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K F Green

Publications and source records attributed to K F Green.

18 recordsLinked to original sources
PubMed1993

Early onset of reduced morphine analgesia by ingestion of sweet solutions.

Morphine analgesia can be reduced by prior exposure to food and flavored fluids. The early onset of reduced morphine-induced analgesia (RMA) was studied in 82 male Wistar rats after allowing them access to either a dextrose-saccharin solution or unflavored tap water for 6 or 3 h (Experiment 1, n = 40) or for 3 h, 90, or 45 min (Experiment 2, n = 42). Morphine (4 mg/kg) was injected subcutaneously at the end of the drinking period, and after 25 min a series of tail flick tests was conducted. Morphine produced strong analgesia in all rats that drank unflavored tap water; however, in rats that drank the flavored solution, the analgesic effect of morphine was significantly attenuated following exposures of 6 or 3 h, but not following exposures of 90 or 45 min. Similar quantities of flavored fluid were consumed by groups at all exposure durations; thus, RMA was determined by duration of exposure and not amount consumed. No analgesia attributable to flavor consumption per se was observed. The results suggest that RMA is mediated by endogenous opioid activity in the gustatory and analgesic systems by a mechanism akin to tolerance that requires about 3 h to operate.

Animals↗
PubMed1990

Is blockade of conditioned flavor aversions by chlorpheniramine the result of state dependency?

Conditioned flavor aversions induced by pairing flavored fluids with ionizing irradiation, lithium chloride, estrogen, or centrifugal rotation have been blocked by prior administration of chlorpheniramine. The blockade may be due to state dependency. This possibility was evaluated in the present experiment, which assigned female Long-Evans rats to a factorial combination of chlorpheniramine (20 mg/kg) vs saline during training, centrifugal rotation (150 rpm for 15 min) vs none as an UCS, and chlorpheniramine vs saline in testing. Rats conditioned with saline and rotation showed strong aversions when tested with either same or chlorpheniramine. Rats conditioned with chlorpheniramine and rotation showed no change during conditioning; when tested with saline they showed no aversion, and when tested with chlorpheniramine they showed no change from conditioning. Rats conditioned with either chlorpheniramine or saline and no rotation showed high fluid intake when tested with saline and reduced fluid intake when tested with chlorpheniramine. The results were interpreted as offering little support for state dependency.

Animals↗
PubMed1989

Effects of antihistamines on centrifugal rotation-induced analgesia and conditioned flavor aversions.

Centrifugal rotation induces short lasting analgesia, as shown in tail flick tests conducted immediately afterwards, and apparently induces visceral upset that can support aversions for flavors ingested immediately beforehand, as indicated in later preference tests. Two experiments were performed with antihistamines to determine whether the analgesic and visceral effects of rotation were attributable to separate neurochemical systems. In each experiment four groups of rats were defined by factorial combination of UCS (rotation at 150 rpm vs. no rotation) and Drug (antihistamine vs. saline). In Experiment 1 the H1 blocker chlorpheniramine (20 mg/kg, IP) was found to be ineffective against analgesia and to block conditioned flavor aversions (CFAs). In Experiment 2 the H2 blocker cimetidine (100 mg/kg, IP) was found to have a nearly significant attenuating effect on analgesia and to have no effect on CFAs. The data support the idea that analgesia and visceral upset are attributable to separate mechanisms, both of which are activated by the same manipulations.

Analgesia↗
PubMed1988

Tolerance to morphine analgesia from brief exposure to a palatable solution.

