S. Maswood et al., GENDER AND ESTROUS-CYCLE EFFECTS OF THE 5-HT1A AGONIST, 8-OH-DPAT, ONHYPOTHALAMIC SEROTONIN, Pharmacology, biochemistry and behavior, 51(4), 1995, pp. 807-813
Effects of the 5-HT1A agonist, 8-hydroxy-2-(di-n-propylamino)tetralin
(8-OH-DPAT; 0.04, 0.25, or 1.0 mg/kg), on hypothalamic serotonin (5-HT
), 5-hydroxyindoleacetic acid (5-HIAA), and their ratio were determine
d in adult male rats and in diestrous, proestrous, and estrous female
rats. Consistent with its action at the somatodendritic 5-HT1A autorec
eptor, 8-OH-DPAT decreased the 5-HIAA/5-HT ratio, but the decrease was
least evident in proestrous females and in males. Similar to hypothal
amic tissue, there was also a decline in the 5-HIAA/5-HT ratio in the
hippocampus after treatment with 0.25 mg/kg 8-OH-DPAT. When ovariectom
ized rats were treated with oil or estradiol benzoate followed 48 h la
ter by oil or progesterone, 0.25 mg/kg 8-OH-DPAT produced a decrease i
n the hypothalamic 5-HIAA/5-HT ratio in every group except those rats
treated with progesterone without estrogen priming. Treatment with est
radiol benzoate increased hypothalamic 5-HIAA, and both progesterone a
nd 8-OH-DPAT reduced the metabolite to the level of the ovariectomized
control. These results suggest that both estrogen and progesterone co
ntribute to an estrous cycle modulation of the 5-HT1A somatodendritic
autoreceptor.