ESS - CF - Ciências Funcionais
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- In vitro metabolism of steroid hormones by ovary and hepatopancreas of the crustacean Penaeid shrimp Marsupenaeus japonicusPublication . Summavielle, Teresa; Monteiro, Pedro Ribeiro Rocha; Reis-Henriques, Maria Armanda; Coimbra, João; Monteiro, Pedro; Summavielle, TeresaRadioimmunoassay (RIA) was applied to identify selected metabolites obtained in in vitroincubations of ovarianand hepatopancreatic tissues from female Marsupenaeus japonicusin previtellogenic and vitellogenic maturation stages. Depend-ing on the precursors used, progesterone, 17α-hydroxyprogesterone or testosterone, it was possible to observe the presence of sev-eral enzymatic activities through metabolites detected in incubations. The present study provides evidence that the ovary of theshrimpM. japonicusis capable of synthesising 17β-estradiol from progesterone, evidencing the presence of 17α-hydroxy-lase, C17-C20lyase, 17β-hydroxysteroid dehydrogenase (17β-HSD) and aromatase. Enzymatic activities of aromatase, 3β-HSD and 17α-hydroxylase were detected in hepatopancreas, but not that of C17-C20lyase. These results suggest that 17β-estradiol could be the vitellogenesis stimulating ovarian hormone (VSOH), and together with former in vivoand in vitrostudies this leads us to propose that in fact there may be a physiological role for steroid hormones in the maturation cycleof crustaceans.
- Abnormal immunoreactivity to serotonin in cerebellar purkinje cells after neonatal cocaine exposurePublication . Summavielle, Teresa; Alves, Cecília J.; Monteiro, Pedro; Tavares, Maria AméliaNeonatal cocaine is known to affect the developing serotonergic system in many brain structures, including the cerebellum. Changes in the cerebellar Purkinje cells after drug exposure are well documented and result in impairment of movement and other cerebellar disorders such as ataxia. These cells have a major postnatal developmental pattern; therefore, neonatal exposure to cocaine is likely to affect them. In this work, male and female Wistar rats were injected with 15 mg of cocaine hydrochloride/kg body weight/day, subcutaneously, in two daily doses, from postnatal day 1 (PND1) to PND29. Controls were given 0.9% of saline. On PND14, PND21, and PND30, rats were transcardially perfused, and brains removed and cryoprotected. Coronal sections from the cerebellum were processed for immunocytochemistry of cells containing serotonin (5-hydroxytryptamine, or 5-HT). At the same postnatal age, rats from at least three different litters were sacrificed by decapitation, and brains were dissected for determination of 5-HT in the cerebellum by high-performance liquid chromatography with electrochemical detection. Upon the expected distribution of immunoreactivity to 5-HT, an abnormal immunoreactivity to 5-HT was observed in the Purkinje cells of six cocaineexposed animals, but not in control animals. Also, levels of cerebellar 5-HT in cocaine-exposed rats were significantly increased on PND21. These results, together with previously reported observations of altered patterns of motor behavior, indicate that neonatal cocaine exposure affects the serotonergic cerebellar system, altering the standard development of Purkinje cells and possibly compromising the motor function.
- Prenatal cocaine exposure: effects on locomotor activity in rat offspringPublication . Magalhães, Ana; Summavielle, Teresa; Melo, Pedro; Tavares, Maria Amélia; Sousa, Liliana de; Summavielle, TeresaThis study examines the developmental effects of prenatal exposure to cocaine in the rat, evaluated during the first month of life through open-field behavior. The offspring of Wistar dams that received 60 mg/kg of cocaine, from gestational day 8 to 22, were examined in the open-field during the second, third and fourth weeks of postnatal life in three consecutive 15-min daily sessions, starting on postnatal day (PND) 14, (PND 14–16), PND 21 (PND 21–23) and PND 28 (PND 28–30). Results show that prenatal exposure to cocaine increased total activity and rearing behavior on PND 22 and PND 29. Also, on PND 14, cocaine-exposed animals reared significantly more than control rats. There were no significant differences in the frequency of center and peripheral ambulation, nor in the defecation rate. The present results evidence alterations in the emotional behavior of rats prenatally exposed to cocaine. The delayed onset of exploration in the open-field observed in cocaine-exposed animals suggests that they take more time to become habituated to a novel and open environment.
