The objective of the present study was to evaluate the antinociceptive effects of phytol using chemical and thermal models of nociception in mice and to assess its antioxidant effects in vitro. Phytol was administered intraperitoneally (i.p.) to mice at doses of 25, 50, 100, and 200 mg/kg. In the acetic acid-induced writhing test, phytol significantly reduced the number of contortions compared to the control group (P < 0.001). In the formalin test, phytol reduced significantly the amount of time spent in paw licking in both phases (the neurogenic and inflammatory phases), this effect being more pronounced in the second phase (P < 0.001). Phytol also provoked a significant increase in latency in the hot plate test. These antinociceptive effects did not impaire the motor performance, as shown in the rotarod test. Phytol demonstrated a strong antioxidant effect in vitro in its capacity to remove hydroxyl radicals and nitric oxide as well as to prevent the formation of thiobarbituric acid reactive substances (TBARS). Taken as a whole, these results show the pronounced antinociceptive effects of phytol in the nociception models used, both through its central and peripheral actions, but also its antioxidant properties demonstrated in the in vitro methods used.

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Inflammation is characterized by vasodilatation, increase of blood flow and vascular permeability, migration of leucocytes to the inflammatory site, and production of cytokines. The aim of this study was evaluate the anti‐inflammatory and antinociceptive effects of (−)‐myrtenol, a plant‐derived monoterpene alcohol, in mice and its possible mechanisms. Myrtenol was used in classical models of inflammation (paw oedema induced by different agents, carrageenan‐induced peritonitis, myeloperoxidase levels and cytokine measurement) and nociception (acetic acid‐induced writhing, hot‐plate test, and paw licking induced by formalin, glutamate, and capsaicin). Pretreatment with myrtenol effectively inhibited paw oedema induced by carrageenan, compound 48/80, histamine, serotonin and prostaglandin E2. Myrtenol also reduced the cell counts, myeloperoxidase activity and cytokine levels (interleukin 1β, but not tumour necrosis factor‐α) of the peritoneal cavity induced by carrageenan. In addition, myrtenol inhibited acetic acid‐induced writhing, did not significantly prolong the latency time in the hot‐plate test, decreased licking time caused by an intraplantar injection of formalin (only in the second phase), glutamate and capsaicin. Myrtenol reduces the inflammatory response and nociception in mice due to the inhibition of the release of inflammatory mediators, cell migration and also to the signalling pathway of receptors involved in the transmission of pain. Copyright © 2014 John Wiley & Sons, Ltd.

Episodic memory was initially believed to be unique to humans. However, studies demonstrate that nonhuman species discriminate items based on the triad what, where and when. Here we addressed the role of the dorsal hippocampal subfield CA1 in an integrative what-where-when task in Wistar rats. We performed bilateral inactivation of dorsal CA1 with the GABA agonist muscimol previously to the task. As expected, sham-operated animals recollected an integrative memory for objects (what), their places (where) and temporal order (when). However, the inactivation of CA1 impaired the performance of the three components of episodic-like memory. In addition, total time of objects exploration and distance traveled were not different between groups, indicating that rats had similar levels of motivation, thus, alterations in exploration does not account for impaired locomotor performance. Altogether, our data provides evidence that CA1 plays an important role in episodic-like memory.

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