Abstract The Caatinga is dominated by a semiarid climate and a high plant biodiversity dealing with anthropogenic disturbance and climate change. Previous studies suggest that Caatinga became a completely soil-water pulse-dominated forest in response to reduced water availability at the end of the last ice age, around 10 cal kyr BP. This work aimed to identify vegetative and climatic evolution, and the human influence in the Cariri region, one of the driest parts of Brazil. We sampled soil in a temporal pond to identify pollen. The testimony is 170 cm in lenght and achieves 6,216 cal yr BP at the base. Pollen analysis indicates the presence of taxa representative of humid climates, between 6,216 and ca. 5000 cal yr BP, like Azolla, followed by implantation of Caatinga's modern configuration from ca. 4,900 cal yrs BP. After 2,700 cal yr BP, humid episodes occurred, possibly related to the El Niño - La Niña variation across the region, marked by increased algae and aquatic herbs concentrations. The occurrence of human activity species like Caryocar, Dioscorea, Spondias, and Licania suggest possibly landscape manipulation by pre - Columbian populations, and exotic Pinus and Prosopis reveal changes in the tree cover caused by European colonization in the Caatinga.

Resumen La Caatinga está dominada por un clima semiárido y una alta biodiversidad vegetal que se enfrenta a la perturbación antropogénica y al cambio climático. Estudios previos sugieren que Caatinga se convirtió en un bosque completamente dominado por pulsos de suelo y agua en respuesta a la disponibilidad reducida de agua al final de la última edad de hielo, alrededor de 10 cal kyr BP. Este trabajo tuvo como objetivo identificar la evolución vegetativa y climática, y la influencia humana en la región de Cariri, una de las partes más secas de Brasil. Tomamos muestras del suelo en un estanque temporal para identificar el polen. El testimonio mide 170 cm de largo y alcanza 6.216 cal año BP en la base. El análisis de polen indica la presencia de taxones representativos de climas húmedos, entre 6.216 y ca. 5000 cal año AP, como Azolla, seguido de implantación de la configuración moderna de Caatinga desde ca. 4.900 años cal BP. Después de 2700 años calóricos AP, ocurrieron episodios húmedos, posiblemente relacionados con la variación de El Niño - La Niña en la región, marcados por un aumento de las concentraciones de algas y hierbas acuáticas. La presencia de especies de actividad humana como Caryocar, Dioscorea, Spondias y Licania sugieren una posible manipulación del paisaje por parte de las poblaciones precolombinas, y las exóticas Pinus y Prosopis revelan cambios en la cobertura arbórea causados por la colonización europea en la Caatinga.

Resumo A Caatinga é dominada por um clima semiárido e uma alta biodiversidade vegetal que lida com distúrbios antrópicos e mudanças climáticas. Estudos anteriores sugerem que a Caatinga se tornou uma floresta totalmente dominada pelo pulso de água do solo em resposta à redução da disponibilidade de água no final da última era glacial, por volta de 10 cal kyr AP. Este trabalho teve como objetivo identificar a evolução vegetativa, climática e a influência antrópica na região do Cariri, uma das regiões mais secas do Brasil. Amostramos o solo em uma lagoa temporal para identificar o pólen. O testemunho tem 170 cm de comprimento e atinge 6.216 anos cal BP na base. A análise polínica indica a presença de táxons representativos de climas úmidos, entre 6.216 e ca. 5000 anos cal AP, como Azolla, seguido pela implantação da configuração moderna da Caatinga de ca. 4.900 anos cal BP. Após 2.700 anos cal AP, ocorreram episódios úmidos, possivelmente relacionados à variação El Niño - La Niña na região, marcados pelo aumento da concentração de algas e ervas aquáticas. A ocorrência de espécies de atividade humana como Caryocar, Dioscorea, Spondias e Licania sugerem possivelmente manipulação da paisagem por populações pré-colombianas, e as exóticas Pinus e Prosopis revelam mudanças na cobertura arbórea causadas pela colonização européia na Caatinga.

Preclinical studies have shown that repeated stress experiences can result in an increase in the locomotor response to the subsequent administration of drugs of abuse, a phenomenon that has been termed behavioral cross-sensitization. Behavioral sensitization reflects neuroadaptive processes associated with drug addiction and drug-induced psychosis. Although cross-sensitization between stress- and drug-induced locomotor activity has been clearly demonstrated in adult rats, few studies have evaluated this phenomenon in adolescent rats. In the present study, we determined if the simultaneous exposure to stress and nicotine was capable of inducing behavioral sensitization to nicotine in adolescent and adult rats. To this end, adolescent (postnatal day (P) 28-37) and adult (P60-67) rats received nicotine (0.4 mg/kg, sc) or saline (0.9% NaCl, sc) and were immediately subjected to restraint stress for 2 h once a day for 7 days. The control group for stress was undisturbed following nicotine or saline injections. Three days after the last exposure to stress and nicotine, rats were challenged with a single dose of nicotine (0.4 mg/kg, sc) or saline and nicotine-induced locomotion was then recorded for 30 min. In adolescent rats, nicotine caused behavioral sensitization only in animals that were simultaneously exposed to stress, while in adult rats nicotine promoted sensitization independently of stress exposure. These findings demonstrate that adolescent rats are more vulnerable to the effects of stress on behavioral sensitization to nicotine than adult rats.

Several lines of evidence indicate that the use of stimulant drugs, including methylphenidate (MPD), increases tobacco smoking. This has raised concerns that MPD use during adolescence could facilitate nicotine abuse. Preclinical studies have shown that repeated treatment with an addictive drug produces sensitization to that drug and usually cross-sensitization to other drugs. Behavioral sensitization has been implicated in the development of drug addiction. We examined whether repeated oral MPD administration during adolescence could induce behavioral sensitization to MPD and long-lasting cross-sensitization to nicotine. Adolescent male Wistar rats were treated orally with 10 mg/kg MPD or saline (SAL) from postnatal day (PND) 27 to 33. To evaluate behavioral sensitization to MPD in adolescent rats (PND 39), the SAL pretreated group was subdivided into two groups that received intragastric SAL (1.0 mL/kg) or MPD (10 mg/kg); MPD pretreated rats received MPD (10 mg/kg). Cross-sensitization was evaluated on PND 39 or PND 70 (adulthood). To this end, SAL- and MPD-pretreated groups received subcutaneous injections of SAL (1.0 mL/kg) or nicotine (0.4 mg/kg). All groups had 8 animals. Immediately after injections, locomotor activity was determined. The locomotor response to MPD challenge of MPD-pretreated rats was not significantly different from that of the SAL-pretreated group. Moreover, the locomotor response of MPD-pretreated rats to nicotine challenge was not significantly different from that of the SAL-pretreated group. This lack of sensitization and cross-sensitization suggests that MPD treatment during adolescence does not induce short- or long-term neuroadaptation in rats that could increase sensitivity to MPD or nicotine.