Effects of zinc on the cytoskeletal proteins in the central nervous system of the rat

To test for in vivo zinc neurotoxicity on the cytoskeleton of neurotubules and intermediate filaments, Zn wires were implanted into the brains of adult Lewes rats for periods of 1–35 weeks. After 16 weeks of implant, some neurons showed bundles of intermediate filaments which were often localized in the perinuclear area. At the same time, occasional 200 nm tubular-like structures were seen in swollen dendrites. These structures were morphologically similar to Zn ion-induced aggregates of pure tubulin and structures found in ZnSO₄-treated dorsal root ganglion organotypic cultures. The 200 nm structures in dendrites and the intermediate filaments in neurons increased in frequency with time. After 35 weeks of Zn wire implant, few microtubules could be found in the lesion. All the animals showed an astrocyte and glial filament proliferation with axoglial membrane specialization. Other wires studied: Pt, Ni, Co, Mg, demonstrate that Zn wires have a specific effect on cytoskeletal proteins in the CNS of the rat and many of the effects can be explained by an interaction between Zn and tubulin.     

Delayed onset of experimental allergic neuritis in rats treated with reserpine

In delayed-type hypersensitivity most of the invading cells are not specifically sensitized against the initiating antigen but are augmenting cells called in by inflammatory mediators. It has been suggested that vasoactive amines, such as the monoamine serotonin, released by the action of sensitized T-cells on mast cells, may participate in the perivascular emigration of these cells that do not normally leave the blood. To test this hypothesis in experimental allergic neuritis (EAN), Lewis rats sensitized on day zero were treated with a single dose of the monoamine-depleting drug reserpine (2.5 mg/kg) immediately before the onset of early clinical signs on day nine (reserpine day 9, Rd9); during the onset of early clinical signs on day ten (Rd10); or immediately after the onset of early clinical signs on day 11 (Rd11). The results showed that the onset of early clinical signs was delayed in the Rd9 treated rats until approximately day thirteen whereas no effect on the course of the disease was observed in the Rd11 rats, and variable results were obtained in the Rd10 animals. Infiltration of mononuclear cells and leakage of 125I-albumin into the peripheral nerve was reduced in the Rd9 rats killed during the suppressed period. The delay in the onset of early clinical signs in the Rd9 rats correlated well with the time-course of serotonin depletion as reflected by levels in the peripheral blood of reserpine-treated normal animals. Although a role for histamine could not be demonstrated, the results suggest that other vasoactive amines are involved in the reaction. These results, therefore, would support the hypothesis that vasoactive amines play a role in the perivascular transit of inflammatory cells in EAN.     

Responses to the Assurance game in monkeys, apes, and humans using equivalent procedures

There is great interest in the evolution of economic behavior. In typical studies, species are asked to play one of a series of economic games, derived from game theory, and their responses are compared. The advantage of this approach is the relative level of consistency and control that emerges from the games themselves; however, in the typical experiment, procedures and conditions differ widely, particularly between humans and other species. Thus, in the current study, we investigated how three primate species, capuchin monkeys, chimpanzees, and humans, played the Assurance (or Stag Hunt) game using procedures that were, to the best of our ability, the same across species, particularly with respect to training and pretesting. Our goal was to determine what, if any, differences existed in the ways in which these species made decisions in this game. We hypothesized differences along phylogenetic lines, which we found. However, the species were more similar than might be expected. In particular, humans who played using "nonhuman primate-friendly" rules did not behave as is typical. Thus, we find evidence for similarity in decision-making processes across the order Primates. These results indicate that such comparative studies are possible and, moreover, that in any comparison rating species' relative abilities, extreme care must be taken in ensuring that one species does not have an advantage over the others due to methodological procedures.