Evelyn D. Kapes

A rapid histological technique for localizing recording sites in single unit electrophysiological studies in vitro

Recording sites from single unit electrophysiological studies in vitro can be precisely localized by first marking the recording locus either by depositing Fast Green dye (for micropipette studies) or electrolytic lesioning (for metal electrode studies). The slices are then fixed in paraformaldehyde, placed in sucrose and attached to a coverslip by the surface tension of water. The slices are attached to a base brain in a cryostat so that the sections can be cut at the proper angle. The slices are then stained using a Nissl staining protocol. This procedure provides intact sections from small tissue slices with the recording locus clearly demarcated.

Metabolism of Coronary Vasculature in Euthyroid, Hyperthyroid and Recovering Hyperthyroid Rats: A Histochemical Study

Coronary arteries and arterioles from normal rats, from rats made hyperthyroid by administration of desiccated thyroid for 10 weeks, and from hyperthyroid rats which were then fed normal control diets for 10 weeks, were examined histochemically to determine the activity of key metabolic pathways. The primary aims of this study were to determine if the alterations in particular enzyme and substrate activities that occur in thyrotoxic rat myocardium, arteries and arterioles were reversible and would return to normal levels following cessation of the hyperthyroid state. Our results suggest that hyperthyroid rats, even after 10 weeks on the normal diet, still show some compromise in arteriolar aerobic metabolism in favor of anaerobic pathways, while coronary arteries still demonstrate little glucose-6-phosphate dehydrogenase activity. Myocardial metabolic activity approximates that of normal control animals by the end of the 10th week on the normal diet.

A Histochemical Study of the Coronary Vasculature in Euthyroid and Hyperthyroid Rats

Coronary arteries and arterioles in the left and right ventricles from normal and hyperthyroid rats were examined histochemically to determine and to compare their metabolic activities. The test animals were made hyperthyroid by administration of desiccated thyroid for 8-10 weeks. Using histochemical techniques, selected enzymes and components of key metabolic pathways were examined. These pathways included an evaluation of aerobic (oxidative phosphorylation, Krebs cycle and respiratory chain) and anaerobic metabolic capacity, hexose-monophosphate shunt activity, amounts of deoxyribonucleic and ribonucleic acids present and activity of beta-oxidation of fatty acids. Our results indicate that normal coronary arteriolar metabolism is predominantly aerobic. The findings also suggest a reduction in aerobic metabolism with an accompanying increase in anaerobic potential in the hyperthyroid coronary arterioles. Thus, during thyrotoxicosis, the coronary arterioles may partially shift from aerobic to anaerobic metabolism. Moreover, in both the normal and thyrotoxic rat heart, the coronary microvasculature appears quite stable with little cell proliferation. In contrast, both the control and hyperthyroid rat coronary arteries appear to utilize primarily anaerobic pathways, while the control and hyperthyroid myocardium seem highly dependent upon aerobic metabolism. The tremendous reduction in glucose-6-phosphate dehydrogenase activity in hyperthyroid, when compared to normal coronary arteries and some larger arterioles, implies a reduced capacity for nucleic acid and protein synthesis in the test animals.

Cytochemistry of the Blood Basophil of Bufo marinus

The morphology and cytochemistry of the blood basophil of Bufo marinus are characterized, and compared and contrasted to the basophil from several other amphibians and with the mammalian basophil. The basophil of B. marinus contains at least one type of mucopolysaccharide and an acid mu- copolysaccharide, possibly heparin, within the cytoplasmic granules. Several amino acids, but no histidine, and no lipid, occur in B. marinus basophils. Furthermore, these basophils appear devoid of hydrolytic enzymes, excepting nonspecific esterase. They do possess numerous oxidative enzymes, however, in the intergranular cytoplasm. The basophil of B. marinus is more similar cytochemically to the mammalian basophil than to the basophil of several previously studied amphibians. Considerable information regarding the morphology and cytochemistry of the mammalian blood basophil is available (Wetzel et al., 1967; Ackerman and Clark, 1971; Komiyama and Spicer, 1974; van El- ven et al., 1977). Ackerman (1963a) pre- sents an excellent review and comparison of basophil cytochemistry in several mam- malian species, including man; he also compares and contrasts the basophil with the mast cell. In contrast, although discov- ered over a century ago, the precise func- tions of the mammalian basophil remain obscure, despite its involvement to some extent in phagocytosis, allergic reactions, and delayed hypersensitivity (Stossel, 1977). Even less is known about the am- phibian basophil. Due to the fragility of the basophil, and its infrequency (1% or less) in the peripheral blood (factors which also hindered study of this cell in mam- mals) few data regarding the amphibian basophil are available. Caxton-Martins (1978) cytochemically examined the leu- kocytes in two West African anurans, Rana temporaris and Bufo regularis, but reported his findings as granulocytes, not differ- entiating among neutrophils, eosinophils, and basophils. In the newt, Notophthalmus viridescens, Cowden et al. (1964) demon- strated the presence of mucopolysaccha- ride and tyrosine in basophilic leukocytes and tissue mast cells.

Mesencephalic arteriolar and neuronal metabolic profiles from fresh and in vitro incubated tissue sections in the mouse: a histochemical approach

Neuronal perikarya and arterioles of slices of mouse midbrain were examined histochemically to determine their metabolic profiles. No differences in reactivities of key metabolic enzymes were observed between fresh 400-micron tissue sections and sections undergoing in vitro incubation for 4 h at 35 degrees C. Both neurons and arterioles appear capable of aerobic and anaerobic metabolism, while fatty acid utilization is limited. An operative hexose-monophosphate shunt occurs in midbrain neurons and arterioles. These data strongly suggest that electrophysiological and neurochemical studies using the in vitro preparation yield similar data to those obtained from fresh tissue.

A histochemical examination of the metabolic profiles of rat ventral tegmental area and substantia nigra arterioles.

To determine the metabolic profiles of arterioles of the rat ventral tegmental area and zona compacta and zona reticulata of the substantia nigra (SN), the distribution of selected enzymes, or by-products, of key metabolic pathways were examined histologically. Arterioles of all three regions expressed the enzymes required for aerobic and anaerobic metabolism. However, the relative abundance of the enzymes and byproducts suggests a lower metabolic capacity for the SN than the ventral tegmentum, while lipid catabolism in both regions appears non-operative. Moreover, the larger ventral tegmental arterioles possess a greater potential for nucleic acid and protein synthesis. Together, these results suggest the larger ventral tegmental arterioles possess a greater capacity for proliferation and repair.

Effects of Methamphetamine on Arterioles of Rat Caudate Nucleus and Midbrain

No differences in arteriolar metabolic profiles from rat caudate nucleus, ventral tegmental area or substantia nigra were observed between saline-control and methamphetamine HCl-treated (20 mg/kg, i.p. twice daily for 10 consecutive days) animals. Arterioles from the above regions of forebrain and midbrain are metabolically active vessels with a capacity for aerobic and anaerobic metabolism. These results suggest that a high dose of methamphetamine does not alter cerebral arteriolar metabolism in the areas examined.

A metabolic profile of the rat caudate microvasculature: a histochemical study.

Arterioles of the rat caudate nucleus were examined histochemically to determine their metabolic profile. These microvessels appear capable of aerobic and anaerobic metabolism with a potential for nucleic acid and protein synthesis. Little intramural lipid storage occurs and any fatty acids utilized are provided via the blood supply. Likewise, glycogen is not seen in the arteriolar wall and may be rapidly turned over as a substrate for anaerobic metabolism.