PubMed Health⌕ Search

Biomedical subjects

P Ropartz

Publications and source records attributed to P Ropartz.

At least 19 recordsLinked to original sources
PubMed1994

Pituitary grafts and behavior in mice. Effects of sex of donor and number of pituitary grafts on exploratory and learning abilities.

The effects of ectopic pituitary grafts, sex of pituitary donor, and number of isografts (one or two) were examined in intact phenotypically normal male mice of the Snell dwarf strain, using a battery of tests designed to assess exploration and learning-related behavioral processes. Results show that neither sex of pituitary donor nor number of grafts affected behavioral responses to pituitary grafts. Ectopic pituitary grafts increased the level of exploratory activities assessed in a novelty preference test and in the hole board test, facilitated the retention of a step-through type passive avoidance task--contrasting with results in rats--but did not affect spatial orientation in a spontaneous alternation and a water escape task. The results argue for a global effect of the graft, inducing increased emotional reactivity.

Animals↗
PubMed1992

Prolactin similar to ectopic pituitary isograft restores responsiveness in Snell dwarf mice.

The effects of ovine prolactin (PRL) (2 x 5 IU a day) and an ectopic pituitary isograft on the responsiveness were examined using locomotor and exploratory activities as measures in PRL-growth-hormone-thyrotropin-deficient Snell dwarf mice (dw/dw). After 5 weeks of treatment, both PRL and the graft restored the two behavioural measures to normal levels. Results clearly demonstrate the involvement of PRL in global behavioural responsiveness and suggest a possible role for PRL in the changes induced by the graft.

Animals↗
PubMed1990

Effect of age at the time of pituitary grafting on behavioral recovery in dwarf mice.

The effects of ectopic pituitary isograft implanted in 13- or 21-day-old Snell dwarf mice on their freely expressed behavior were examined over a 14- or 31-day period. This mutant strain has severe anterohypophyseal deficiency which causes high levels of inactivity and abnormally low exploratory activity. The graft totally normalized these behaviors. Results showed that the time necessary for inducing behavioral changes is independent of age of the animals at the time of grafting, but the age at which implantation occurs influences the speed of full behavioral normalization. The possible involvement of prolactin and growth hormone in such behavioral improvement is discussed.

Aging↗
PubMed1986

Recovery of exploratory capacity after ectopic pituitary homografts in Snell Dwarf mice (dw/dw).

The effects of ectopic pituitary homografts on free behavior were studied over a period of one month in adult Snell Dwarf mice. Because of anterohypophyseal deficiency, these animals exhibit dwarfism, sterility, and marked behavioral deficits. Beginning on the 16th day after surgery, in addition to a considerable weight gain, grafts result in the total disappearance of inactivity with passive social contact--the behavior most frequently observed in the mutants--to be replaced only by exploration--the most frequently observed behavior in controls. The treatment totally restores the latter behavior. Specific hormonal treatments and biochemical manipulations at different stages would enable identification of the hypophyseal hormones and/or the growth factors involved in the behavioral and morphological changes.

Animals↗
PubMed1984

Impairment of responses to novelty by apomorphine and its antagonism by neuroleptics in mice.

The effects of several doses of apomorphine (AP: 0.062-8 mg/kg) on novelty preference (NP) in male Swiss mice were studied. AP induced a dose-dependent reduction of NP as well as of locomotor activity. The decrease in NP appeared to be related to the effect of the drug in reducing locomotion, and may be explained by a drug-induced increase in perseverance and stereotypy interfering with locomotion and NP by response incompatibility. These results contrast with those obtained with methamphetamine (MA) in a previous study (Misslin and Ropartz 1981) replicated here which also shows a reduction of NP. Furthermore, the neuroleptic thioridazine did not antagonize the effects of AP or MA on NP in mice, whereas the substituted benzamides tiapride and sulpiride did so. The substituted benzamides appear to act selectively on a restricted dopamine receptor population.

Animals↗
PubMed1984

[Beneficial effects of pituitary grafts under the renal capsule on behavior of dwarf mutant mice].

The effects of pituitary grafts under the kidney capsule were studied in "dwarf" mutant mice which because of anterohypophyseal deficiency, exhibit dwarfism, sterility and important behavioral deficits. One month after grafting, the body weight was 120% in the grafted mutants while only 11 and 8% respectively in normal and sham-grafted controls. At the behavioral level, the animals were examined on 2 tasks: spontaneous alteration in a T maze and passive avoidance (step-through). Grafted mutant mice, as well as sham-grafted normal controls, were able to alternate successfully, while the sham-grafted "dwarf" mice persevered. In the step-through task, grafted animals as well as sham-grafted normal mice, avoided, entering the dark compartment, 24 h after the shock trial. On contrast, sham-grafted dwarf mice did not show passive avoidance of the shock. According to the literature, pituitary grafts under the kidney capsule secrete high levels of prolactin and very little, if any, of other pituitary hormones. It is not yet clear how the presence of only prolactin can explain the body weight and the maintenance of the behaviors we investigated.

Animals↗
PubMed1982

Effects of isolation, handling and novelty on the pituitary--adrenal response in the mouse.

