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Biomedical subjects

G A Olson

Publications and source records attributed to G A Olson.

At least 37 records · Page 2Linked to original sources
PubMed1986

Lesions in ventromedial hypothalamus or amygdala do not affect naloxone's suppression of water consumption.

Rats received lesions in the ventromedial hypothalamus (VMH) or amygdala, or were sham operated, and then were tested for two-hour intake of water after injections of naloxone (2 mg/kg), MIF-1 (2, 4, or 8 mg/kg), or diluent. There was a significant effect of test compound, with naloxone reducing consumption relative to the diluent control and the largest dose of MIF-1. Although MIF-1 tended to suppress drinking, the effect did not reach significance. There was no main effect for lesions, indicating that the amygdala and the VMH do not play a critical role in the effect of naloxone or MIF-1 on water consumption. A significant lesion by time interaction occurred, however, with amygdala-lesioned rats drinking the most in the first 30 min but much less after that. The VMH rats drank the most in the 30-60 min interval, but there were no differences in groups after 60 min. Thus, it appears that the intact VMH and basolateral amygdala are not necessary for naloxone's suppression of water consumption in the rat.

Amygdala↗
PubMed1985

Gastroduodenal ulceration in rabbits producing antibodies to prostaglandins.

The consistent occurrence of gastric and duodenal ulcers was observed in laboratory rabbits used for production of high-titer plasma antibody to 6-keto PGF1 alpha and PGE2. Perforations developed in 7 of 10 animals, usually just distal to the pyloroduodenal junction. The remaining rabbits showed gross and/or microscopic evidence of imperforate ulcers and erosions. These lesions appeared to be direct pathologic complications of an immune response directed against prostaglandins since animals immunized against met-enkephalin with similar methods had no ulcers.

6-Ketoprostaglandin F1 alpha↗
PubMed1985

Naloxone and fluid consumption in rats: dose-response relationships for 15 days.

Rats were given daily intraperitoneal injections of 10.0, 1.0, 0.1, 0.01, 0.001 or 0.0 mg/kg naloxone for 15 days. Each day after the injections, animals were allowed access to a 20% sucrose solution for two hours and to tap water for the subsequent 10 hours. Consumption of the sucrose solution by the group that received 1.0 mg/kg was reliably decreased on Day 1 and 2, reflecting the suppressive effect of naloxone at that dose. By Day 3 until the end of the experiment, however, the suppression was no longer significant, suggesting that tolerance had developed. A similar effect was seen with the group given the highest dose, 10.0 mg/kg; although drinking was significantly less than the control in each of the 15 sessions, this group showed a trend to increase intake over the days of the experiment, thus also indicating possible tolerance to the effect of naloxone. Drinking patterns of the other groups did not differ statistically from the control. Thus, the low doses had no ability to suppress consumption, and the lowest dose that did lower it soon lost that ability; the highest dose continued to suppress drinking throughout the study but with decreasing efficacy. High performance liquid chromatography (HPLC) demonstrated that the naloxone remained intact over the 15 days of the experiment, supporting the suggestion that tolerance to naloxone might have developed.

Animals↗
PubMed1984

MIF-1 (Pro-Leu-Gly-NH2) decreases activity in Siamese fighting fish (Betta splendens).

The effects of MIF-1 (Pro-Leu-Gly-NH2) on activity and aggression of male Siamese Fighting Fish ( Betta splendens) were considered. Animals were given intraperitoneal injections of 0.0 or 10.0 mg/kg MIF-1. After a 10-minute delay, they were placed in a 10 gallon aquarium and their activity was monitored for 60 minutes. Although aggressive responses in the presence of suitable opponents were not reliably affected, as significant decrease in general activity was produced. This is compatible with differential effects of MIF-1 across species.

Aggression↗
PubMed1983

Behavioral effects of melanocyte stimulating hormone release-inhibiting factor-1 (MIF-1).

Consideration of the isolation, structure, localization, and behavioral effects of melanocyte stimulating hormone release inhibiting factor (MIF-1) is followed by a review of its opiate antagonistic and clinical effects. Evidence pertaining to various hypotheses offered in explanation of these behavioral effects is examined and evaluated. It is concluded that MIF-1 affects behavior in many instances with possible antagonistic effects as well as clinical possibilities.

Animals↗
PubMed1982

Naloxone decreases consumption of liquid and solid sucrose in vagotomized rats.

Intraperitoneal injections of the opiate antagonist naloxone decreased food intake in both vagotomized and sham-vagotomized rats. Consumption of liquid and solid sucrose, which were used in order to equate baseline intake, was equally suppressed in both groups under food-deprivation and appetitively-motivated conditions at all doses of naloxone (1, 2, 4, and 8 mg/kg). It is concluded that, in contrast to previous findings, the vagus nerve does not mediate the suppressive effects of naloxone on feeding behavior.

