Effect of locus coeruleus and periventricular gray substance lesions on bright light-induced persistent estrous.

To assess the relation between the suprachiasmatic nucleus and the locus coeruleus, persistent estrous was induced in female rats by exposure to constant bright light followed with electrolytic damage of the locus coeruleus. Locus coeruleus lesions resulted in a transient loss of persistent estrous indicated by sustained diestrous aspect of the vaginal smears. There was a direct correlation between duration of estrous loss and the amount of locus coeruleus damage. Simultaneous damage to the periventricular gray substance adjacent to the locus coeruleus prevented the suppression effects of locus coeruleus damage upon persistent estrous. These results suggest a physiological role of the locus coeruleus and periventricular gray substance in the modulation of the neuroendocrine control of ovarian function due to suprachiasmatic nucleus activity.