Introduction: Patients with Parkinsons disease on pharmacological treatment frequently loose weight but regain weight after subthalamic nucleus deep brain stimulation (SNBS). This is, at least in part, due to an increase in resting energy expenditure (Perlemoine et al., Br J Nutrition 2005; 93). As SNBS electrodes are located close to the hypothalamic centre regulating food intake, we investigated whether ghrelin levels would vary with SNBS and/or L-DOPA treatment.
Methods: Two types of patients suffering from Parkinsons disease were investigated: patients with chronic L-DOPA treatment (n=12) and patients with SNBS associated to L-DOPA (n=12). They were investigated before & after receiving L-DOPA, and depending on the group with and without neurostimulation. Total fasting ghrelin was assayed in duplicate with an RIA kit. Paired t-tests were used to compared subjects within groups.
Results: When the patients were sorted according to their chronic treatment, L-DOPA had a significant acute effect on ghrelin levels neither in non-SNBS patients (936±393 vs 919±317 pg/ml) nor in SNBS patients off neurostimulation (880±155 vs 883±201 pg/ml) (P>0.05). L-DOPA had no significant acute effect on ghrelin levels when all patients were considered together (908±231 vs 901±260 pg/ml; P>0.05).
Neurostimulation itself did not elicit any modification of ghrelin levels in patients off L-DOPA (932±177 vs 880±155 pg/ml; P>0.05).
In SNBS patients on neurostimulation L-DOPA nearly achieved a significant effect (932±177 vs 879±178 pg/ml; P=0.05).
Conclusion: Total circulating ghrelin does not play an important role in the modification of weight homeostasis in patients treated for Parkinsons disease. This is in agreement with recent findings that although patients with hypothalamic damage (tumour) show impaired satiety, there is no change in circulating ghrelin concentrations in response to a test meal (Daousi et al. JCEM 2005 90:5025).