NMR relaxation rates and blood oxygenation level

A linear relationship between the proton relaxation rates and the fraction of deoxyhemoglobin of circulating whole blood (fHb) has been established in vitro at 4.7 T. These results have been interpreted on the basis of the additivity of relaxation rates. The slope of the lines of transverse relaxation rates (R2) versus fHb was found to increase with interpulse delay in Carr-Purcell Meiboom-Gill (CPMG) experiments. The Luz-Meiboom relation applied to this interpulse delay dependence of R2 suggests a two-site chemical exchange rather than a diffusion mechanism. The 1-ms water proton exchange time derived from these observations has been interpreted in terms of exchange between exchangeable protons close to the paramagnetic center of hemoglobin and protons of bulk water.

Intra-accumbens delta 1-opioid agonist, pC1-DPDPE, differentially affects patterns of locomotor activity

The effects of bilateral microinjections of a new potent and highly selective delta-opioid receptor agonist pCl-DPDPE (0.00, 0.1, 1.0, or 2.5 micrograms/side) were tested in rats for 60 min in activity monitors. The durations of horizontal movement time, rearing time, and stereotypy time were measured during six consecutive 10-min time blocks. The pCl-DPDPE resulted in short-lived biphasic effects of attenuation followed by potentiation for the three measures. These data in part replicate the behavioral effects of other delta-opioid receptor agonists.

DALDA (H-Tyr-D-Arg-Phe-Lys-NH2), a potent mu-opioid peptide agonist, affects various patterns of locomotor activities

The central effects of mu-opioid receptor agonist DALDA (ICV 0.00, 0.1, or 1.0 micrograms) were investigated in rats for 120 min on activity monitors. The durations in seconds of horizontal movement time, rearing time, and stereotypy time were measured during 12 consecutive 10-min time blocks. DALDA (ICV, 0.1 and 1.0 micrograms) resulted in biphasic effects, inhibition followed by activation for horizontal movement, rearing, and stereotypy times.

Ontogeny of biphasic locomotor effects of quinpirole

The effects of the dopamine D2/D3 receptor agonist quinpirole (LY171555) on locomotor activity were tested on rats of 10, 15, 20, 30, and 60 days of age. In two separate experiments, doses of 0 (vehicle), 0.02, 0.2, or 2.0 mg/kg quinpirole were injected SC into rats at each age, and their effects measured either for 2 h at 15-min intervals, or 30 min at 5-min intervals. At 10, 15, and 20 days of age, quinpirole significantly increased distance travelled in a dose-dependent manner. At 30 and 60 days of age, quinpirole significantly decreased distance travelled early in the session and increased it later. These results suggest that a dopamine autoreceptor begins to function between 20 and 30 days of age. Concomitant with the appearance of quinpirole-induced locomotor suppression early in the session, the amount of quinpirole-induced activation late in the session declined.

Biphasic effects of intraaccumbens mu-opioid peptide agonist DAMGO on locomotor activities

The effects of bilateral microinjections of mu-opioid receptor agonist DAMGO (0.00, 0.01, 0.1, or 1.0 microgram/side) were tested in rats for 120 min in activity monitors. The horizontal movement, rearing, and stereotypy times in seconds were measured during 12 consecutive 10-min time blocks. DAMGO (0.01, 0.1, and 1.0 microgram) resulted in biphasic effects, inhibition followed by activation for each of the three measures. These data replicate the behavioral effects of ICV DAMGO except that the duration of the behavioral effects were longer with Acb injections.

The effects of methionine-enkephalin and its related metabolites upon the duration of the dorsal immobility response in rats

The effects of SC injections of methionine-enkephalin (Met1-5-Enk) and its N-terminal and C-terminal fragments upon the duration of the dorsal immobility response (DIR) over a 60-min time course were investigated. Experiment 1 analyzed the effects of various dosages (0.00-100.0 micrograms/kg) on DIR resulting in a potentiation of the duration in a dose-time course function. The effects of various fragments of Met1-5-Enk (10.0 micrograms/kg) from the N-terminal in Experiment 2 and from the C-terminal in Experiment 3 on the DIR resulted in the potentiation of the duration with the Met2-5-Enk and Met1-3-Enk fragments. All other fragments were not significant. The results were discussed in reference to the processing and metabolism of Met1-5-Enk.

