Involvement of peripheral cannabinoid and opioid receptors in ß-caryophyllene-induced antinociception.

BACKGROUND: ß-caryophyllene (BCP) is a common constitute of the essential oils of numerous spice, food plants and major component in Cannabis. The present study investigated the contribution of peripheral cannabinoid (CB) and opioid systems in the antinociception produced by intraplantar (i.pl.) injection of BCP. The interaction between peripheral BCP and morphine was also examined. METHODS: The antinociceptive effect of i.pl. BCP was assayed by the capsaicin tests in mice. Antagonists for CB and opioid receptors, and antisera against ß-endorphin were injected peripherally prior to i.pl. injection of BCP. Morphine in combination with BCP was injected subcutaneously or intrathecally. RESULTS: The i.pl. injection of BCP dose-dependently attenuated capsaicin-induced nociceptive response. The antinociceptive effect produced by BCP was prevented by pretreatment with AM630, a selective CB2 receptor antagonist, but not by AM251, a selective CB1 receptor antagonist. Pretreatment with naloxone, an opioid receptor antagonist, and ß-funaltrexamine, a selective µ-opioid receptor antagonist, reversed the antinociceptive effect of BCP. Pretreatment with naloxone methiodide, a peripherally acting antagonist for opioid receptors and antisera against ß-endorphin, resulted in a significant antagonizing effect on BCP-induced antinociception. Morphine-induced antinociception was increased by a low dose of BCP. The increased effect of morphine in combination with BCP was antagonized significantly by pretreatment with naloxone. CONCLUSIONS: The present results demonstrate that antinociception produced by i.pl. BCP is mediated by activation of CB2 receptors, which stimulates the local release from keratinocytes of the endogenous opioid ß-endorphin. The combined injection of morphine and BCP may be an alternative in treating chemogenic pain.

Development of schematic face preference in macaque monkeys.

This study investigated schematic face preferences in infant macaque monkeys. We also examined the roles of whole and partial features in facial recognition and related developmental change. Sixteen infant monkeys, all less than two months old, were presented with two stimulus pairs. Pair A consisted of "face" and "parts," with the components representing facial parts (i.e. eyes, mouth, and nose). Pair B consisted of "configuration" and "linear," each including three black squares. In each pair, one of two stimuli represented a facial configuration, namely "face" and "configuration." Visual following responses toward each stimulus were analyzed. The results revealed an early preference for schematic faces in these nonhuman primates. Infants less than one month of age showed a preference only for a stimulus that contained only whole facial configuration (i.e. "configuration" in Pair B). One-month-old macaque infants showed a preference only for "face" but not for "configuration." This result means that their preference at that age was affected by both the shape of the components and the overall configuration. As the developmental change and the contribution of both facial features are similar to those in human infants, it may suggest that primates share common cognitive processes in early schematic face recognition.

Training squirrel monkeys (Saimiri sciureus) to deceive: acquisition and analysis of behavior toward cooperative and competitive trainers.

Three squirrel monkeys (Saimiri sciureus) learned to reach toward a container that covered food if a cooperative trainer rewarded such reaches by giving the food. A competitive trainer kept any food found, but wrong selections by this trainer were also rewarded. The monkeys initially reached toward the baited container indiscriminately, but gradually and with the aid of color-cued containers, all 3 reliably reached "honestly" and "deceptively" in the presence of the cooperative and competitive trainers, respectively. The monkeys did not appear to take the trainers' knowledge about the location of the food into account, and deception did not occur if food was placed under the normally unbaited container. With additional containers present, monkeys misled the competitive trainer into selecting the unbaited container farthest from the baited one. Although not indicative of mental attribution, the monkeys' behavior suggests awareness of the acquired communicative function of the reaching response.

Deterioration of mechanical properties of composite resins.

The deterioration of the mechanical properties of composite resins was examined. The bending strength and the stress relaxation rate for sixteen experimental composite resins with different filler shapes, particle sizes and filler contents immersed in distilled water for 0-60 days were measured. The bending strength of all of the composites decreased with the increase of the immersion time in water. The composites with a high filler content (65 vol%) showed a greater decreasing ratio of bending strength than those with low filler content (40 vol%). The stress relaxation rate also increased with and increase of immersion time. The phenomena may be caused by the hydrolytic degradation of the silane coupling agent (gamma-MPTMS).