Delta opioid receptors: reflexive,defensive and vocal effective responses in female rats

Ultrasonic vocalizations may be an expression of the affective pain response in laboratory animals. The present experiment compares the effects of morphine to the delta agonist, DPDPE (d-Pen²,d-Pen⁵ enkephalin) on a range of reflexive, behavioral and affective responses during an aggressive interaction. In experiment 1, naive female Long-Evans rats received morphine (0, 1, 3, 6, 10 µg ICV), or DPDPE (0, 30, 60, 100 µg ICV). In experiment 2, female rats were treated with naltrindole (1.0 mg/kg IP) 20 min before DPDPE (0, 60, 100 µg ICV). The following endpoints were measured: (1) latency to tail flick in response to heat stimuli; (2) high (33–65 kHz) and low (20–32 kHz) frequency ultrasonic and audible vocalizations; (3) defensive behavior; and (4) motoric activity. Following a brief exposure to attack, rats were threatened by the aggressor but protected from further attack by a large, wire mesh cage, thereby allowing for continued behavioral and vocal measurement without the risk of physical injury; video and audio recordings were made during the attack and then during a portion of the protected encounter (2 min). Morphine suppressed pain reactions varying in complexity from a spinal reflex, to an organized escape reaction, to an affective vocal response. The delta agonist, DPDPE, attenuated high frequency ultrasonic calling and tail flick responding. Defensive behaviors were also modulated by DPDPE at doses that had no effect on walking or rearing, indicating behavioral specificity. By contrast, doses of morphine that decreased defensive upright and escape also decreased motor activity. In female rats, morphine and DPDPE share a common profile of effects on a range of functional end-points, but DPDPE appears to modulate more selectively the reactions related to aversiveness without exerting sedative effects. These data demonstrate a possible physiological role for delta receptors in affective and defensive reactions.     

Use of human cumulus granulosa cells for in vitro screening of reproductive toxicants

We investigated the possibility that human granulosa cells from the cumulus mass obtained during human in vitro fertilization/embryo transfer (IVF/ET) might be useful for screening of potential reproductive toxicants in vitro. The cumulus granulosa cells detached from the zona pellucida after fertilization were allowed to spontaneously adhere to the incubation dish following transfer (removal) of the embryo. These cumulus cells survived in culture for at least four additional days, appeared on simple inspection to be morphologically normal luteinized granulosa cells, and produced large amounts of progesterone (P) over the culture interval. Production gradually declined during culture in the absence of human chorionic gonadotropin (hCG); however, inclusion of hCG (100 ng/mL) in the medium maintained P production at control (day 1) levels. Introduction of estrogenic agents previously shown to suppress P production in porcine or human culture systems using mural granulosa cells showed comparable effects in this human cumulus cell system. 17 beta-estradiol (10(-5) M), clomiphene citrate (10(-5) M), and o,p-DDT (10(-5)) significantly inhibited hCG-supported P production by human cumulus cells in vitro. This system has the advantages that (1) human cumulus granulosa cells are readily available from IVF/ET programs, (2) the techniques for maintaining the cells in culture are extremely simple, (3) a marker of highly differentiated granulosa cell function (P production) can be reliably measured, and (4) the cells respond predictably like other comparable granulosa cell systems. We conclude that human cumulus cells are a readily available and useful resource for in vitro screening of potential female reproductive toxicants.     

Macrophage and lymphocyte potentiation of syngeneic tumor cell and host fibroblast collagenolytic activity in rats

The collagenolytic responses of normal rat skin fibroblasts (NRS-F) and rat mammary MTLn3 tumor-derived fibroblasts (Ln3-F) were examined following exposure to rat macrophage (M phi-CM)- and lymphocyte (LYM-CM)-conditioned culture medium and/or tumor cell-conditioned medium. Alveolar, intratumoral, and peritoneal macrophages were prepared from mammary adenocarcinoma-bearing rats, as were the peritoneal lymphocytes. Incubation of the two fibroblast populations with LYM-CM produced a 10- and 7-fold stimulation of collagenolytic activity by NRS-F and Ln3-F cells, respectively. Similarly, exposure of NRS-F and Ln3-F fibroblasts to peritoneal M phi-CM produced a 7- and 4-fold increase in the expression of collagenolytic activity, respectively. Conditioned medium from MTLn2 tumor cells also stimulated the collagenolytic expression of both fibroblast populations. Incubation of tumor-associated Ln3-F or NRS-F fibroblasts with MTLn2 tumor cell-conditioned medium enhanced fibroblast collagenolytic activity approximately 20 and 17 times, respectively. When M phi-CM and LYM-CM were further "conditioned" by a subsequent incubation with MTLn2 tumor cells, each stimulated the expression of collagenolytic activity by both fibroblast populations and this was especially pronounced (120-fold increase) in the response of Ln3-F to LYM-CM further conditioned by MTLn2 tumor cells. The conditioned media derived from M phi, LYM, and MTLn2 tumor cells with or without trypsin activation contained low levels of interstitial-type collagenolytic activity which made no significant contribution to the collagenolytic activity of the stimulated fibroblasts. Some collagenase inhibitory activity, however, was detected in the M phi-CM, suggesting that the actual stimulation of collagenolysis by host fibroblasts is underestimated. We conclude that macrophages, lymphocytes, and tumor cells all have the potential to produce stimulatory factor(s) which enhance the collagenolytic activity of normal fibroblast populations. This study provides further evidence of the multifactorial control of collagenase production and supports the concept that host cell-tumor cell interactions can enhance the expression of collagenolytic enzymes.     

