Quantitative Lysosomal Enzyme Activity Changes in the Neural Lobe of the Rat Following Water Deprivation and Lactation

Abstract

—The activities of five lysosomal enzymes, acid phosphatase, β‐glucosidase, β‐glucuronidase, β‐galactosidase and N‐arylamidase (classified according to Marks (1970)) were measured by means of sensitive microchemical techniques in frozen‐dried rat neural lobe tissue after experimental and physiological stimulation of hormone release from the hypothalamo–neurohypophysial system i.e. water deprivation (3 and 6 days), delivery and lactation (10 days). During all conditions of stimulation increases of 29 to 106 per cent were measured for lysosomal enzyme activity, expressed as mmol/ng DNA/h. With histochemical staining methods the acid phosphatase activity appears to be mainly localized in the pituicytes, but it was impossible to visualize the microchemically measured acid phosphatase activity increase within the two main compartments of the neurohypophysis, i.e. axonal endings and the neurohypophysial glial cells, the pituicytes.

Adaptation of <i>Camelus dromedarius</i> pars nervosa of the hypophysis to winter and summer living conditions

“…So, pituicytes could play a phagocytic role, for example in the turnover of neurosecretory nerve fibers [25,27] and catecholamine ones [28]. In addition, the high concentration of lysosomal acid phosphatase in rat pituicytes following water deprivation and lactation [29,30] supports their strong phagocytic capacity [22]. And as described in rats [31], microglia may participate in this process.…”

Acid Phosphatase Activity in the Rat Neurohypophysis During Increased Levels of Gonadotrophic Hormones, in Diabetes Insipidus (Brattleboro Strain) and After Water Loading

“…The increased secretion of neurohypophyseal hormones during osmotic stress, parturition and lactation has consistently been found to be accompanied by an increased lysosomal enzyme activity (see In¬ troduction). This increased enzyme capacity in the neurohypophysis is believed to be involved in the removal of release residues particularly since lysosomal enzymes capable of digesting such materials were found to be activated (Boer 8c Jongkind 1974).…”

“…Mor¬ phological studies indicate that lysosomes may be involved in the digestion of these residues in the axonal endings (Whitaker 8c LaBella 1972) and in the neurohypophyseal glial cells, the pituicytes (Kurosumi et al 1964;Kurosumi 1971). Lysosomal enzyme activity was indeed found to increase in the neu¬ rohypophysis after stimulation of the hormone release by osmotic stimuli (Kobayashi et al 1962;Boer 8c Jongkind 1974), and during delivery and lacta¬ tion (Boer 8c Jongkind 1974).…”

Glycosidases vis-à-vis Lipid Metabolism in the Central Nervous System of the Hedgehog (<i>Paraechinus micropus</i>)

“…There is considerable controversy concerning the distribution of these glycosidases in the central nervous system of vertebrates. Some workers have reported both these enzymes exclusively in the lysosomes [Hayashi, 1964;Boer and Jongkind, 1974], while Arvy [1966] reported (3-glucuronidase only in the white matter when assayed by the technique of Seligman et al, [1954], When the same worker applied the Woohsmann and Hortroft [1964] technique, he obtained a reac tion in Purkinje cells. Studies from this labo ratory on the central nervous system of fishes [unpublished data], amphibia [Sood, 1978[Sood, , 1979, reptiles [Sood, 1980b] and mammals [Hafiza and Sood, 1980] also reveal strong activity of these glycosidases in the tracts, fibrous bundles and commissures.…”