in this study, the effects of acute and chronic lithium on nociception induced by formalin and its interactions with morphine-induced analgesia were studied in mice. formalin test was selected to study nociception. subcutaneous injection of different doses of morphine (1.5, 3 and 6 mg/kg) induced analgesia in a dose dependent manner in both phases of the formalin test. intraperitoneal administr...

Stress has been shown to affect brain activity and promote long-term changes in multiple neural systems. A variety of environmental and/or stressful stimuli have been shown to produce analgesia, a phenomenon often referred to as stress-induced analgesia (SIA). However, acute and chronic stresses also produce hyperalgesia in various behavioral tests. There are now several animal models in which ...

In the present study, we examined the effects of dopamine (DA) receptor antagonists infused into the nucleus accumbens septi (NAS) on analgesia induced by intra-ventral tegmental area (VTA) infusions of the substance P (SP) analog, DiMe-C7 or morphine and intra-NAS infusions of amphetamine. Rats received intra-NAS infusions of either the mixed DA receptor antagonist flupenthixol (1.5 or 3.0 mic...

We have previously reported that stress analgesia sensitive to and insensitive to opiate antagonists can be differentially produced in rats by varying the severity or temporal pattern of inescapable footshock. In these studies, we give further evidence for the opioid and non-opioid bases of these paradigms of stress analgesia. We find that naloxone-sensitive analgesia demonstrates tolerance wit...

transcutaneous electrical nerve stimulation (tens) is an analgesia inducing method with increasing applications in clinical procedures. in this study we tried to evaluate the role of the adrenergic system and its different adrenoceptor subtypes in tens-induced analgesia. two types of low and high frequency electrical stimuli were used in rats through needle electrodes, inserted at the base of t...

Opioid and non-opioid mechanisms of analgesia elicited by two kinds of footshock stress that differ only in temporal characteristics previously have been inferred on the basis of susceptibility to naloxone blockade. The present study sought further evidence on this point by comparing these two kinds of footshock analgesia for possible tolerance development and cross-tolerance with morphine. It ...

it has been shown that stress and chronic pain could prevent the development of tolerance to morphine analgesia, which appears to be related to the activation of hypothalamus–pitutitary–adrenal (hpa) axis, activation of neuroendocrine systems and changes in neurochemical levels. moreover, the involvement of nitric oxide (no) in the development of tolerance to morphine analgesia has been implica...