Placental opioid-enhancing factor (POEF): generalizability of effects.

A substance in amniotic fluid and placenta (POEF for Placental Opioid-Enhancing Factor) has been shown to enhance opiate- or opioid-mediated analgesia in rats. Recent studies have only touched on the generalizability of the phenomenon. The present studies further tested the generalizability of the POEF effect: they examined sex specificity of the mechanism; whether POEF activity exists in afterbirth material of species other than the rat; whether POEF activity exists in tissue other than afterbirth material; whether POEF activity could be demonstrated after injection rather than ingestion of afterbirth material; and whether POEF enhances all opioid-mediated phenomena. We found that (a) POEF is effective in male rats as well as in female rats; (b) POEF activity exists in human and dolphin afterbirth material; (c) ingestion of pregnant-rat liver does not produce enhancement of opioid-mediated analgesia; (d) POEF does not seem to be effective when amniotic fluid is injected either IP or SC; and (e) POEF does not modify morphine-induced hyperthermia.

Glucose deprivation results in the induction of glucose-regulated proteins and domes in MDCK monolayers in hormonally defined serum-free medium.

Madin-Darby canine kidney (MDCK) cells spontaneously form dome-like structures in vitro, a phenomenon which has been proposed to be indicative of cellular differentiation. This study indicates the existence of a correlation between the induction of domes and of glucose-regulated proteins during glucose starvation. When MDCK monolayers were glucose deprived, domes appeared very rapidly. After only 3 h of glucose deprivation domes appeared in 69% of the microscope fields. The level of expression of glucose-regulated proteins (grps) as well as domes was examined over a 6-h time interval of glucose deprivation. Both grp 76 and 97 were induced over this time interval, with grp 76 being the more readily detectable. The level of induction of grp 76 as a function of time was quantitated by means of densitometry measurements. The induction of domes was examined in parallel with the induction of grp 76. The results indicated that the induction of grp 76 and domes occurs with a similar time course. The effect of glucose deprivation on the initial rate of ouabain-sensitive Rb+ uptake was also examined. Within the first 4 h of glucose deprivation, the initial rate of ouabain-sensitive Rb+ uptake did not differ significantly in glucose-deprived and control MDCK monolayers. These observations indicate that unlike the case with other methods of dome induction (e.g., treatment with either prostaglandin E1 (PGE1) or hexamethylene bis-acetamide (HMBA] glucose deprivation does not affect the Na+K+ ATPase activity of MDCK monolayers. These observations suggest that PGE1, HMBA, and glucose deprivation affect dome formation in MDCK monolayers by means of distinct mechanisms.