Biomedical subjects

F C Sousa

Publications and source records attributed to F C Sousa.

8 recordsLinked to original sources

PubMed2001

Different times of withdrawal from cocaine administration cause changes in muscarinic and dopaminergic receptors in rat premotor cortex.

The present work studied neurochemical changes in rat premotor cortex 30 min, 1 and 5 days after withdrawal from cocaine repeated administration (20 and 30 mg/kg, intraperitoneally, daily for 7 days). Binding assays were performed in 10% homogenates, and ligands used were [(3)H]-N-methylscopolamine, [(3)H]-SCH 23390, and [(3)H]-spiroperidol for muscarinic, D(1)- and D(2)-like receptors, respectively. Levels of cyclic AMP (cAMP) and cyclic guanosine monophosphate (cGMP) were determined using a commercial kit. Scatchard analyses of muscarinic receptors showed an upregulation after 1 and 5 days withdrawal. While D(2)-like receptors were upregulated at all withdrawal periods, D(1)-like receptors were upregulated only at the 30 min withdrawal, and returned to normal levels after 1 day of the last injection. In relation to cAMP levels, the repeated cocaine administration, 1 day after the last injection produced a decrease (around 26%) with both doses, while a 67% increase was seen in cGMP levels with the 30 mg/kg dose. These findings indicate lasting neurochemical changes in premotor cortex caused by cocaine which remained after different withdrawal periods.

Animals↗

PubMed2001

Effects of dopaminergic and cholinergic interactions on rat behavior.

The present work studied the effects of dopaminergic and muscarinic receptor agonists and antagonists on rat locomotor activity and catalepsy. Results showed that carbachol at the highest dose used (10 mg/kg, p.o.) decreased and pimozide at the dose used abolished locomotor activity. Atropine at a low dose (1 mg/kg, p.o.) increased and at a high dose decreased this parameter. Mazindol at a high dose also increased locomotor activity. A significant and dose-dependent increase in the time on the bar was observed in animals treated with carbachol or pimozide as compared to controls. The increase observed with pimozide was greater than 60 s. Effects of carbachol on locomotor activity were observed already after the first drug exposure, but the increased time on bar produced by this drug in the test of catalepsy was observed only after repeated exposure (7th day). The effect of the highest dose (10 mg/kg, p.o.) of atropine (decreased activity) as related to the lowest one was evident at the 7th day, but the increased locomotor activity seen at the low dose was detected already at the first day. There was a predominance of the effect of pimozide on the open field as well as on catalepsy after its association with each one of the three doses of carbachol. The association of atropine and mazindol did not seem to alter locomotor activity and catalepsy as related to each drug alone. Our results indicate that interactions between dopaminergic and cholinergic systems play an important role on behavior and motor functions.

Administration, Oral↗

PubMed1999

Early withdrawal from repeated cocaine administration upregulates muscarinic and dopaminergic D2-like receptors in rat neostriatum.

The present results show an increase in locomotor activity 24 h following repeated cocaine administration only with the higher dose (10 mg/kg, i.p., daily for 1 week) compared to controls (administered with saline). Binding assays were done and the ligands used were [3H]N-methylscopolamine ([3H]-NMS), [3H]-SCH 23390, and [3H]-spiroperidol to determine muscarinic (M1- and M2-like), D1 and D2 receptors, respectively. Scatchard analyses revealed alterations in Bmax not only for muscarinic, but also for D2-like receptors that were significantly increased. On the other hand, no alterations were detected on D1-like receptors densities and dissociation constant values. However, the Kd value was significantly increased for D2 receptors. The changes in muscarinic receptors were observed predominantly on M2-like, which presented an increase of 84% with the 10 mg/kg, i.p., dose only. On D2-like receptors, increases of 63 and 54% were demonstrated with the doses of 5 and 10 mg/kg, i.p.. The preferential effects of cocaine on muscarinic and D2-like receptors were also demonstrated in vitro where decreases in [3H]-NMS and [3H]-spiroperidol binding were observed. The results indicate that the effects of cocaine on muscarinic and dopaminergic postsynaptic receptors are functions of dose, duration of treatment, and time of drug withdrawal.

Animals↗

PubMed1994

Metabolic responses to cholecystectomy: open vs. laparoscopic approach.

Laparoscopic cholecystectomy is considered a minor surgical procedure. In a prospective, randomized study, we compared the metabolic responses to surgery in two groups of patients submitted to open or laparoscopic cholecystectomy. The aim of the study was to verify if the latter caused less metabolic changes. Blood samples were drawn before the operation (basal), 1 h and 2 h after skin incision, and on the first and second postoperative days. The following parameters were studied: cortisol, renin, and leukocytes, including subpopulations. The mean values for age, weight, height, basal neutrophil and lymphocyte counts, basal values of cortisol and renin of patients, and sex distribution of group 1 patients (open, n = 20) matched with those for group 2 (laparoscopic, n = 20), with the exception of age (p < 0.05). No differences were detected between the two groups in terms of cortisol and renin values. However, the neutrophil count 1 h after skin incision was statistically significantly higher with the laparoscopic approach (p < 0.05). The lymphocyte count on the second postoperative day was also statistically significantly higher in group 2 (p < 0.05). We conclude that when a cholecystectomy is performed, the laparoscopic approach has no advantage over the open approach from the standpoint of the metabolic responses we studied. It appears that leukocytes have a more rapid return to normal values after laparoscopic cholecystectomy. Although pneumoperitoneum is known to be responsible for important cardiorespiratory changes, no worse response was found in the laparoscopic group than in the open group.

