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J B Becker

Publications and source records attributed to J B Becker.

At least 73 records · Page 4Linked to original sources
PubMed1985

Involvement of nigrostriatal dopamine neurons in the contraversive rotational behavior evoked by electrical stimulation of the lateral hypothalamus.

This experiment was conducted to determine if nigrostriatal dopamine (DA) neurons are necessary for the contraversive rotational behavior evoked by electrical stimulation in the lateral hypothalamus. Rats were tested daily for electrical stimulation-induced rotational behavior (ESRB) for 5 days, and then given an injection of 6-hydroxydopamine (6-OHDA) or saline into the ipsilateral substantia nigra. The nearly total depletion of striatal DA (greater than 96%) completely abolished contraversive ESRB and resulted in the appearance of ipsiversive ESRB. Partial DA depletion (less than 95%) had no effect on contraversive ESRB. In animals with a partial DA depletion subsequent treatment with a low dose of alpha-methyl-p-tyrosine (40 mg/kg) attenuated contraversive ESRB, while having no effect on control animals, or the ipsiversive turning in animals with greater than 96% DA depletion. We conclude that the nigrostriatal DA system is necessary for contraversive rotational behavior evoked by lateral hypothalamic stimulation, but that only a small percentage of DA fibers are required to maintain apparently 'normal' function--at least as indicated by contraversive ESRB.

Animals↗
PubMed1985

Sensitization of rotational behavior produced by a single exposure to cocaine.

In rats with a unilateral 6-OHDA lesion of the substantia nigra a single exposure to cocaine significantly enhanced the ipsiversive rotational behavior produced by a second injection given one week later. It is concluded that it is not necessary to repeatedly administer psychomotor stimulant drugs to produce long-lasting changes in brain and behavior.

Animals↗
PubMed1984

Striatal dopamine release stimulated by amphetamine or potassium: influence of ovarian hormones and the light-dark cycle.

The release of endogenous dopamine (DA) from rat striatal tissue was studied in an in vitro superfusion system following hormonal manipulations in vivo. Progesterone treatment in estrogen-primed ovariectomized female rats potentiated DA release stimulated either by amphetamine or potassium (K+). In addition, the amount of striatal DA released in response to K+-stimulation was influenced by the light-dark cycle. We conclude that striatal DA release is modulated by ovarian hormones, and suggest that ovarian hormone modulation of presynaptic striatal DA activity may contribute to well-known estrous cycle dependent variations in some non-reproductive behaviors.

Animals↗
PubMed1984

Sex differences in the effects of early experience on the development of behavioral and brain asymmetries in rats.

The influence of early experience (preweaning handling) on the development of several postural/motor asymmetries (side bias in an open field, turn preference in a T-maze, amphetamine-induced rotational behavior, tail pinch-induced asymmetries) and the lateralization of brain dopamine was studied in adult male and female rats. In many cases the adult patterns of behavioral and brain asymmetries were modified by early handling in a sexually dimorphic manner. In addition, the direction of postural/motor asymmetries was very much task-dependent, especially in females. We conclude that: early experience may modify the development of behavioral and brain asymmetries; sex differences in asymmetries are very common; early handling may affect males and females differently; and different measures of postural/motor asymmetries may reflect different and multiple brain asymmetries.

Animals↗
PubMed1984

A simple in vitro technique to measure the release of endogenous dopamine and dihydroxyphenylacetic acid from striatal tissue using high performance liquid chromatography with electrochemical detection.

An easily constructed, inexpensive and simple system is described for the superfusion of neural tissue. To characterize the system, the dynamics of endogenous dopamine and dihydroxyphenylacetic acid release from striatal tissue were studied before and after exposure to potassium, amphetamine or cocaine.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1983

Cortical control of claw cutting in the rat.

Claw cutting emerges as a behavior between Postnatal Day 30 and 50, and by Day 100 at least 80% of rats have cut their claws. Complete frontal ablation or total decortication at any age abolished claw cutting, but complete posterior neocortex removal did not. In adult rats, motor cortex ablations or hemidecortications abolished claw cutting, whereas the same lesions given to infant rats spared claw cutting. Neonatal telencephalic noradrenaline depletion had no effect on the development or incident of claw cutting. Loss of claw cutting appears to be due to loss of efficient biting and chewing rather than to an inability to orient or to groom. The sparing after infant ablations may be due to functional reorganization of tissue within, or adjacent to, the developing motor cortex. The study demonstrates that careful examination of features of the laboratory rat's appearance can provide useful clues about its behavioral competencies. Furthermore, abnormalities such as loss of claw cutting can serve as a useful diagnostic indication of specific kinds of brain damage.

