Effect of guanine derivatives on lordosis behavior in estrogen primed rats

The effect of systemic administration of guanosine, cGMP, dipalmitoyl (dp) cGMP, 5'GMP and 5'GDP on lordosis behavior was studied in ovariectomized, estradiol benzoate (EB) primed rats (4 micrograms/rat). EB per se induced only weak lordosis behavior. Free cGMP (2.0 mg/rat); dp cGMP (1.0, 2.0 and 4.0 mg/rat) and 5'GMP (2.0 and 4.0 mg/rat) induced significant lordosis behavior in ovariectomized, estrogen-primed rats. Dp cGMP and 5'GMP (2.0 mg/rat), also induced lordosis behavior in ovariectomized, adrenalectomized estrogen primed rats. Lordosis behavior elicited with 2.0 mg/rat dp cGMP was blocked with 8.0 mg/rat methyl-isobutylxanthine (MIX), a phosphodiesterase inhibitor, suggesting that dp cGMP stimulated lordosis through its conversion to 5'GMP. Results are interpreted in terms of the activation of adenylate cyclase-cAMP systems by guanine nucleotides.