Post-synaptic changes and increased dopamine receptor sensitivity in hypothyroid rats.

Hypothyroid rats showed increased behavioral sensitivity to both selective and non-selective dopamine agonists. Ligand binding analysis revealed no differences in concentration or affinity of striatal dopamine receptor subtypes in hypothyroid rats. Measurement of striatal cAMP levels however, indicated that hypothyroid rats showed a greater increase in cAMP production in response to stimulation by dopamine. It is concluded that the changes in behavioural sensitivity observed may be associated with alterations in post-synaptic mechanisms.