Frequency distribution of TPH mRNA silver grains in neurons of the dorsal raphe of spayed (n = 3), E-treated (n = 4), and E+P-treated (n = 4) animals. The frequency distribution of the E- and E+P-treated animals is shifted to the right compared with spayed animals, indicating an increase in signal intensity in the steroid-treated groups. E- and E+P-treated groups also had more cells that were positive for TPH mRNA.