Increased hexokinase activity in forebrain of water-deprived and diabetes insipidus rats

Metabolic studies using the 2-[14C]deoxy-D-glucose and cytochrome oxidase techniques have demonstrated changes in the activity of central sites associated with the hypothalamoneurohypophysial system in water-deprived (WD) and diabetes insipidus (DI) rats. Another method that may be used as an index of metabolic activity in discrete regions of the central nervous system is the measurement of hexokinase (HK) activity. This study describes changes in metabolic activity, as measured by HK histochemistry, in regions of the forebrain of WD and DI rats. Significant increases in HK activity measured by densitometric analysis were observed in the magnocellular component of the paraventricular nucleus of the hypothalamus, supraoptic nucleus, nucleus circularis, and neurohypophysis of WD and DI rats. In addition, increased HK activity was observed in the preoptic area and subfornical organ of DI rats. These data demonstrate that metabolic changes occur in the forebrain of WD and DI rats within structures involved in body fluid regulation. The present study also demonstrates that HK histochemistry may be used as a marker of metabolic activity in discrete regions of the central nervous system.