RESUMO
Electrical stimulation in the vicinity of the cell bodies of the locus coeruleus (LC) has been shown to support self-stimulation behaviors in rats. In the present study, a Conditioned Place Test, sensitive to both rewarding and aversive qualities of brain stimulation, was employed to determine (a) whether rewarding locus coeruleus stimulation would result in place preferences and (b) if so, whether dopamine receptor antagonism would affect the development of such place preferences. Animals were pretreated with pimozide (0.0, 0.5 or 1.0 mg/kg) prior to exposure to two distinctive environments only one of which was paired with locus coeruleus stimulation. Rats that received vehicle injections prior to stimulation/place pairings developed strong preferences for the stimulation-paired environment while those animals pretreated with 0.5 mg/kg pimozide showed no reliable shift in preference from baseline performance. Additionally, animals injected with the 1.0 mg/kg dose of pimozide exhibited mild place aversions to the stimulation-paired environment. It is hypothesized that dopamine neurotransmission is important for the rewarding effects of locus coeruleus stimulation without which such stimulation appears to be aversive.
Assuntos
Condicionamento Clássico/efeitos dos fármacos , Locus Cerúleo/efeitos dos fármacos , Motivação , Pimozida/farmacologia , Receptores Dopaminérgicos/efeitos dos fármacos , Autoestimulação/efeitos dos fármacos , Meio Social , Animais , Mapeamento Encefálico , Relação Dose-Resposta a Droga , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
A group of 55 patients with insulin-dependent diabetes mellitus, aged from 8 to 40 years, was followed and compared to a group of controls, in view of detecting a possible relation between the presence of inframicrobial agents and diabetes pathogenesis. The investigations revealed, in patients, significantly higher positivity rate of antibodies against mumps (27% versus 16.3% in controls), parainfluenza type 1 (45.4% versus 29.1%) and Epstein-Barr (54.5% versus 10.9%) viruses, and Mycoplasma pneumoniae (43.6 versus 18.2%).
