to carbachol into the SFO was observed in MSA-lesioned rats. Antidiuresis after carbachol was observed only in MSA-lesioned rats. The present results show that the MSA plays a role on the pressor, natriuretic and kaliuretic responses to cholinergic activation of the SFO in rats and on the pressor and dipsogenic responses to ANGII into the same area. In addition, they provide circumstancial evidence for separate circuits subserving the dipsogenic response to central cholinergic and angiotensinergic activation. A facilited diuresis after MSA lesion is also suggested.

Medium and large-sized mammals in a private reserve of natural heritage in the municipality of Jaú, São Paulo, Brazil

Medium and large-sized mammals control invertebrate and vertebrate populations and are important seed dispersers. These animals are losing their territory and living range due to deforestation and the fragmentation of natural areas, particularly in the Atlantic Forest and Cerrado. The Private Reserve of Natural Heritage (PRNH) Amadeu Botelho is isolated from other forest fragments and is thus a wildlife refuge in the region of Jaú, central-western region of state of São Paulo, southeastem Brazil. Animals as such as the puma (Puma concolor), ocelot (Leopardus pardalis) and jaguarundi (Puma yagouaroundi) have been sighted in the reserve by wildlife guards and residents. This reserve, which belongs to “Santo Antônio dos Ipês” farm, is surrounded by several plantations, and is very close to the center of the city of Jaú. In addition to surveying the mammal species in the reserve, this study diagnosed the influence of the farm’s activities and the proximity to the center of the municipality of Jaú on the fauna under study