Dopamine D1 receptor family agonists, SK&F38393, SK&F77434, and SK&F82958, differentially affect locomotor activities in rats

Dopamine D1 receptor family agonists, 2,3,4,5,-tetrahydro-7,8-dihydroxy-1phenyl-1H-3-benzazepine (SK&F38393), 3-allyl-2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine (SK&F77434), and 3-allyl-6-chloro-2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazep ine (SK&F82958), were compared for their behavioral effects on horizontal movement time, rearing time, stereotypy time, and thigmotaxis time. All agonists resulted in biphasic effects with attenuation followed by potentiation (0.01-10.0 mg/kg, SC). While SK&F38393 did not potentiate horizontal movement and rearing times, and had minor effects on thigmotaxis, SK&F77434 and SK&F82958 potentiated horizontal movement and rearing behaviors and attenuated thigmotaxis. The results were discussed in terms of the binding characteristics and current receptor theory.

Behavioral effects of the mu-opioid peptide agonists DAMGO, DALDA, and PL017 on locomotor activities

The relative role of central mu-opioid receptor agonists Tyr-D-Ala-Gly-N-Methyl-Phe-Gly-ol (DAMGO), Tyr-D-Arg-Phe-Lys (DALDA), and Tyr-Pro-MePhe-D-Pro (PL017) (0.00, 0.01, 01, or 1.0 micrograms, ICV) on behavior was investigated in rats for 60 min in activity monitors. DAMGO (0.1 and 1.0 micrograms) and PL017 (1.0 micrograms) resulted in biphasic effects, inhibition followed by hyperactivity for linear locomotor, whereas the 0.01-micrograms dosage was associated with hyperactivity. On the other hand, DALDA (0.1 and 1.0 micrograms) suppressed locomotor activity over the 60-min session.

Differential effects of SCH 23390 on immobility behaviors in developing rats

The effects of a single injection of a dopamine D1 antagonist, SCH 23390, at doses of 0, 0.05, 0.1, and 0.2 mg/kg on three different kinds of immobility behavior were tested in rats of 10, 15, 20, and 30 days of age. Each animal was tested for the dorsal immobility response (DIR), vertical cling catalepsy, and bar catalepsy. A different pattern of results was found for each of the three immobility behaviors. SCH 23390 significantly increased the DIR at each age except 15 days; there was a progressive increase in effect from 10 to 20 to 30 days of age. At the lowest dose, drug-induced bar catalepsy peaked at 15 days of age and declined at 20 and 30 days of age. The effect of SCH 23390 on vertical cling catalepsy increased with age, plateauing at 20 days. Thus, the developmental pattern of immobility responses to this dopamine D1 antagonist differs with each behavior measured.

Effects of intraaccumbens dopamine agonist SK&F38393 and antagonist SCH23390 on locomotor activities in rats

The present study examined the effects of the dopamine D1 and D5 subtype receptors agonist, R(+)-1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol (SK&F38393), and antagonist, R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-ben zaz epine (SCH23390), on locomotor activities after bilateral microinjection into the nucleus accumbens (Acb). SK&F38393 (0.1-10.0 micrograms) significantly potentiated and SCH23390 (0.01-1.0 microgram) significantly attenuated locomotor activity as measured by horizontal distance in cm. The data were supportive of the hypothesis that dose-related locomotor activities induced by microinjections of SK&F38393 into the Acb are independently mediated by D1 and D5 subtype receptors.