Male Swiss strain mice were individually- or group-housed for four weeks. Basal corticosterone levels did not differ with the type of housing, providing no support for the suggestion that the condition of the individually-housed mouse is stressful. Plasma corticosterone levels also were determined for mice which had been either left undisturbed or exposed to new cages which differed from their home cages by varying degrees. There were elevations in mean plasma corticosterone levels corresponding to the degree of difference between the home cage and the new cage. This finding supports the suggestion that changes in 11-OHCS levels are sensitive measures of environmental changes. Mice forced to remain in novel places exhibited higher plasma corticoid concentrations than animals which were given the opportunity to move freely between familiar and novel places. Corticoid values, as well as neurophysiological and behavioral responses, suggested that the stress induced by forced exploration might be due to the fact that animals are prevented from freely regulating their exposure to novel places rather than to novelty per se.

Animals↗
PubMed1981

Effects of methamphetamine on novelty-seeking behaviour by mice.

The effects of several doses from 0.125-3 mg/kg of methamphetamine on the novelty-seeking behaviour of male Swiss albino mice were studied. Methamphetamine induced a dose-dependent inhibition of novelty preference. Furthermore, a dose of methamphetamine (1 mg/kg) which strongly decreased novelty preference in naive mice induced a significantly lower decrease in exploration of subjects previously exposed to novelty. These data provide some support for Berlyne's (1967) suggestion that amphetamine has a disruptive effect on exploration by producing over-arousal.

Animals↗
PubMed1979

Effects of rearing in different environments on subsequent environmental preference in rats.

Environmental preference of male rats reared during 2 months after weaning either in a complex and changing environment (EC) or in empty laboratory cages (SC) was assessed in 4 different experiments. For 2 weeks after differential rearing, rats were placed in groups of 6 in testing cages which were divided into 2 compartments with communicating holes. One of these compartments was empty; the other contained 6 objects (complex compartment). Daily, 3 objects were moved from 1 compartment to the other and replaced by new ones. The preference for any of the compartments was chiefly assessed by the localization of feces (Experiments I and II) and directly by the localization of the animals through videorecording (Experiments III and IV). Both EC and SC rats showed a significant preference for the empty compartment during both light and dark portions of the daily cycle, but particularly during the light portion.Moreover, EC and SC animals differed from one another in that the SC rats showed a stronger preferences for the empty compartment than the EC rats, especially when active. General preference for the empty compartment seemed to diminish slowly, but EC and SC rats tended to remain distinct in habitat selection, at least during the period tested. This behavioral difference, tentatively interpreted in terms of neophobia, might constitute a possible mechanism for automaintenance of differential rearing effects.

Animals↗
PubMed1976

[Effect of an irreversible inhibitor (RMI71645) of gamma-aminobutyric acid (GABA) transaminase on spontaneous and conditioned activities of mice].

The RMI, an irreversible inhibitor of GABA transaminase, inhibited, at the dose of 100 mg/kg, the activity of Mice placed in an open-field. At lower doses, RMI improved the activity in open-field and the number of conditioned avoidance reactions. Results are correlated with increase of the level of brain GABA, following administration of RMI.

4-Aminobutyrate Transaminase↗
PubMed1976

Action of di-n-propylacetate on the spontaneous and acquired behaviour in goldfish, mice and rats.

The action of n-dipropylacetate (nDPA) is related to the dose. In low doses, nDPA improved the number of conditioned responses with negative reinforcement. In higher doses, the drug inhibited spontaneous and conditioned behaviour. An nDPA produces an increase in gamma-aminobutyric acid (GABA) brain level, results are discussed in relation to the inhibitory action of GABA in the central nervous system.

Acetates↗
PubMed1976

Catecholamines and operant response rates in albino rats.

The action of d-amphetamine was studied in rats conditioned on an operant "multiple" schedule of reinforcement. The action of this drug depended on the control response rate of each individual. The turnover of brain norepinephrine (NE) and dopamine (DA) was estimated in the whole brain of the same rats; the steady state level of NE, but not the turnover time, was significantly correlated with the average response rate of each subject. No significant correlation was found between this response rate and the turnover of DA. It is proposed that the response rate dependent effects of d-amphetamine might be related to brain NE levels.

Animals↗
PubMed1975

The effects of n-dipropylacetate on the acquisition of conditioned behaviour with negative reinforcement in mice.

n-Dipropylacetate (nDPA), at a dose of 100 mg/kg, has a facilitating action on the acquisition of conditioned reactions with negative reinforcement in mice. On the other hand, nDPA reduces the number of conditioned reactions with a dose of 200 mg/kg. These effects of nDPA on conditioned behaviour are correlated with the increase of the level of brain gamma-aminobutyric acid, following administration of nDPA.

Animals↗
PubMed1975

Aversive effects and retention impairment induced by acetoxycycloheximide in an instrumental task.

AXM, when subcutaneously injected during the first 3 min following the acquisition of a nondiscriminative instrumental learning task, induced an aversion for the food reinforcement which had been associated with the training situation and with the pharmacological treatment. The high number of nonreinforced responses preceding the first reinforced response(RR) that animals performed when tested 6 days after AXM treatment, was not due to forgetting of the lever significance, but to this aversion. Animals treated with AXM showed low levels of lever pressing response and long latencies for their first RR; this deficit did not seem only to be due to food reinforcement aversion; it disappeared, as well as food aversion, when food reinforcement which had been associated with the learning situation and to treatment, was added to the daily feeding regimen during treatment-test interval. It has been shown, moreover, that more than 90 percent of cerebral protein synthesis was inhibited during the 5 hr following subcutaneous AXM injection. These findings are interpreted as an indication that AXM does not affect memory consolidation of a non discriminative instrumental learning.

Animals↗