Growth hormone and prolactin response to apomorphine in bipolar and unipolar depression.

Background: It has been suggested that patients with bipolar disorder may have an increased sensitivity to dopaminergic (DA) compounds. This was investigated by measuring growth hormone (GH) or prolactin (PRL) response to apomorphine (APO), a dopamine receptor agonist, in patients with bipolar depression, unipolar depression and control subjects.

Methods: Fourteen patients in an episode of bipolar depression (BP), 15 in an episode of unipolar depression (UP) and 19 age- and gender-matched control subjects (C) participated. The growth hormone (GH) and prolactin (PRL) responses to subcutaneous administration of 0.005 or 0.008 mg/kg APO were measured over 2 h.

Results: The rise in GH was greater with the higher APO dose. Both the GH rise and the PRL fall following APO were similar in BP, UP and C. Neither the GH or PRL responses in BP and UP were affected by successful treatment of the depressive episode.

Conclusion: Our findings do not indicate an altered sensitivity of DA neurones in the hypothalamic-pituitary system in either bipolar or unipolar depression.