Neuronal maps of the frontal ganglion of the cockroach, Periplaneta americana, prepared by heavy metal iontophoresis.

Neurons in whole mount preparations of the frontal ganglion (FG) of the cockroach, Periplaneta americana, were mapped with the aid of cobalt chloride staining and silver intensification techniques. Eighty-six neurons were counted in the FG after staining with reduced methylene blue. The cell size ranged between 20 to 35 microns in diameter. Of the somata located in the FG, 44 were found to contribute their fibers to the nervus recurrens, 26 to the right frontal commissure, 28 to the left frontal commissure, and 6 to the nervus connectivus. In addition, a few neurons presumably from the tritocerebral region also contribute their fibers in the formation of nervus connectivus. The present study has helped delineate the neuronal connections of the FG with the brain and neuroendocrine system (corpora cardiaca and corpora allata). This information will be useful in facilitating the positioning of microelectrodes in our future electrophysiological experiments.

Tryptophan hydroxylase and 5-HTP-decarboxylase activity in cockroach brain and the effects of p-chlorophenylalanine and 3-hydroxybenzylhydrazine (NSD-1015).

The activities of two enzymes of the serotonin biosynthetic pathway, namely tryptophan hydroxylase (TPH) and 5-hydroxytryptophan-decarboxylase (5-HTP-D), were determined in the cockroach, Periplaneta americana, brain using radiometric techniques, significant levels of both enzymes were found. p-Chlorophenylalanine (PCPA) inhibited brain TPH activity strongly both in vitro and in vivo. In vitro, 10 mM PCPA reduced the TPH activity by 76% and in vivo either 15 micrograms/g or 30 micrograms/g of PCPA inhibited brain TPH activity by 80-85%. The activity of 5-HTP-D enzyme was inhibited significantly in vivo by 3-hydroxybenzylhydrazine, commonly known as NSD-1015. A recovery in the activity of 5-HTP-D enzyme was observed 12 h after 50 micrograms/g of NSD-1015 but 100 micrograms/g caused an inhibition lasting for the 24 h period studied.

Retardation of brain myelination by malnourishment and feeding low protein irradiated diet in rats.

The effect of feeding low protein diet, and the low protein irradiated diet on the deposition of myelin in the brains of rats over two generations showed that malnourishment lowered the CNP enzyme activity when compared to the normal (high protein) diet fed control rats during early postnatal period. Irradiated low protein diet, when fed within 21 days of irradiaton (15 Krads Gamma radiation, 60Co rays), produced still lower CNP enzyme activity. This also enhanced other effects of retarding the brain development, by lowering the protein and lipid contents of the brain during a period from the 4th to 25th day of postnatal development. This suggests the possibility that feeding irradiated low protein food to malnourished developing mammals could cause serious problems like mental retardation.