- Effects of neonatal exposure to methamphetamine: Catecholamine levels in brain areas of the developing ratPublication . Silva, Joana Gomes da; Miguel, Rosário de; Fernández-Ruiz, Javier; Summavielle, Teresa; Tavares, M. Amélia; Summavielle, TeresaNeonatal exposure to moderate doses of methamphetamine during the first month of life in the rat affects tyrosine hydroxylase gene expression in the substantia nigra and nigrostriatal tyrosine hydroxylase activity. The main goal of this work was to evaluate the ontogeny of the neurochemical effects of repeated exposure to moderate doses of methamphetamine during the first month of life in the rat. Norepinephrine, dopamine, and dihydroxyphenylacetic acid levels were measured in target areas of methamphetamine: the substantia nigra, ventral tegmental area, caudate-putamen, nucleus accumbens, and medial prefrontal cortex. On postnatal day 1 (PND1), Wistar rat litters, culled to eight pups, sex balanced, were randomly attributed to either methamphetamine or control groups. Methamphetamine groups were administered 10 mg of (±)-methamphetamine/kg body weight/day, subcutaneously, from PND1 until the day prior to sacrifice; control groups received isovolumetric saline. Groups were sacrificed on PND7, PND14, and PND30. Neonatal methamphetamine exposure increased norepinephrine levels in the substantia nigra of PND30 rats; on PND14, this variation was evident only in male pups. In the substantia nigra, the dihydroxyphenylacetic/dopamine ratio was also affected in PND30 males. In the ventral tegmental area, catecholamine levels were not affected by methamphetamine. Norepinephrine levels were also increased in the caudate-putamen of PND7 male and PND14 female methamphetamine-exposed pups and in the nucleus accumbens of PND14 female and PND30 male and female pups. Catecholamine levels in the medial prefrontal cortex were not affected by neonatal methamphetamine administration.
- Effects of postnatal cocaine exposure and environmental enrichment on rat behavior in a forced swim testPublication . Magalhães, Ana; Summavielle, Teresa; Tavares, Maria Amélia; Sousa, Liliana de; Summavielle, TeresaThis study examined the effects of environmental enrichment on rats exposed to cocaine during the first month of life, in several categories of behavior observed in a forced swim test. Wistar rats were divided in four groups. The first included pups that were subjected to injections of cocaine hydrochloride (15 mg/kg body weight/day, subcutaneously, in two daily doses, from postnatal days 1 to 27) and reared in an enriched environment (CocEE); the second, pups that were subjected to injections of cocaine (as previously described) and reared in a standard environment (CocSE); the third, pups that were subjected to saline injections and reared in an enriched environment (SalEE); the fourth, pups that were subjected to saline injections and reared in a standard environment (SalSE). On postnatal days 26 and 27, rats were tested in a swimming pool in two 5-min sessions. The categories of behavior studied in this work were: fast swim, slow swim, struggling, diving, and immobility. Results showed that postnatal cocaine exposure decreased the time spent on fast swim during the two sessions and increased the immobility behavior during the second session in CocSE pups compared with SalSE pups. SalEE pups increased the time spent in fast swim, slow swim, and diving, and decreased the time spent in struggling and immobility during the two sessions compared with SalSE pups. CocEE animals spent more time in fast swim and struggling and less the time in immobility compared with CocSE pups. The present results suggest that postnatal cocaine exposure affects the ability of these animals to cope with stressful situations, and that environmental enrichment seems to enable the rats to adopt a more active strategy, one that allows them to better cope with this particular stress situation.