The onset of tolerance to morphine analgesia was studied in 34 female Wistar rats immediately after they drank a dextrose-saccharin cocktail or tap water for 6 or 24 hours. Tail flick tests conducted at the end of the drinking period showed no analgesia in cocktail or water groups. Morphine (3.5 mg/kg) was then injected subcutaneously, and after 20 min another series of tail flick tests was conducted. Morphine produced strong analgesia in rats that drank water, but only partial analgesia in rats that drank the cocktail. This reduction in morphine analgesia did not differ in comparisons between 6-hour and 24-hour cocktail groups. The results were interpreted as indicating that ingestion of the cocktail produced tolerance for morphine in the test of analgesia, and that such factors as novelty of flavor stimulation or stress from repeated testing were unlikely to yield the attenuation of analgesia that was observed. It was concluded that processes that produce tolerance become active in less than 6 hours.

Animals↗
PubMed1988

Effects of time of testing, stress level, and number of conditioning days on naloxone sensitivity of conditioned stress-induced analgesia in rats.

Controversy exists as to whether conditioned stress-induced analgesia (CSIA) utilizes opioid or nonopioid mechanisms. In two experiments, both an anticipatory conditioned stimulus (CS) and a shock-associated CS were used. The duration of exposure to the anticipatory CS was long, as in studies reporting opioid CSIA, whereas the duration of the shock-associated CS was short, as in studies reporting nonopioid CSIA. In addition, the effects of unconditioned stimulus (UCS) strength were investigated by using three levels of footshock (no, moderate, and high), and the development of CSIA was monitored by using different levels of training (1 to 6 days). CSIA, measured in both anticipatory and postexposure test periods, was found to be relatively stable across tail-flick trials within days and insensitive to strength of shock. As training progressed, CSIA increased with repeated CS-UCS pairings. We tested for opioid involvement using naloxone and found opioid and nonopioid mechanisms underlying CSIA; these mechanisms combined to form a stable level of analgesia. Our data suggest that stress level and amount of training interact to activate opioid and nonopioid mechanisms of CSIA. Apparent discrepancies in previous studies regarding naloxone sensitivity of CSIA may therefore be attributable to differences in stress levels, test periods and durations of exposure to shock-related cues.

Animals↗
PubMed1987

Effects of centrifugal rotation on analgesia and conditioned flavor aversions.

In the first experiment, 48 female Wistar rats were water deprived and given three conditioning days with saccharin-flavored water (1.5 g/liter) followed by 0, 5, 10 or 15 min of centrifugal rotation (150 rpm). Analgesia was measured by the tail flick test immediately after rotation. Over conditioning days, taste aversions developed. In general, taste aversion strength increased with duration of rotation. Analgesia also was in proportion to duration of rotation; however, over days tolerance developed in all rotated groups. In the second experiment 12 female Wistar rats were water deprived and given naloxone (20 mg/kg) or saline prior to 15 min of rotation. Rotation-induced analgesia was not affected by naloxone. It was concluded that somatic and gastrointestinal reactions to rotation are not served by a single mechanism.

Animals↗
PubMed1985

Effects of varicocele after unilateral orchiectomy and sympathectomy.

An experimental varicocele was created in the adult rat by partial ligation of the left renal vein. There was a significant bilateral elevation of both testicular blood flow and temperature in the varicocele animals (p less than 0.01). Mean testicular blood flow for control and varicocele animals was 29.6 +/- 1.0 and 39.8 +/- 2.0 ml./min./100 gm. tissue, while mean testicular temperature was 34.4 +/- 0.1 and 35.3 +/- 0.2C, respectively. A left orchiectomy was combined with a left varicocele to determine if the left testis is essential for the right testicular response to a varicocele. Elevation of right testicular blood flow was not altered by left orchiectomy (p less than 0.05); however, right testicular temperature was no longer significantly increased. Mean right testicular blood flow and temperature for this group was 39.0 +/- 1.5 ml./min./100 gm. tissue and 34.2 +/- 0.15C, respectively. A left sympathectomy was combined with a left varicocele to ascertain if the right testicular response to the left varicocele was mediated through a neural pathway. A significant bilateral increase in testicular blood flow was noted with a left sympathectomy alone, and thereby masked the ability to evaluate the right testicular response to the simultaneous left sympathectomy and varicocele. Elevation of right testicular blood flow in response to the left varicocele is independent of the presence of a left testis and any immune response it may stimulate. The role of the sympathetic nervous system as a mediator of the bilateral varicocele effect remains undetermined.