Behavioral assessment of the type A behavior pattern

The present study attempted to assess systematically a set of behavioral subcomponents associated with the Type A behavior pattern. Sixty middle-aged men underwent the structured interview (SI) and a repeated version of the SI after a four-month interval. A high degree of interrater reliability was established for a number of behavioral components including speed and volume of speech, motoric activity, expiratory sighs, response latency, interruptions, unevenness of speech, plosive words, and potential for hostility. In general, these behaviors were stable over the four-month interval, although they did not all distinguish Type As from Type Bs. Only four behaviors successfully discriminated Type As and Bs at both interview sessions: speed of speech, volume of speech, number of interruptions, and potential for hostility. The results are discussed in terms of how these behavioral subcomponents may contribute to increased risk of premature coronary disease.     

Marijuana withdrawal in humans: effects of oral THC or divalproex.

Abstinence following daily marijuana use can produce a withdrawal syndrome characterized by negative mood (eg irritability, anxiety, misery), muscle pain, chills, and decreased food intake. Two placebo-controlled, within-subject studies investigated the effects of a cannabinoid agonist, delta-9-tetrahydrocannabinol (THC: Study 1), and a mood stabilizer, divalproex (Study 2), on symptoms of marijuana withdrawal. Participants (n=7/study), who were not seeking treatment for their marijuana use, reported smoking 6-10 marijuana cigarettes/day, 6-7 days/week. Study 1 was a 15-day in-patient, 5-day outpatient, 15-day in-patient design. During the in-patient phases, participants took oral THC capsules (0, 10 mg) five times/day, 1 h prior to smoking marijuana (0.00, 3.04% THC). Active and placebo marijuana were smoked on in-patient days 1-8, while only placebo marijuana was smoked on days 9-14, that is, marijuana abstinence. Placebo THC was administered each day, except during one of the abstinence phases (days 9-14), when active THC was given. Mood, psychomotor task performance, food intake, and sleep were measured. Oral THC administered during marijuana abstinence decreased ratings of 'anxious', 'miserable', 'trouble sleeping', 'chills', and marijuana craving, and reversed large decreases in food intake as compared to placebo, while producing no intoxication. Study 2 was a 58-day, outpatient/in-patient design. Participants were maintained on each divalproex dose (0, 1500 mg/day) for 29 days each. Each maintenance condition began with a 14-day outpatient phase for medication induction or clearance and continued with a 15-day in-patient phase. Divalproex decreased marijuana craving during abstinence, yet increased ratings of 'anxious', 'irritable', 'bad effect', and 'tired.' Divalproex worsened performance on psychomotor tasks, and increased food intake regardless of marijuana condition. Thus, oral THC decreased marijuana craving and withdrawal symptoms at a dose that was subjectively indistinguishable from placebo. Divalproex worsened mood and cognitive performance during marijuana abstinence. These data suggest that oral THC, but not divalproex, may be useful in the treatment of marijuana dependence.     

Purification and chemical modifications of hemoglobin in developing hemoglobin based oxygen carriers

The efficacy of blood substitutes, as a whole, has been readily demonstrated, in animals as well as clinical studies. It is well known that stroma free hemoglobin (SF-Hb) is very toxic, due to effects on renal and coagulation functions and vascular tone. Several modifications have been made to the hemoglobin tetramer in an attempt to eliminate its toxicity. Conjugation, cross-linking, polymerization, and recombinant technology have all been used to reduce toxicity, while aiming to optimize the therapeutic value of hemoglobin based blood substitutes. The remaining issue seems to be the hypertensive response seen in many hemoglobin solutions. The cause of the hypertensive response, and hence what chemical modifications are suitable to alleviate it are still under debate.     

