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It is generally accepted that morphine exerts its analgesic effect by binding to specific opiate receptors in the brain and spinal cord. Since Hughes et al. isolated and identified two endogenous pentapeptides, Met- and Leu-enkephalin, from the brain and found that they acted as agonists at opiate receptors, alpha-, beta- and gamma-endorphins, larger(More)
The effects of pituitary adenylate cyclase activating polypeptides (PACAPs: PACAP27, PACAP38) on glutamate-induced neurotoxicity were examined using cultured retinal neurons obtained from 3- to 5-day old Wistar rats. Cell viability was evaluated by double staining with fluorescein diacetate and propidium iodide. Effects of PACAPs on the increase in(More)
We have shown previously that intracerebroventricular (icv) injection of naloxone (a non-selective opioid receptor antagonist) or naloxonazine (a selective μ1-opioid receptor antagonist) at the maintenance phase of hibernation arouses Syrian hamsters from hibernation. This study was designed to clarify the role of β-endorphin (an endogenous μ-opioid(More)
The effects of prostaglandin (PG) E2 on glutamate-induced cytotoxicity were examined using primary cultures of rat cortical neurons. The cell viability was significantly reduced when cultures were briefly exposed to either glutamate or N-methyl-D-aspartate (NMDA) then incubated with normal medium for 1 h. Similar cytotoxicity was observed with the brief(More)
We previously demonstrated that cultured rat dorsal root ganglion (DRG) cells respond to stimulation with interleukin-1 beta (IL-1 beta) by releasing substance P (SP), and this response is regulated via the cyclooxygenase (COX)-2 pathway. In this study, to ascertain the interaction between nitric oxide (NO) and prostaglandins in primary afferent neurons, we(More)
The central body temperature (T(b)) regulation system during hibernation was investigated in Syrian hamsters of either sex. Hibernation induced in Syrian hamsters by housing them in a cold room under short day-light/dark cycle was confirmed by marked reductions in the heart rate, T(b) and respiratory rate. The hibernation of hamsters was classified into (i)(More)
Hibernation in mammalians such as hamsters is a physiological state characterized by an extreme reduction of various functions such as body temperature and metabolism. Under such severe conditions, the central nervous system (CNS) activity is maintained at a functionally responsive level. Although hibernation is an interesting behavioral state, the(More)
The protective effects of cholecystokinin (CCK) against glutamate-induced cytotoxicity were examined using cultured neurons obtained from the rat cerebral cortex. Cell viability was significantly reduced when the cultures were briefly exposed to glutamate or N-methyl-D-aspartate (NMDA) and then incubated with normal medium for 60 min. A 60-min exposure to(More)
Experiments were carried out to determine whether noxious stimulation produced biochemical changes in noradrenergic neurons in the spinal cord of rats and whether morphine induced different biochemical effects in the presence and the absence of noxious stimuli. Noxious stimuli, but not stress, significantly increased the normetanephrine (NM) concentration(More)