Animals↗
PubMed1982

Effects of MIF-I, sex, and weight on tonic immobility in lizards (Anolis carolinensis).

Three experiments were done with the lizard, Anolis carolinensis, as a follow-up on our previous work which showed that MIF-I reduced tonic immobility (TI) during the breeding season and that females had longer TI durations than males in the non-breeding season. In June, during the breeding season, 60 male and 60 female lizards were injected with 0.1 mg/kg of MIF-I or naloxone or the diluent vehicle and placed in small aquaria for ten minutes. TI was then induced in the small aquaria. Similar experiments were conducted in September and October (non-breeding season). There was a reduction in TI durations in MIF-I and naloxone-treated lizards of both sexes in June, but the differences between drug treatment groups and controls were not significant. In September and October, MIF-I treatment resulted in TI durations similar to controls but naloxone treatment resulted in slightly shorter durations. Increased TI duration in females as compared to males was seen during both seasons, but diminished during the breeding season. Weight was found to be a factor in male lizards, with males greater than or equal to 4.0 g showing significantly longer TI durations. The lack of a significant effect of MIF-I on TI durations during the breeding season is possibly due to changes in the experimental design from the earlier report.

Animals↗
PubMed1982

Effects of naloxone and its quaternary form on fluid consumption in rats.

Three studies were performed on albino rats to determine the effects of naloxone and its quaternary derivative, naloxone methylbromide, on fluid consumption. The doses of the quaternary naloxone were equated with naloxone by molarity and effectiveness in order to facilitate direct comparisons. All rats were deprived of food and water for 12 hr and exposed to a 20% sucrose solution for a 2 hr period. In Experiment 1, a low (0.01 mg/kg) dose of naloxone or an equated dose of quaternary naloxone was given ICV and immediate access allowed to the fluid on four consecutive days. Animals receiving naloxone were not significantly different from controls, and rats receiving quaternary naloxone exhibited seizures, resulting in decreased consumption. In Experiment 2, the low dose of naloxone or the equated dose of quaternary naloxone was given IP for four consecutive days and neither was significantly different from controls. In Experiment 3, animals were given an IP dose of either 1 mg/kg naloxone, a 1 mg/kg or 50 mg/kg dose of quaternary naloxone, or saline and tested for a single 2 hr period. The doses of 1 mg/kg naloxone and 50 mg/kg quaternary naloxone produced significantly less drinking than controls. In all studies, the initial 30 min period produced the most drinking. Suppression of drinking by a dose of 50 mg/kg quaternary naloxone suggested, in contrast to other studies, that it may cross the blood-brain barrier at high doses.

Animals↗
PubMed1981

Tonic immobility produces hyperalgesia and antagonizes morphine analgesia.

Hyperalgesia was demonstrated during and immediately after termination of tonic immobility in the lizard Anolis carolinensis. Additionally, tonic immobility antagonized morphine-induced analgesia. In conjunction with other research, these data suggest that the response is accompanied by a reduced availability of serotonin, possibly at postsynaptic receptors of raphe neurons.

Analgesia↗
PubMed1981

Differential effects of neuropeptides on short-term memory in primates.

In a within-subject design, six rhesus monkeys (3 males and 3 females) received a 100 micrograms/kg injection of one of seven neuropeptides or a diluent control solution and were then tested for activity level, learning (discrimination reversal), short-term memory (delayed response), and for responsiveness to noxious stimuli. One daily injection was made with a different peptide for 10 consecutive days, including pre- and post tests on th first and last days with the diluent control. DSIP and D-Phe4-Met enkephalin seemed to produce some interference with short-term memory, while alpha-MSH showed some facilitation of it, as indicated by interactions of the peptides with the delay periods of 0, 15, or 30 sec. Sex differences were found in the learning task and the responsiveness to a noxious stimulus, suggesting the possibility of interactions between the peptides and endogenous hormones.

Animals↗
PubMed1981

Effects of MIF-I and sex differences on tonic immobility duration in the lizard, Anolis carolinensis.

