Biomedical subjects

W B Stavinoha

Publications and source records attributed to W B Stavinoha.

57 records · Page 4Linked to original sources

PubMedDate not supplied

Effects of subchronic soman on avoidance-escape behavior and cholinesterase activities.

Male Sprague-Dawley rats were trained on a discriminated avoidance-escape task. They were administered subchronically saline, 12.7 micrograms/kg (0.125 LD50) soman, or 25.5 micrograms/kg (0.25 LD50) soman. Injections were given 5 days per week for 4 weeks. Injections were given subcutaneously immediately following the avoidance behavior test session. Soman produced a reduction in avoidance behavior efficiency in a dose dependent manner. When soman was discontinued, the rats recovered their pre-soman control baselines. Untrained rats given soman according to the same soman regimen were used to measure acetylcholine in brain and cholinesterase activities in brain, blood, and diaphragm. After 18 soman injections at 12.7 and 25.5 micrograms/kg acetylcholine was reduced significantly only in the amygdala. Blood cholinesterase was inhibited as much as 57% after 12.7 micrograms/kg soman and 74% after 25.5 micrograms/kg. Plasma cholinesterase was inhibited to 24% by the 12.7 micrograms/kg dose of soman and to 38% by the 25.5 micrograms/kg dose. Plasma cholinesterase recovered to control levels 11 days after cessation of soman, and whole blood cholinesterase recovered 25 days after cessation of the higher soman dose. Cholinesterase was inhibited significantly in the hippocampus and amygdala in a dose dependent manner. The cholinesterase activities appear to parallel the soman induced decrement in avoidance behavior and the subsequent recovery to control levels following withdrawal of soman.

Animals↗

PubMedDate not supplied

Pentylenetetrazole-induced changes in cerebral energy metabolism in Tupaia glis.

The convulsant pentylenetetrazole was administered to the lower primate, the tree shrew. Shortly after the onset of seizures, the animals were killed using a microwave device at 25 Kw and 915 MHz. The energy metabolites glycogen, glucose, ATP, and phosphocreatine were measured in five layers of the cerebral cortex and three layers of the cerebellum. Results showed that, as compared with controls, seizing animals had decreased energy metabolites selective to certain layers. Glucose was decreased in all cortical layers, but only in the granular layer of the cerebellum. Phosphocreatine was decreased in the outer small pyramidal layer and the polymorphous layer of the cortex but was unchanged in the cerebellum. ATP was decreased only in the outer small polymorphous layer of the cortex. These changes are consistent with the concept that selective changes may occur during seizures and that these changes are localized to layers that contain pyramidal cells. Examination of whole cortex may mask more subtle regional changes.

Adenosine Triphosphate↗

PubMedDate not supplied

Differences in acetylcholine but not choline in brain tissue fixed by freeze fixation or microwave heating.

Among the many rapidly metabolized compounds in the brain, acetylcholine is one of the most challenging to sample effectively due to its rapid synthesis, degradation and sequestration. To ascertain problems that invalidate sampling procedures two methods of tissue fixation, microwave heat inactivation and freeze fixation, were used for obtaining mice and rat brain samples, respectively. The data show that acetylcholine levels obtained by microwave fixation were much higher than those obtained by freeze fixation. Choline levels were not affected by the fixation method used. Microwave fixation results in more accurate assessment of acetylcholine levels than the freeze fixation method, even though the tissue fixation time was less than 1 s in both methods, because tissue integrity is maintained in the microwave fixation, but not during freeze fixation.

Acetylcholine↗