Animals↗
PubMed1984

Varicocele: reversal of the testicular blood flow and temperature effects by varicocele repair.

An experimental left varicocele was created in the adult rat by partial ligation of the left renal vein. A varicocele repair was performed by high ligation of the internal spermatic vein. Testicular blood flow and temperature changes were measured in control and sham animals, animals 30 days after establishment of varicocele and animals 30 days after varicocele repair. There was a statistically significant (p less than or equal to 0.01) bilateral elevation of testicular blood flow and temperature in the varicocele group compared to control and sham groups. Varicocele repair returned these blood flow and temperature values to normal. Average testicular blood flow for control, varicocele, sham varicocele and varicocele repair animals were 29.6 +/- 1, 39.8 +/- 2, 30.7 +/- 1 and 29.8 +/- 1 ml. per min. per 100 gm. tissue, respectively. Testicular temperatures averaged 34.4 +/- 0.1, 35.3 +/- 0.2, 34.4 +/- 0.1 and 34.5 +/- 0.1 degrees C, respectively. It is possible that the elevation in blood flow is associated with the elevation of intratesticular temperature, which is known to impair spermatogenesis. The data support a relationship between the varicocele and potential testicular damage.

Animals↗
PubMed1979

Hippocampal theta in rats under urethane: generators and phase relations.

Recordings were made from the directly visualized dorsal hippocampus of urethane-anesthetized rats with silver ball and tungsten microelectrodes. Theta of about 5 c/sec was elicited by reticular stimulation and was located in two broad strata in and subjacent to CA1. A superficial generator yielded 200-250 microV theta from the alveus, stratum oriens and stratum pyramidale; a null-theta and phase-reversal point was located in stratum radiatum; a deep generator yielded 300-500 microV theta in stratum lacunosum-moleculare of the hippocampus and distal stratum moleculare of the dentate gyrus, with maximum amplitude near the fissure. No theta was found in CA3. Cross-correlation analyses between generators yielded coefficients on the order of -0.80 while within a generator--especially the deep one--coefficients could reach +0.95. Phase analyses showed the two generators were about 180 degrees out of phase, with the deep generator leading. Septotemporal movement along the upper generator yielded no phase shifts; similar movement along the deep generator showed slight lead ing in septal portions. Subiculofimbrial movement in both generators showed a complex pattern of phase shifts: generally, subicular sites led fimbrial sites, but an inversion of 10 degrees-20 degrees occurred in the millimeter anterior to the center of the hippocampus. Anatomical, phase and other datal led to consideration of a possible retrohippocampal role in supplementing the well-known pacemaker in the medial septum.

Anesthesia, General↗
PubMed1977

Lamellar organisation in the rat hippocampus.

A series of experiments was conducted in the urethane anaesthetised rat to determine the organisation of some hippocampal pathways in this species, using stimulating and recording microelectrodes to elicit and record pupulation spikes. It was found that the mossy fibres, alvear fibres and perforant path were clearly arranged in a lamellar fashion. Lamellar organisation could not be demonstrated for the afferents in the stratum radiatum which include the Schaffer collaterals. It was concluded that hippocampal organisation in this species essentially resembles that in the rabbit and cat.

Animals↗
PubMed1971

Recuperation from illness: flavor enhancement for rats.

Rats were given a distinctive fluid (milk or grape) during recuperation from an injection of a noxious drug (apomorphine). Single-bottle tests conducted after treatment indicated elevated consumption of the fluid conditionally paired with recuperation. This positive "medicinal" effect is to some degree independent of initial preference, of novelty effects, and of aversive reactions to other substances paired with the onset of illness.

Animals↗