Effect of a selective dopamine D1 agonist (ABT-431) on smoked cocaine self-administration in humans

Rationale: Data in laboratory animals suggest that D₁ receptor agonists may have potential utility for the treatment of cocaine abuse. Objective: The effects of ABT-431, a selective agonist at the dopamine D₁ receptor, on the reinforcing, cardiovascular and subjective effects of cocaine were investigated in humans. Method: Nine experienced cocaine smokers (8M, 1F), participated in nine self-administration sessions while residing on an inpatient research unit: three doses of ABT-431 (0, 2, 4 mg IV) were each given in combination with three doses of smoked cocaine (0, 12, 50 mg). ABT-431 was intravenously administered over a 1-h period immediately prior to cocaine self-administration sessions. A six-trial choice procedure (cocaine versus $5 merchandise vouchers) was utilized, with sessions consisting of: (a) one sample trial, where participants received the cocaine dose available that day, and (b) five choice trials, where participants chose between the available cocaine dose and one merchandise voucher. Results: ABT-431 did not affect the number of times participants chose to smoke each dose of cocaine, but produced significant dose-dependent decreases in the subjective effects of cocaine, including ratings of “High,”“Stimulated,” dose liking, estimates of dose value, “Quality,” and “Potency.” Furthermore, there was a trend for ABT-431 (4 mg) to decrease cocaine craving. ABT-431 also increased heart rate, while decreasing systolic and diastolic pressure at each dose of cocaine. Conclusions: These data suggest that D₁ agonists may have potential utility for the treatment of cocaine abuse. Received: 18 August 1998/Final version: 16 October 1998     

Epidermal growth factor protects epithelial-derived cells from tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis by inhibiting cytochrome c release.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in combination with chemotherapeutic drugs induces a synergistic apoptotic response in cancer cells. TRAIL death receptors have also been implicated in chemotherapeutic drug-induced apoptosis. This has lead to TRAIL being proposed as a potential cancer treatment. In nude mice injected with human tumors, TRAIL reduces the size of these tumors without toxic side effects. We demonstrate that the epidermal growth factor (EGF) stimulation of human embryonic kidney cells HEK 293 and breast cancer cell line MDA MB 231 effectively protects these cells from TRAIL-induced apoptosis in a dose-dependent manner. This stimulation blocks apoptosis by inhibiting TRAIL-mediated cytochrome c release from the mitochondria and caspase 3-like activation. EGF survival response involves the activation of AKT. Expression of activated AKT was sufficient to block TRAIL-induced apoptosis, and kinase-inactive AKT expression blocked EGF-protective response. In contrast, inhibition of EGF stimulation of extracellular-regulated kinase (ERK) activity did not affect EGF protection. These findings indicate that EGF receptor activation provides a survival response against TRAIL-induced apoptosis by inhibiting mitochondrial cytochrome c release that is mediated by AKT activation in epithelial-derived cells.     

Murine peritoneal injury and de novo adhesion formation caused by oxidized-regenerated cellulose (Interceed [TC7]) but not expanded polytetrafluoroethylene (Gore-Tex Surgical Membrane).

STUDY OBJECTIVE: To evaluate the impact of the materials contained in the available adhesion prevention barriers on the peritoneum. STUDY DESIGN, SETTING, PATIENTS: A murine paradigm was used, placing oxidized-regenerated cellulose (Interceed [TC7]) and expanded polytetrafluoroethylene (PTFE; Gore-Tex Surgical Membrane) in the peritoneal cavity for intervals up to 14 days. INTERVENTIONS AND MAIN OUTCOME MEASURES: The appearance of the peritoneum on scanning and transmission electron microscopy and the presence of de novo adhesions were the end-points used. RESULTS: Oxidized-regenerated cellulose caused localized sloughing of the mesothelial cell layer and leukocyte infiltration of the deeper tissue leading to the formation of adhesions to the bowel and liver in 58% of the animals. The surface of the oxidized-regenerated cellulose-injured peritoneum healed in 5 to 7 days. Neither peritoneal injury nor adhesions were noted in sham-operated animals or animals with PTFE. CONCLUSIONS: Oxidized-regenerated cellulose but not PTFE has a localized injurious effect on the peritoneum of the mouse, resulting in de novo adhesions. The impact of the barrier material itself on normal peritoneum may be an important consideration in designing surgical barriers for the prevention of postoperative adhesions.