Orexin-2 receptor antagonism in the cornu ammonis 1 region of hippocampus prevented the antinociceptive responses induced by chemical stimulation of the lateral hypothalamus in the animal model of persistent pain.

Orexins are excitatory neuropeptides, mainly produced by neurons located in the lateral hypothalamus, which project to many brain areas. The orexinergic system plays a fundamental role in arousal, sleep/wakefulness, feeding, energy homeostasis, motivation, reward, stress and pain modulation. As a prominent part of the limbic system, the hippocampus has been involved in formalin-induced nociception modulation.

Role of dorsal hippocampal orexin-1 receptors in modulation of antinociception induced by chemical stimulation of the lateral hypothalamus.

The Hippocampus has a role not only in nociception but also in modulation of pain perception. In addition, orexinergic neurons present in the lateral hypothalamus (LH) have a recognized role in pain modulation. The presence of orexinergic projections from the lateral hypothalamus (LH) to the dorsal hippocampal Cornu Ammonis 1 (CA1) region raises the question of whether pain modulatory role of LH is mediated through the CA1.