Pain modulatory network is influenced by sex and age in a healthy state and during osteoarthritis progression in rats.

Old age and female sex are risk factors for the development of osteoarthritis (OA) and chronic pain. We investigated the effects of sex and age on pain modulatory networks in a healthy state and during OA progression. We used functional MRI to determine the effects of sex and age on periaqueductal gray functional connectivity (PAG FC) in a healthy state (pre-OA) and during the early and late phases of monosodium iodoacetate-induced OA in rats.

Modeling Learning Patterns to Predict Placebo Analgesic Effects in Healthy and Chronic Orofacial Pain Participants.

Successfully predicting the susceptibility of individuals to placebo analgesics will aid in developing more effective pain medication and therapies, as well as aiding potential future clinical use of placebos. In pursuit of this goal, we analyzed healthy and chronic pain patients' patterns of responsiveness during conditioning rounds and their links to conditioned placebo analgesia and the mediating effect of expectation on those responses. We recruited 579 participants (380 healthy, 199 with temporomandibular disorder [TMD]) to participate in a laboratory placebo experiment.

Brain networks and endogenous pain inhibition are modulated by age and sex in healthy rats.

Endogenous pain inhibition is less efficient in chronic pain patients. Diffuse noxious inhibitory control (DNIC), a form of endogenous pain inhibition, is compromised in women and older people, making them more vulnerable to chronic pain. However, the underlying mechanisms remain unclear.

Neural and behavioral changes driven by observationally-induced hypoalgesia.

Observing successful pain treatment in others can induce anticipatory neural processes that, in turn, relieve pain. Previous studies have suggested that social learning and observation influence placebo hypoalgesia. Here, we used electroencephalography (EEG) to determine the neurophysiological changes associated with pain relief acquired through the observation.

Age and Sex Differences in Acute and Osteoarthritis-Like Pain Responses in Rats.

In this study, we investigated age and sex differences in acute and chronic pain in rats. Groups of young (3-6 months) and aged (20-24 months) male and female Fischer 344 rats were used to assess basal thermal and mechanical thresholds, capsaicin-induced acute nocifensive responses and c-Fos expression in the spinal cord, and monoiodoacetate (MIA)-induced knee osteoarthritis (OA)-like pain responses. There was a significant sex, but not age, effect on thermal threshold on the hindpaw and mechanical threshold on the knee joint.

In search of a rodent model of placebo analgesia in chronic orofacial neuropathic pain.

All treatments are given in a context, suggesting that conditioning cues may significantly influence therapeutic outcomes. We tested the hypothesis that context affects placebo analgesia in rodents. To produce neuropathic pain in rats, we performed chronic constriction injury of the infraorbital nerve.