Somatosensory pressure affects immobility and grasping reactions in bilateral labyrinthectomized rats

The effects of dorsal clip pressure and proprioceptive plate pressure to soles of the feet on tonic immobility; dorsal clip pressure on contact righting, horizontal bar, and vertical cling; forepaw and slope board grasp reactions were investigated in bilateral labyrinthectomized (BL) rats. Both dorsal and proprioceptive pressures potentiated the duration of tonic immobility in BL animals whereas only the dorsal pressure affected the controls. Dorsal pressure potentiated the duration of the horizontal bar, vertical cling, and slope board grasps in both the control and BL group. However, the behavioral patterns were different. The BL animals had weak grasp reactions and with the dorsal clip, emitted "head-back fall" during the vertical cling and slope board grasp conditions. The results were discussed in terms of the tactile and vestibular interactions and control on the postural mechanisms.

Behavioral effects of opioid peptide agonists DAMGO, DPDPE, and DAKLI on locomotor activities

The effects of the mu-selective agonist DAMGO (ICV doses of 0.00, 0.01, 0.1, or 1.0 micrograms), the delta-selective agonist DPDPE (ICV doses of 0.00, 0.1, 1.0, or 10.0 micrograms), and the kappa-selective agonist DAKLI (ICV doses of 0.00, 0.01, 0.1, or 1.0 micrograms) were tested in rats for 60 min in an activity monitor. The durations in seconds of linear locomotor time, rearing time, stereotypy time, and margin time (thigmotaxis) were measured during six 10-min time blocks. DAMGO (0.1 and 1.0 micrograms) resulted in biphasic effects, inhibition followed by hyperactivity for linear locomotor, rearing, and stereotypy times, and an inhibition of thigmotaxis. DPDPE (10.0 micrograms) was associated with monophasic potentiation of linear locomotor activity and mixed effects in stereotypy times. DAKLI did not effect horizontal, rearing, or margin times; only stereotypy times resulted in mixed effects of DAKLI. The differential behavioral profiles were discussed in reference to the three opioid receptor subtypes.

Biphasic effects of dopamine agonist N-0434 on locomotor behaviors in rats

The effects of a dopamine agonist, (+/-)-2-(N-penylethyl-N-propyl)amino-5- hydroxytetralin (N-0434) (SC doses of 0.00, 0.01, 0.1, and 1.0 mg/kg) were tested in rats for 120 min in an activity monitor. The durations in seconds of horizontal locomotor time, rearing time, stereotypy time, and margin time (thigmotaxis) were measured during 12 10-min time blocks. N-0434 (0.1 and 1.0 mg/kg) resulted in biphasic effects (initial inhibition followed by potentiation) of linear locomotor time and an attenuation of thigmotaxis. The 0.1- and 1.0-mg/kg doses initially suppressed rearing time but had mixed potentiation effects. The 0.01- to 1.0-mg/kg doses suppressed stereotypy time. The differential behavioral profiles were discussed in reference to the functions of dopamine receptors.

Behavioral effects of long-term administration of an anabolic steroid in intact and castrated male Wistar rats

Once a week, intact and castrated male Wistar rats were intramuscularly injected with a 0.2 ml suspension of either 0, 10, or 50 mg nandrolone decanoate in cottonseed oil, for 8 consecutive weeks. After the sixth injection, locomotor activity was measured in an open-field and the acquisition of lever press behavior was assessed in an autoshaping procedure. Subsequently, all subjects were exposed to four sessions of continuous reinforcement prior to one session in which the effects of steroid administration on extinction were assessed. Locomotor activity decreased for all groups of rats with continued exposure to the open-field, differences between groups were not observed. Rats treated with the highest dose of nandrolone decanoate spent more time in the margin of the open-field. There were no significant differences between groups on any of the learning measures. Long-term, high-dose steroid administration in conjunction with mild food deprivation inhibited growth in intact and castrated rats, while low dose administration affected body weight in intact rats only. Steroid administration resulted in heavier and enlarged kidneys and lighter testes as well. These results suggest that the administration of anabolic steroids not only produces observable physiological changes, but that it may also affect spontaneous behavior. The failure to find differences in learning indices may have been a function of the particular paradigms used in the present experiment.

