| Abstract: | The involvement of neurotransmitters in the inhibitory effect of suckling on plasma LH was investigated. The effect of suckling on the plasma LH levels was studied when the activity of the neurotransmitters, dopamine or serotonin was blocked. Ovariectomized rats, suckling six pups were used for the experiments. Three blood samples were collected from each rat. of the mothers. The first sample was obtained after continuous nursing The pups were then removed for 12 hours and a second sample was taken. The pups were put back with their respective mothers for 12 hours and the third sample was taken. Drugs were administered so that the specific effect of each neurotransmitter was blocked during the last 12 hour period of suckling. There was no significant effect on the suppressive effect of suckling on LH levels when dopamine activity was blocked. With the blockage of serotonin activity plasma LH levels failed to increase with pup removal. These results suggest that the neurotransmitter dopamine may not be involved but that serotonin may be involved in the effect of suckling on LH. |
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