Defeat-induced Analgesia and the Conditioned Display of Submissive Postures and Escape in Strains of Mice

Long-term analgesic reaction in attacked mice.

“…Reasoning in the same line, the second experiment was designed to establish differences in analgesia levels by pharmacological manipulations, whereas stress intensity (i.e., 50 bites) was kept constant. Because on the one hand social conflict analgesia, induced by high number of bites, can be influenced by opioid antagonists (Miczek et al, 1982; Rodgers & Hendrie, 1983; Rodgers & Randall, 1985; Siegfried, Frischknecht, Külling, & Waser, 1986; Teskey et al, 1984) and, on the other hand, the LTA reaction of rats is reduced when naltrexone is administered before the 80 inescapable tailshocks (Maier et al, 1980), we presumed that injections of opioid antagonists before the stress of 50 bites should prevent the LTA reaction. The opioid antagonists that we chose were naloxone, a short-acting antagonist, and beta-chlornaltrexamine, known for its long-acting potency by irreversible binding to opioid receptors (Frischknecht, Siegfried, Riggio, & Waser, 1983; Portoghese, Larson, Jiang, Caruso, & Takemori, 1979).…”

“…For instance, brief exposure to attack elicits a low-intensity, naloxone-insensitive analgesia that dissipates within 10 min (Rodgers & Randall, 1986; Siegfried, Frischknecht, Riggio, & Waser, 1987) and does not show cross-tolerance to or from morphine (Rodgers & Randall, 1986). In contrast, a prolonged exposure to attack induces a long-lasting analgesia that can be reversed by opioid antagonists (Miczek et al, 1982; Miczek, Thompson, & Shuster, 1985; Rodgers & Hendrie, 1983; Rodgers & Randall, 1985; Siegfried, Frischknecht, Külling, & Waser, 1986; Teskey et al, 1984), displays full cross-tolerance with morphine (Miczek et al, 1982; Rodgers & Randall, 1985), and is accompanied by changes in the endogenous opioid systems (Miczek & Thompson, 1984; Raab, Seizinger, & Herz, 1985).…”

“…On the basis of these data, we presumed that DBA mice, known to exhibit a strong opioid analgesia after exposure to prolonged attacks (Miczek & Thompson, 1984; Rodgers & Randall, 1985; Siegfried et al, 1984, 1986), would display a long-term analgesic reaction when reexposed 24 hr later to a small number of bites from a conspecific resident. Our experiments were designed to test this hypothesis and, as the hypothesis was confirmed, to characterize a social-conflict-induced long-term analgesic reaction.…”