On the morphology of the Golgi apparatus and its relation to glucose-6-phosphate dehydrogenase in neurosecretory nuclei of rats under normal and thirsting conditions (application of karyometry)

Enzyme-histochemical studies on the nonsecretory neurons of the rat supraoptic nucleus with the application of karyometry and electronmicroscopy

Detailed histochemical studies were conducted on the distribution of SDH, G6PD, and TPPase as well as the Nissl substance and Gomori-positive material in the nonsecretory neurons of the supraoptic nucleus (SO) of the adult Wistar strain rats. Karyometry and statistical analysis were performed to identify those neurons. Electron microscopy confirmed the cytological characteristics indicated by the histochemical results. Based on the classification of SO neurons by the Golgi-Cox method and the present results concerning the Nissl pattern, shape, size, and number, these nonsecretory neurons appear to be intercalated neurons. Weak SDH and G6PD activity in the perikaryon with a few mitochondria indicate that they belong to the category of ordinary neurons with a low level of carbohydrate metabolism. The TPPase reaction revealed heterogeneous Golgi apparatus (GA) with poor development. In addition, it was difficult to find profiles of GA in many ultrathin sections. These results indicate that the GA may not undergo cyclic activity and lacks the capacity for secretion. No Gomori-positive material was detected in the perikaryon, whereas the Nissl substance was densely distributed throughout the entire perikaryon, where many free ribosomal rosettes and junctions of cisternae of abundant granular reticulum were evenly dispersed. The nonsecretory neurons reflect an active phase of cyclic activity of protein synthesis. However, other nonsecretory neurons with less active protein synthesis are very likely to be present.

Histochemical studies on the distribution of thiamine pyrophosphatase and enzymes related to carbohydrate metabolism in the intercalated neurons of the rat supraoptic nucleus

Histochemical studies have been conducted by applying hexokinase (HK), aldolase (AD), glyceraldehyde-3-phosphate dehydrogenase (G3), succinate dehydrogenase (SDH), glucose-6-phosphate dehydrogenase (G6PD), and thiamine pyrophosphatase (TPPase) methods, as well as Nissl staining and Gomori's chrome-alum-hematoxylin-phloxine (CHP) methods to intercalated neurons of the supraoptic nucleus (SO) on Wistar strain rats. Intercalated neurons reacted weakly to the AD, G3, G6PD, and SDH tests, indicating that they belong to the category of ordinary neurons with low carbohydrate metabolism. Many fibrous astrocytes showing strong HK reactions surround neurosecretory neurons. However, they do not surround intercalated neurons with mild HK activity. These results indicate that the latter receive a poor supply of energy from glucose in the circulating blood in contrast to the former. Intercalated neurons are very rich in Nissl substance but lack CHP-positive material. They may have a high potential for synthesizing protein. The principal morphological features of the TPPase-positive Golgi material are peculiar and heterogeneous shape and poor development. These findings together with mild G6PD activity suggest that intercalated neurons are very likely to have poor synthesizing activity.

Histochemical studies on the relationship between the morphology of the Golgi apparatus and G6PD activity in the locus coeruleus and dorsal vagal nucleus of the rat (application of karyometry)

Histochemical studies on the distribution of TPPase and G6PD in the neurons of locus coeruleus (LC) and dorsal vagal nucleus (DVN) of rats have been conducted by using the TPPase method, the G6PD method, karyometry, and statistics under normal conditions. 1. Neurons of the LC and DVN may undergo phasic changes of the GOLGI apparatus (GA) under normal condition. 2. No significant difference was found between neurons of the LC and DVN in regard to the GA morphology, but in general the latter revealed more complicated and developed GA than in the former. 3. Surprisingly, the G6PD activity of LC neurons was very weak. This is in agreement with the previous report by IIJIMA and IMAI (1975), and in disagreement with FRIEDE (1966). 4. An intimate parallel relationship was found between the GA morphology and G6PD activity in the DVN. The findings support the vigorous synthesizing activity found in the previous study of the rat supraoptic nucleus (IIJIMA 1979). In contrast to the DVN, such a parallel relationship between the Ga shape and G6PD activity was absent in the LC. Both findings strongly suggest that the role of the GA may be functionally different in the LC and DVN.