Locomotor activity following intra-accumbens microinjections of dopamine D1 agonist SK&F 38393 in rats

The present study examined the effects of the dopamine D1 receptor subtypes agonist SK&F 38393 on locomotor activities after bilateral microinjection (0.00, 0.01, 0.1, 1.0, 10.0 micrograms) into the nucleus accumbens (Acb). The dose of 0.1 microgram elicited the highest response rate across measures of locomotion, rearing and stereotypy behavior. On the other hand, the largest dose of 10.0 micrograms was associated with significant increase in center time behaviors. The data were supportive of the hypothesis that dose-related locomotor activities elicited by microinjections of SK&F 38393 into the Acb are independently mediated by D1 receptors.

Intrastriatal injections of dynorphin A fragments potentiate the dorsal immobility response in rats

The effects of bilateral intrastriatal injections (2.0 micrograms/side) of Dynorphin A 1-17 (Dyn A 1-17) and Dynorphin A 1-8 (Dyn A 1-8) and their related nonopioid fragments upon the dorsal immobility response (DIR) over a 1-h time course were investigated. Dyn A 1-17 and Dyn A 2-17 potentiated the duration of the DIR 5 min postinjection, whereas Dyn A 1-8 and Dyn A 2-8 potentiated the DIR duration at each time point over the hour with their greatest effect at 15 min. An SC injection of 4 mg/kg naloxone 15 min prior to central injections blocked the potentiation of the DIR effects of Dyn A.

Effects of dopamine D1 antagonists SCH23390 and SK&F83566 on locomotor activities in rats

The effects of the dopamine D1 antagonists R-(+)-7-chloro-8-hydroxy-3-methyl-1phenyl-2,3,4,5-tetrahydro-1-H-3 -benzazapine (SCH23390) and (+-)-7-bromo-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1- H-3-benzazapine (SK&F83566) were tested for 2 h on linear locomotor, rearing, stereotypy, and margin times in an open field. Each of the antagonists attenuated the duration of linear locomotion, rearing, and stereotypy times in a dose- and time-dependent manner. The effectiveness of the antagonists was relatively brief and SCH23390 was more effective than SK&F83566 on each behavior. The two antagonists had differential effects on margin time.

Intracerebral haloperidol potentiates the dorsal immobility response in the rat

The effects of intracerebral microinjections of 4-[4-(4-chlorophenyl)-4-hydroxy-1-piperidinyl]-1-(4- fluorophenyl)-1-butanone (haloperidol) (1.0 microgram, 0.5 microliter) in five regions of the brain were tested on the duration of the dorsal immobility response (DIR) and the cling and bar catalepsy in the rat. The duration of the DIR was significantly potentiated (but not the cling and bar catalepsy) following 2-h postinjection of haloperidol in the caudate putamen, nucleus accumbens, and globus pallidus but not in the substantia nigra pars compacta or cortex. These data further expand the previous evidence of regional variations in dopamine to the effects upon inhibitory behaviors.

Differential effects of intrastriatal estradiol on the dorsal immobility response in male rats

The effects of implants of 17 beta-estradiol and cholesterol in four regions of the dorsal striatum were tested on the duration of the dorsal immobility response in gonadectomized male rats. The dorsal immobility response was significantly potentiated by 4-h implants of 17 beta-estradiol in the dorsomedial and dorsolateral regions of the dorsal striatum but not in the ventromedial and ventrolateral regions. These data further support the growing evidence that estradiol acts directly but differentially on the striatum to affect behaviors in the rat.

Potentiation of the dorsal immobility response following intrastriatal injections of enkephalins

The effects of bilateral intrastriatal injections (1.0 microgram/side) of leucine5- and methionine5-enkephalins and their related nonopiate fragments upon three measures of immobility over a time course were investigated. Both leucine5-enkephalin and des-Tyr1-leucine-enkephalin potentiated the duration of the dorsal immobility response (DIR) 15 min postinjection and over a 1-h time course. On the other hand, methionine5-enkephalin and des-Tyr1-methionine-enkephalin potentiated the duration of the DIR at 5 and 15 min. These enkephalins and their fragments had no effect upon vertical cling and bar catalepsy. In a second study, an SC injection of 4 mg/kg naloxone 15 min prior to the central injections blocked the potentiation of the DIR effects of the enkephalins.