In June, 36 lizards (males and females) were injected with 0.01, 0.1, 1.0, 10.0, or 100 mg/kg of MIF-I, or the diluent vehicle, and placed in a cage for ten minutes. Tonic immobility (TI) was then induced on an open lab table. All doses of MIF-I significantly reduced TI duration as compared to the duration with the diluent alone. In subsequent experiments lizards were injected with 0.1 mg/kg of MIF-I, 0.1 mg/kg of naloxone, or the diluent vehicle, and placed in small aquaria for ten minutes. TI was then induced in the small aquaria. In July, using 60 females, MIF-I and naloxone slightly reduced the duration of TI, but not significantly, and overall TI durations were reduced as compared with the first experiment possibly because the lizards could escape from the view of the experimenter in the corners of the aquaria. A third experiment was done in late September and early October with 120 males and 120 females. No drug effect was seen, but there was a significant difference between the TI durations of males and females, the females having longer durations. A relationship between the difference in response to MIF-I and the breeding seasons of the lizards could not be determined due to the possibility that the change in experimental design after the June experiments may alone have accounted for the loss of the significant response to MIF-I.

Animals↗
PubMed1981

Endogenous opiates: 1980.

Vast amounts of research have been done that have attempted to delineate the pharmacological and physiological effects of the endogenous opiate peptides. A great deal of knowledge has also been accumulated in a limited time span concerning the types and locations of the opiate receptors and peptides, as well as their functions. In 1980, reports were made concerning the effects of these peptides on analgesia, on tolerance and dependence, on activity, on learning and memory, on schizophrenia and other types of emotional disturbances, and on physiological responses such as eating and drinking, cardiovascular responses, and sexual function. Additional understanding was also gained concerning their interactions with neurotransmitters, other neuropeptides, and hormones. These and other studies published only in 1980 are reviewed in this paper, which is the third of an annual series.

Animals↗
PubMed1980

Effects of Pavlovian conditioning and MIF-I on the development of morphine tolerance in rats.

Thirty male Sprague-Dawley-derived rats were given daily IP injections of morphine (5.0 mg/kg) in the presence of a specific set of environmental cues for eleven consecutive days. Twelve hours after each morphine session, a control injection was given in a different environment. On Day 12 through 14 the environmental cues associated with each session were reversed. On Day 15 environmental cues associated with each session were the same as on Days 1-11. Analgesia was assessed by the tail-flick method 30 minutes after each morphine and control injection. Four independent groups (n=6) received either a lower (0.1 mg/kg) or a higher (5.0 mg/kg) dose of MIF-I either 10 minutes before or immediately after each morphine and control session. A control group received an injection of a diluent vehicle both before and after each session. None of these peptide-treatments significantly affected either acute action of morphine or the development of tolerance across days. Tail-flick latencies from both morphine and control sessions significantly decreased across days. On Day 12, when morphine was administered in the presence of cues not previously associated with its administration, tail-flick latencies were significantly longer than on the previous day. Tail-flick latencies did not change from Day 11 to Day 15 during control sessions. Morphine-session latencies did not change from Day 14 to Day 15, although they did decrease from Day 12 to Day 14. The significant morphine-induced analgesia on Day 15 of the experiment increases a remarkable resistance to the development of tolerance to morphine. The results partially support the hypothesis proposed by Siegel [115-18] that principles of Pavlovian conditioning exert an important influence on the development of tolerance to morphine.

Animals↗
PubMed1980

MIF-I suppresses deprivation-induced fluid consumption in rats.

Rats were injected IP with a 0.1 mg/kg dose of MIF-I, naloxone, dynorphin, [D-Phe4]-Met-enkephalin, [D-Ala2, F5Phe4]-Met-enkephalin-NH2, or the diluent vehicle, placed in their home cages for ten minutes, and then given ad lib access to either 20% sucrose, 10% sucrose, water, 0.01% quinine, or 0.02% quinine in a repeated measures design with solutions counter-balanced over five days. Fluid consumption was measured very hour for 4 hours. A mixed analysis of variance yielded significant results for all main effects and the peptides by fluid and hours by fluid interactions. For the 4-hr test period, naloxone and [D-Phe4]-Met-enkephalin produced reliable increased in consumption while MIF-I produced a reliable decrease. Differences were obtained only with sucrose solutions, and the results clearly suggest that peptides modulate fluid consumption at positive levels of incentive motivation. To reconcile the findings of increased consumption after naloxone with the many studies suggesting a decrease in such paradigms, 0.1, 1.0, and 10.0 mg/kg of naloxone and MIF-I were administered as before but to independent groups of rats and intake was measured every 30 min. These results replicate and extend the above findings by showing that during the first 30-min period, both naloxone and MIF-I suppressed intake in a dose-dependent fashion, with MIF-I being more effective at each dose. The 0.1 mg/kg naloxone group, however, increased consumption over time and achieved a total consumption greater than control animals but comparable to that observed in the first study. It appears that at very low doses naloxone increases consumption over time, but at more commonly tested higher doses it has a suppressant effect. The results support the concept that in many situations MIF-I can produce the same effects as naloxone.

Animals↗