Animals↗
PubMed1982

Long-term facilitation of amphetamine-induced rotational behavior and striatal dopamine release produced by a single exposure to amphetamine: sex differences.

Amphetamine (AMPH)-induced rotational behavior in non-lesioned rats and AMPH-stimulated dopamine (DA) release from striatal tissue fragments in vitro were used to study the long-term effects of a single injection of AMPH on activity in the mesostriatal DA system. A single injection of a low dose of AMPH (1.25 mg/kg) greatly enhanced the rotational behavior produced by a second injection of AMPH given 3-4 weeks later in intact female, ovariectomized female and castrated male rats. The effect of AMPH pretreatment in intact males differed from that in the other groups. When only 7-8 days separated the two test sessions both intact male and female rats showed sensitization of rotational behavior, but the magnitude of the change was greater in females. In addition, a single injection of 1.25 mg/kg of AMPH in vivo produced a long-lasting (3-5 weeks) enhancement of AMPH-stimulated DA release from striatal tissue in vitro. It is suggested that: (1) repeated injections of AMPH are not necessary to produce a long-lasting facilitation of behaviors mediated by the mesostriatal DA system; (2) gender and/or hormonal state influences the development of long-term changes in the mesostriatal DA system; and (3) changes in DA release from presynaptic terminals may contribute to the behavioral sensitization produced by stimulant drugs. The phenomena reported here may provide complementary in vitro and in vivo models for studying neuroplasticity in brain DA systems.

Animals↗
PubMed1982

Cortical noradrenaline depletion eliminates sparing of spatial learning after neonatal frontal cortex damage in the rat.

The possibility that cortical noradrenaline (NA) is necessary for the sparing of function that occurs after neonatal frontal cortex damage was examined. Spatial localization by rats with frontal cortex damage sustained neonatally was better than by rats with similar damage sustained as adults. The sparing was abolished in rats depleted of cortical noradrenaline by means of neonatal 6-hydroxydopamine (6-OHDA) administration. NA depletion alone did not affect spatial localization. These data are consistent with the notion that NA has some general function in maintaining some forms of plasticity in posterior cortex.

Animals↗
PubMed1982

Sex differences and estrous cycle variations in amphetamine-elicited rotational behavior.

The experiments reported here were designed to determine if there are sex- and/or estrus cycle-dependent differences in amphetamine (AMPH)-elicited rotational behavior in unlesioned rats. Whole brain or striatal levels of AMPH produced by systemic administration of the drug were also measured. At all doses tested (1.0-10.0 mg/kg) systemic administration of AMPH resulted in significantly higher brain levels of AMPH in females than in males. A systemic dose was then calculated which produced equivalent brain levels of AMPH in males and females. Even with equivalent brain levels of AMPH, males produced significantly fewer net rotations than females in estrus, diestrus 2, or proestrus. In female rats the brain levels of AMPH produced by systemic administration did not vary with the estrous cycle. However, the amount of AMPH-elicited rotational behavior did. On the day of estrus, female produced significantly more net rotations than they did 24 h later, on the day of diestrus 1. It is suggested that sex and estrous cycle dependent differences in rotational behavior may be due to the direct or indirect modulation of mesostriatal dopamine activity by gonadal steroid hormone.

Amphetamine↗
PubMed1982

Sex differences and estrous cycle dependent variation in rotational behavior elicited by electrical stimulation of the mesostriatal dopamine system.

In this study electrical stimulation-induced rotational behavior was used as a behavioral index of mesostriatal dopamine (DA) activity to investigate gender and hormonal influences on the DA system. In female rats we found estrous cycle related variations in electrical stimulation-induced rotational behavior. A constant electrical stimulus produced significantly more turning on the day of estrus, than it did 24 h later, on diestrus 1. Gonadectomy attenuated contraversive rotational behavior in female, but not male rats. In contrast, ovariectomy had no effect on the ipsiversive rotational behavior produced by stimulation of the reticular formation. This evidence supports the idea that endogenous changes in gonadal hormone levels influence the functional activity of the mesostriatal DA system in a sexually dimorphic manner.

Animals↗
PubMed1981

Gonadectomy attenuates turning behavior produced by electrical stimulation of the nigrostriatal dopamine system in female but not male rats.

Rotational behavior induced by electrical stimulation of ascending dopamine neurons is used as a behavioral model to investigate gender and hormonal influences on extra-hypothalamic dopamine systems. Steroid hormones influence the metabolism of many dopaminergic drugs, and therefore this approach avoids the complications inherent in drug-induced behavior models of dopamine activity. We found that gonadectomy of female, but not male, rats severely attenuates electrical stimulation-induced rotational behavior. This suggests that some female gonadal steroid hormone(s) may modulate the activity of ascending dopamine neurons, while male gonadal hormones do not.