Adult↗

PubMed1992

Effect of piracetam administration on 3H-N-methylscopolamine binding in cerebral cortex of young and old rats.

Piracetam, a nootropic drug, has been used for some time in Alzheimer's disease for its facilitatory effect on learning and memory. Rats treated with piracetam (500 mg/kg, p.o.) daily, during 1 and 2 weeks, showed a significant increase in muscarinic receptor number (Bmax) and in the dissociation constant values (Kd) in the cerebral motor cortex, in binding studies using 3H-NMS as ligand. The effect was observed not only in young rats (control- Bmax = 663.4 fmol/mg protein, Kd = 0.45 nM; treated- Bmax = 961.9 fmol/mg protein, Kd = 0.82 nM) but also in aged animals (control- Bmax = 628.0 fmol/mg protein, Kd = 0.47 nM; treated-Bmax = 747.6 fmol/mg protein, Kd = 0.84 nM). Since piracetam does not interact with muscarinic receptors, the reason for its effect expressed as the enhanced number of brain muscarinic receptors is not clear but could be the result of stimulation of phospholipid synthesis and thus would represent an indirect action of the drug.

Aging↗

PubMed1992

Effect of mazindol administration on (3H)-N-methylscopolamine binding to rat cerebral cortex.

Mazindol has been shown to produce anorexia in several animal species including humans, and its pharmacological effects may be elicited by blockade of neuronal reuptake of dopamine and norepinephrine. Chronic treatment of rats with mazindol (10 mg/kg daily, p.o.) caused an increase in muscarinic receptor density (Bmax = 874.7 femtomoles/mg protein) as compared to controls (Bmax = 629.1 femtomoles/mg protein) in the cerebral motor cortex. An increase in dissociation constant (Kd) values was also observed which changes from 0.57 nM (control) to 1.17 nM after mazindol treatment. The mechanism underlying the observed effect of mazindol on receptors could be related to processes involving other neurotransmitters which also regulate cholinergic activity in the CNS. However, the implications of the eventual dopaminergic control on muscarinic receptors in the cortex is still an open question.

Animals↗

PubMed1992

[Ileoanal pouch for the treatment of adenomatous polyposis and ulcerative colitis--clinical and functional results].

The results of the first 9 patients with proctocolectomy and ileal pouch operated on between 1983 and 1990 were analysed. This procedure was carried out in 8 patients with adenomatous polyposis. Three of these patients had an associated rectal cancer and one a degenerated sigmoid polyp. One patient had ulcerative colitis and was previously submitted to a colectomy related with perforated fulminant colitis. Three types of pouches were constructed: 3 S, 3 J and 3W, all with a temporary ileostomy. A circular stapler was used in 2 cases for ileoanal anastomosis. Three postoperative complications were observed: two patients with pouchitis during the presence of a diverting ileostomy and an ileal fistula following ileostomy closure, all medically treated. Clinical and functional results were evaluated 1 to 7 years after the procedure. The average daytime stool frequency was 4 with 1 nocturnal. All patients indicated normal continence. One patient had her professional life affected due to the increased number of defecations. Differences in the clinical results of the patients with S, J and W pouches were not statistically different. The functional results expressed as median and range were as follows: resting and pressure 45 cm H2O (20-60), voluntary anal pressure 70 cm H2O (34-120), compliance 3.70 ml/cm H2O (1.14-11.40), maximal tolerated volume (MTV) 320 ml (110-48) and threshold volume 95 ml (40-170). The MTV values of the groups with J and W pouches were 190 ml (180-200) and 370 ml (340-480), respectively (p = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMedDate not supplied

Gastric pseudotumor.

The authors present a case report of a pseudotumor of the stomach and a brief discussion about this very unusual entity. A 75-year-old female patient was admitted with melena and a large epigastric tumor; she underwent upper gastrointestinal endoscopy, abdominal ultrasound, magnetic resonance imaging, guided needle aspiration and angiography. Preoperative diagnostic hypothesis included a partially thrombosed aneurysm of the splenic artery, pancreatic cystic neoplasm with gastric invasion and pancreatic pseudocyst complicated with hemorrhage. Laparotomy revealed a gastric tumor and the patient was submitted to a radical subtotal Billroth II gastrectomy. Only the pathologic examination revealed the unexpected definitive diagnosis of an organized intramural gastric hematoma. There were no postoperative complications and she remains asymptomatic 10 months after surgery.

Aged↗