- Prenatal exposure to cocaine and enriched environmentPublication . Magalhães, Ana; Summavielle, Teresa; Melo, Pedro; Rosa, Rui; Tavares, Maria Amélia; Sousa, Liliana deExposure to cocaine throughout gestation may produce several deleterious outcomes in the offspring that include effects on neurotransmitter systems and structure of the central nervous system. Such changes are most likely correlated with behavioral alterations. Environmental enrichment (EE) in early stages is a factor that affects structural and behavioral development. This article examines the effects, upon social interactions, of EE during the first month of life in rats prenatally exposed to cocaine. Wistar dams were subcutaneously exposed to 60 mg/kg of cocaine divided in two daily doses from gestational day (GD)8 to GD22. Pair-fed controls were given saline vehicle in the same protocol. Offspring were distributed to the different environments in four experimental groups. Group 1: offspring from dams prenatally exposed to cocaine as previously described and reared in EE from postnatal day (PND)1 to PND28; Group 2: pups from cocaine-exposed dams and reared in a standard environment (SE); Group 3: pups from pair-fed saline-exposed dams and reared in EE; Group 4: offspring from saline-exposed dams and reared in SE. On PND21, 24, and 28, rats were examined in several social behavioral categories (play fighting, social investigation, comfort behaviors, and solicitation to play) for 10 min. Animals reared in SE do not display any differences due to treatment in the behavioral categories analyzed. Control offspring reared in EE presented decreased play fighting, decreased solicitation to play, and decreased social investigation compared to the control SE group, while cocaine-exposed animals reared in EE did not present these variations. These results suggest that EE rearing may unmask hidden effects of prenatal cocaine exposure.
- MDA in adolescent male rats - decreased serotonin in the amygdala and behavioral effects in the elevated plus-maze testPublication . Faria, Raquel; Magalhães, Ana; Monteiro, Pedro; Silva, Joana Gomes da; Tavares, Maria Amélia; Summavielle, TeresaLong-term behavioral consequences of the neurotoxicity produced by 3,4-methylenedioxymethamphetamine (MDMA) in the adolescent rat are still mostly unknown. Here, adolescent male rats (postnatal day 45 PND [45]) were exposed to 10 mg/kg of MDMA, intraperitoneally, every 2 h for 6 h. Controls were given 0.9% saline in the same protocol. Ten days after exposure, the behavioral effects of MDMA were assessed in the elevated plus-maze (n = 6 per group). After behavioral testing, animals were sacrificed and the amygdalae were dissected and processed for HPLC determination of dopamine (DA), serotonin (5-HT), and metabolites. Results showed a significant decrease in the 5-HT content (P < 0.05), but no significant alterations in DA or its metabolites. Behavioral observation in the elevated plus-maze showed a decreased number of entries in the unprotected arms (P < 0.05), which were correlated to the number of entries and time spent in the central platform. Rearing was also decreased (P < 0.05). No differences were observed in head dips, grooming, or number of entries in the protected arms of the apparatus. Therefore, we conclude that, as in the adult rat, exposure to MDMA in the adolescent rat is associated to long-term depletion of the 5-HT content and increased anxiety-like behavior.