Analysis of Variance↗
PubMed1981

Sex differences in the amphetamine stimulated release of catecholamines from rat striatal tissue in vitro.

Sex and estrous cycle-related differences in the amphetamine (AMT)-stimulated release (pg/mg/min) of catecholamines (CA) from rat striatal and mediobasal hypothalamus (MBH) fragments were measured in an in vitro perifusion system. In striatal tissue from intact males, AMT stimulated the release of both norepinephrine (NE) and dopamine (DA). The AMT-stimulated release of DA from striatal tissue obtained from intact females varied with the stage of the estrous cycle. This increase in DA release was lower in striatal tissue from proestrous females than from females in estrus (P less than 0.05) or diestrus 1 (P less than 0.01). The NE release stimulated by AMT was greater than basal release only on estrus and diestrus. 2. Following castration (CAST) or CAST plus 500 micrograms testosterone propionate (TP), daily for 4 days, striatal tissue fragments from male rats continued to release CA in response to AMT stimulation. In contrast, ovariectomy (OVX) severely attenuated the AMT-stimulated release of both CA. Treatment of OVX females with 5 micrograms estradiol benzoate (EB), daily for 4 days, or 1.2 mg progesterone (P) slightly increased the AMT-stimulated release of DA but not NE. Treatment of OVX females with 5 micrograms EB, daily for 4 days, plus 1.2 mg P completely restored the AMT-stimulated release of both CA. Interestingly, MBH fragments from intact or gonadectomized rats, with or without hormonal treatment, demonstrated a consistent AMT-stimulated release of DA regardless of the sex of the animal. The AMT-stimulated NE release from these MBH fragments was less consistent, but there was no significant differences between the groups. These results demonstrate that the AMT-stimulated release of DA from striatal tissue in vitro is sex, hormonal, and tissue dependent.

Animals↗
PubMedDate not supplied

Sex differences in amphetamine-elicited rotational behavior and the lateralization of striatal dopamine in rats.

Sex differences are described in both a lateralized behavior (amphetamine-elicited rotation) and in the lateralization of striatal dopamine (DA) content. Amphetamine (AMPH) elicited significantly more partial turns, total rotations and lateralized (net) rotations in female, than in male rats. The two sexes also differed in their pattern of net rotations over time. In females, but not males, the striatum containing higher DA levels after amphetamine was consistently found to be contralateral to the dominant direction of rotation observed in the first 5 min interval after AMPH. No relationship was found between rotational behavior and medial frontal cortex DA or norepinephrine. The results are discussed in reference to cerebral lateralization in humans, and to possible sex differences in the modulatory effects of gonadal steroid hormones on striatal function.

Animals↗
PubMedDate not supplied

Effects of nerve growth factor infusion on behavioral recovery and graft survival following intraventricular adrenal medulla grafts in the unilateral 6-hydroxydopamine lesioned rat.

NGF was infused into the lateral ventricle of rats with unilateral 6-OHDA lesions of the substantia nigra along with adrenal medulla or control grafts. Treatment effectiveness, as measured by amphetamine-induced turning behavior, indicated that there were no significant differences between treated and control groups in spite of the survival of tyrosine hydroxylase (TH) immunoreactive grafts. Furthermore, adrenal medulla graft survival was not dependent on NGF infusion. These results indicate that TH-positive graft survival is not correlated with behavioral recovery as assessed by amphetamine-induced turning. These results differ from studies which utilized apomorphine-induced turning as a measure of behavioral recovery. We propose that adrenal medulla graft survival alone is not sufficient to promote behavioral recovery in the 6-OHDA lesioned rat.

Adrenal Medulla↗
PubMedDate not supplied

Intranigral grafts of fetal ventral mesencephalic tissue in adult 6-hydroxydopamine-lesioned rats can induce behavioral recovery.

Intrastriatal grafts of fetal ventral mesencephalon in rats with unilateral 6-hydroxydopamine lesions can reduce and even reverse rotational behavior in response to direct and indirect dopamine agonists. These grafts can ameliorate deficits on simple spontaneous behaviors, but do not improve complex behaviors that require the skilled integration of the use of both paws. We report here that rats with grafts into the DA-depleted substantia nigra, that receive cyclosporine A, can experience recovery on spontaneous behaviors that mimic those observed in Parkinson's disease. Specific cyclosporine A treatment conditions can differentially affect whether intranigral grafts normalize paw use during initiation or termination of a movement sequence. These findings may have important implications for the treatment of Parkinson's disease.

Age Factors↗