Differential effects of dopamine D2 agonist quinpirole upon the dorsal immobility response in rats

The effects of various dose levels of systemically injected quinpirole upon the dorsal immobility response (DIR) over a time course was investigated in male rats. A low dose of quinpirole (0.01 mg/kg) significantly attenuated the duration of the DIR following the 10-min interval, whereas the highest dose (1.0 mg/kg) had a biphasic effect so that at the 10-min interval the duration of the DIR was significantly potentiated and at the 60-min interval the duration of the DIR was significantly attenuated. The intermediate dose (0.1 mg/kg) had intermediate behavioral effects. The data support the growing evidence that quinpirole has differential effects upon behavior over time as a function of the dose levels. The present data were discussed in reference to presynaptic and postsynaptic dopamine D2 receptor theory.

A limiting factor mediates the differential activation of promoters by the human progesterone receptor isoforms

The two transcription activation functions (TAFs) of the human progesterone receptor (hPR) have been characterized. TAF-1, located in the N-terminal region A/B, has been narrowed down to a 91-amino acid sequence, which is sufficient for transcription activation in chimeras with the GAL4 DNA binding domain. Both hPR TAF-1 and TAF-2 activate a minimal promoter in yeast. No autonomous TAF could be found in the N-terminal 164 amino acids (designated AB3) which are responsible for the differential activation of promoters by the hPR isoforms A and B. Reduction of the target gene promoter complexity did not alter this differential activation, indicating that AB3 does not require additional promoter-bound factors to exert its effect. Instead, the cell specificity of AB3 and its ability to squelch hPR-induced transcription suggest that this differential isoform activity is due to the effect of a limiting factor which binds to region AB3.

Effects of intracerebral quinpirole on locomotion in rats

The effects of the dopamine D2 receptor agonist quinpirole (LY 171555) on locomotor activity and margin time (thigmotaxis or wall-hugging) were measured for 2 h in rats injected either s.c. (vehicle, 0.02, 2.0 mg/kg) or directly into either the dorsal striatum or nucleus accumbens (vehicle, 0.1, 1.0, 10, 20 or 40 micrograms bilaterally in each site). In all groups, margin time decreased as drug dose increased. As in previous research, quinpirole given s.c. decreased locomotor activity at a low dose and had a biphasic effect on locomotor activity at the high dose. Both of these effects were also elicited by quinpirole injected directly into the dorsal striatum; 10 and 20 micrograms decreased locomotion immediately, while 40 micrograms led to both the immediate decrease and a later increase. In contrast, the lowest doses of quinpirole (0.1 and 1.0 microgram) injected into the nucleus accumbens led to an increase in locomotion from 20 to 60 min, while the higher doses led only to the early decrease. Thus, both the locomotor activating and inhibiting effects of quinpirole are found in both the nucleus accumbens and the dorsal striatum, but the differing dose-response relationships indicate that the mechanisms are not the same in these two brain regions.

The effects of bilateral and unilateral vibrissotomy on behavior within aquatic and terrestrial environments

Introducing an untreated rat to a novel environment typically results in thigmotaxis or wall-seeking behavior and the unilateral removal of the vibrissae induces an asymmetry in thigmotaxis. The present study investigated the effects of bilateral and unilateral removal of the vibrissae (vibrissotomy) upon the rat exhibiting thigmotaxis within aquatic and terrestrial environments. Unilateral vibrissotomy resulted in directional thigmotaxis asymmetry toward the intact vibrissae side within both environments. Within the aquatic environment, the unilateral vibrissotomy group swam a significantly longer distance than the other two groups. The data are discussed in terms of activation and sensory information.