PT  - JOURNAL ARTICLE
AU  - Jern, Patrick
AU  - Chen, Jinglu
AU  - Tuisku, Jouni
AU  - Saanijoki, Tiina
AU  - Hirvonen, Jussi
AU  - Lukkarinen, Lasse
AU  - Manninen, Sandra
AU  - Helin, Semi
AU  - Putkinen, Vesa
AU  - Nummenmaa, Lauri
TI  - Endogenous Opioid Release After Orgasm in Man: A Combined PET/Functional MRI Study
AID  - 10.2967/jnumed.123.265512
DP  - 2023 Jul 13
TA  - Journal of Nuclear Medicine
PG  - jnumed.123.265512
4099  - http://jnm.snmjournals.org/content/early/2023/07/13/jnumed.123.265512.short
4100  - http://jnm.snmjournals.org/content/early/2023/07/13/jnumed.123.265512.full
AB  - The endogenous μ-opioid receptor (MOR) system plays a key role in the mammalian reward circuit. Human and animal experiments suggest the involvement of MORs in human sexual pleasure, yet this hypothesis currently lacks in vivo support. Methods: We used PET with the radioligand [11C]carfentanil, which has high affinity for MORs, to quantify endogenous opioid release after orgasm in man. Participants were scanned once immediately after orgasm and once in a baseline state. Hemodynamic activity was measured with functional MRI during penile stimulation. Results: The PET data revealed significant opioid release in the hippocampus. Hemodynamic activity in the somatosensory and motor cortices and in the hippocampus and thalamus increased during penile stimulation, and thalamic activation was linearly dependent on self-reported sexual arousal. Conclusion: Our data show that endogenous opioidergic activation in the medial temporal lobe is centrally involved in sexual arousal, and this circuit may be implicated in orgasmic disorders.