This is a review of research aimed at elucidating how various opiate analgesia substrates in rat brain stem interact with one another to bring about opiate analgesia. The three substrates studied are the midbrain periaqueductal grey (PAG), the bulbar nucleus raphe magnus (RM), and the bulbar nucleus reticularis paragigantocellularis (PGC). The methods used in the reviewed studies are unique in ...

Introduction: 17β-estradiol modulates nociception by binding to estrogenic receptors and also by allosteric interaction with other membrane-bound receptors like glutamate and GABAA receptors. Beside its autonomic functions, paragigantocellularis lateralis (LPGi) nucleus is also involved in pain modulation. The aim of the current study was to investigate the role of the intracellular estrogen...

The effects of formalin as a peripheral noxious stimulus on the activity of lateral paragigantocellularis nucleus (LPGi) neurons were examined. Spontaneous activity ofLPGi neurons was recorded after confirmation of their responsiveness to acute pain, and thereafter formalin (50 µL, 2.5%) was injected in the contralateral hindpaw. The response of the LPGi neurons was monitored for 60 min. A...

In the present study, the effects of formalin as a peripheral noxious stimulus on spontaneously active units of the nucleus reticularis paragigantocellularis (PGi), a narrow region of the ventral pontine reticular formation, was examined in urethane anesthetized rats. Spontaneous discharge of the PGi neurons was variable, ranging from I to 37 spikes per second. Formalin as a chemical irrita...

The immunocytochemical distribution of [Leulenkephalin and an adrenal enkephalin precursor fragment (BAM-22P) immunoreactivity was investigated in the diencephalon and brainstem of rats pretreated with relatively high doses of colchicine (300-400 pgil0 pl intracerebroventricularly). The higher ranges of colchicine pretreatment allowed the visualization of extensive enkephalincontaining systems ...

  In the present study, the effect of contralateral and bilateral electrolytic lesions of the nucleus reticularis paragigantocellularis (PGi) on tonic pain was assessed in rats. Pain-related behavior was evaluated using the formalin test 7 days after the lesion was made. PGi lesions did not produce any marked changes in the early phase of the formalin test, but significantly increased pain sens...

As one of the most important diffused brain modulatory systems, the nucleus locus coeruleus (LC) receives most of its afferents from the nucleus paragigantocellularis (PGi) and plays a major role in the control of drug dependence and some emotional and exciting states. For detailed investigation of the effect of morphine on relationship between these two brain stem nuclei, the activity of the r...