Local cerebral glucose utilization in normal female rats: variations during the estrous cycle and comparison with males.

The quantitative 2-[14C]deoxyglucose autoradiographic method was used to study the fluctuations of energy metabolism in discrete brain regions of female rats during the estrous cycle. A consistent though statistically nonsignificant cyclic variation in average glucose utilization of the brain as a whole was observed. Highest levels of glucose utilization occurred during proestrus and metestrus, whereas lower rates were found during estrus and diestrus. Statistically significant fluctuations were found specifically in the hypothalamus and in some limbic structures. Rates of glucose utilization in the female rat brain were compared with rates in normal male rats. Statistically significant differences between males and females at any stage of the estrous cycle were confined mainly to hypothalamic areas known to be involved in the control of sexual behavior. Glucose utilization in males and females was not significantly different in most other cerebral structures.