- Postnatal exposure to cocaine in rats housed in an enriched environment: effects on social interactionsPublication . Magalhães, Ana; Summavielle, Teresa; Tavares, Maria Amélia; Sousa, Liliana deThis study was undertaken to evaluate the effects of environmental enrichment (EE) in rats exposed to cocaine during the first month of postnatal life by examining several categories of social behaviour (play fighting, social investigation, comfort behaviours and invitation to play). Wistar rats were divided in four groups: pups exposed to cocaine hydrochloride (15 mg/kg body weight/day), sc, in two daily doses, from postnatal day (PND) 1 to 28 and reared in EE; exposed to cocaine as previously described and reared in standard environment (SE); saline-exposed and reared in EE; pups saline-exposed and reared in SE. On PND 21, 24 and 28, social interactions were examined for 10 min. Results show that cocaine animals reared in SE decreased the frequency of play solicitation. Control animals reared in EE exhibited decreased play fighting and social investigation behaviours compared to SE-reared rats. Animals postnatally exposed to cocaine when reared in EE displayed more comfort and invitation to play behaviours and decreased social investigation compared with SE-reared animals. The results suggest that in rats postnatally exposed to cocaine, EE rearing elicited differences in both processing of environmental stimuli and a response to social challenges. Human & Experimental Toxicology (2007) 26, 303-309
- Hormonal, neurochemical, and behavioral response to a forced swim test in adolescent rats throughout cocaine withdrawalPublication . Alves, Cecília Juliana; Magalhães, Ana; Summavielle, Teresa; Melo, Pedro; Sousa, Liliana De; Tavares, Maria Amélia; Monteiro, PedroThe use of cocaine in adults has been linked to depression and/or anxiety. Several studies have shown an association between cocaine-primed craving and depressive symptoms. In animal models, the forced swim test (FST) is frequently used for screening depressive-like behavior. This study aimed to verify the presence of depression-like symptoms in adolescent rats after chronic cocaine exposure by analyzing behavior in a FST. The subsequent alterations in neurotransmitters and hypothalamus-pituitary-adrenal axis activity induced by this test were also analyzed. Both male and female adolescent Wistar rats were submitted to a chronic “binge” pattern of administration of cocaine hydrochloride, and subjects were tested in a forced swim test 2 days after cocaine's last administration. At the end of the behavioral test, trunk blood was collected for quantification of corticosterone plasma levels, and hypothalamus, prefrontal cortex, amygdala, and hippocampus were dissected for neurochemical determinations. No significant differences were found in the behavior on the FST of both males and females after withdrawal from chronic cocaine administration. Nevertheless, plasma levels of corticosterone were increased in cocaine-treated males, although not significantly (P= 0.065). In females cocaine failed to affect corticosterone levels. Of interest, neurochemical analyses showed that dopamine turnover was decreased in amygdala in cocaine-treated males (not significantly, P= 0.055). No significant differences were found on neurotransmitter levels in the other brain regions analyzed. Withdrawal from chronic cocaine administration during adolescence did not have a significant effect on stress-induced behavioral alterations, although the neurochemical response to the stressful situation provided by FTS seemed to be affected.
- Exploratory behavior in rats postnatally exposed to cocaine and housed in an enriched environmentPublication . Magalhães, Ana; Melo, Pedro; Alves, Cecília Juliana; Tavares, Maria Amélia; Sousa, Liliana De; Summavielle, TeresaExposure to cocaine in early periods of postnatal life is usually associated with changes in development of neurotransmitter systems and structure of the central nervous system. Such changes are most likely correlated with behavioral alterations. Environmental enrichment conditions (EC) in early stages is a factor that affects structural and behavioral development. The purpose of this study is to examine the effects of EC on rats postnatally exposed to cocaine on exploratory behavior. Wistar rats were as signed to four groups—Group 1: pups exposed to cocaine hydrochloride (15 mg/kg body weight/day) s.c., in two daily doses, from postnatal day (PND) 1 to 28 and reared in EC; Group 2: pups exposed to cocaine as previously described and reared in a stan dard environmental conditions (SC); Group 3: pups saline-injected and reared in EC; and Group 4: pups saline-injected and reared in SC. On PND 21, 24, and 28, groups of four rats (to reduce anxiety) were placed for 10 minutes into an arena with sev eral objects. The following exploratory behavioral categories were examined: object interaction, exploration, manipulation, approximation, and total time of object contact. Animals from Group 2 showed decreased object interaction and total contact on PND 21. Control offspring reared in EE showed decreases in exploratory behavior at all ages analyzed compared with the control SE group, while cocaine-exposed animals reared in EC showed decreased object interaction, object approximation, and total exploratory behavior. The results in this group suggest that EC improved information acquisition and memory processes in animals postnatally exposed to cocaine.