Impaired recognition memory and cognitive flexibility in the rat L5-L6 spinal nerve ligation model of neuropathic pain.

Background And Aims: Although neuropathic pain is known to negatively affect cognition, the neural mechanisms involved are poorly understood. Chronic pain is associated with changes in synaptic plasticity in the brain which may impact on cognitive functioning. The aim of this study was to model neuropathic pain in mid-aged rats using spinal nerve ligation (SNL).

Microinjection of 2-arachidonoyl glycerol into the rat ventral hippocampus differentially modulates contextually induced fear, depending on a persistent pain state.

The endogenous cannabinoid (endocannabinoid) system plays a key role in the modulation of aversive and nociceptive behaviour. The components of the endocannabinoid system are expressed throughout the hippocampus, a brain region implicated in both conditioned fear and pain. In light of evidence that pain can impact on the expression of fear-related behaviour, and vice versa, we hypothesised that exogenous administration of the endocannabinoid 2-arachidonoyl glycerol (2-AG) into the ventral hippocampus (vHip) would differentially regulate fear responding in the absence vs.

Behavioural, neurochemical and neuroendocrine effects of the endogenous β-carboline harmane in fear-conditioned rats.

The putative endogenous imidazoline binding site ligand harmane enhances neuronal activation in response to psychological stress and alters behaviour in animal models of anxiety and antidepressant efficacy. However, the neurobiological mechanisms underlying harmane's psychotropic effects are poorly understood. We investigated the effects of intraperitoneal injection of harmane (2.

Fear-induced suppression of nociceptive behaviour and activation of Akt signalling in the rat periaqueductal grey: role of fatty acid amide hydrolase.

The endocannabinoid system regulates nociception and aversion and mediates fear-conditioned analgesia (FCA). We investigated the effects of the fatty acid amide hydrolase (FAAH) inhibitor URB597, which inhibits the catabolism of the endocannabinoid anandamide and related N-acylethanolamines, on expression of FCA and fear and pain related behaviour per se in rats. We also examined associated alterations in the expression of the signal transduction molecule phospho-Akt in the periaqueductal grey (PAG) by immunoblotting.

A role for the ventral hippocampal endocannabinoid system in fear-conditioned analgesia and fear responding in the presence of nociceptive tone in rats.

The endogenous cannabinoid (endocannabinoid) system plays an important role in fear-conditioned analgesia (FCA) and expression and extinction of conditioned fear. The hippocampus has an established role in both pain and conditioned fear and is a substrate for endocannabinoid activity. This study aimed to investigate the role of the endocannabinoid system in the ventral hippocampus (vHip) in FCA and in fear responding in the presence of nociceptive tone.

Investigating the effects of distracting stimuli on nociceptive behaviour and associated alterations in brain monoamines in rats.

Distraction interventions are used clinically to relieve pain. Exposure to distracting stimuli causes withdrawal of attention from the painful stimulus and reduces perceived pain. However, the neurobiological mechanisms mediating distraction-induced analgesia are poorly understood due, in part, to a paucity of animal studies modelling this phenomenon.

Orexin expression and function: glucocorticoid manipulation, stress, and feeding studies.

We investigated the effects of glucocorticoid manipulation on orexin-A-induced feeding and prepro-orexin mRNA levels in the lateral hypothalamic area (LHA) of the rat brain. Adrenalectomy (ADX) reduced orexin-A-induced feeding over 4 h by about 60%, compared with shams, an effect that was reversed by corticosterone (CORT) replacement. ADX had no effect on prepro-orexin mRNA levels in the LHA in either the morning or the evening; however, message was up-regulated by CORT in the morning but not the evening.