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Biomedical subjects

B Bohus

Publications and source records attributed to B Bohus.

At least 145 records · Page 8Linked to original sources
PubMed1982

Endogenous hyperprolactinaemia and avoidance behaviors of the rat.

The influence of endogenous hyperprolactinaemia induced by pituitary homografts under the kidney capsule on conditioned avoidance behaviors of the rat has been investigated. Acquisition of active avoidance behavior, as studied in shuttle-box and pole jumping test situations, appeared to be facilitated in homografted rats in comparison with sham-operated animals. Extinction behavior was not affected in the same tests. Retention of one-trial learning passive avoidance behavior in homografted rats was similar to that of sham-operated animals. Hyperprolactinaemia resulted in a diminished behavioral responsiveness to electrical footshock. It is concluded that endogenous hyperprolactinaemia selectively affects acquisition, but not retention performance of avoidance behaviors.

Animals↗
PubMed1982

Microinjection of arginine8-vasopressin antiserum into the dorsal hippocampus attenuates passive avoidance behavior in rats.

Antiserum to arginine8-vasopressin was microinjected bilaterally into the dentate gyrus of the dorsal hippocampus and the effect of passive avoidance behavior was studied. After the single learning trial of a passive avoidance response, immediate bilateral injection of 1 microliter antiserum (diluted to 1/50) attenuated passive avoidance responding 24 hr later. In immunocytochemical control studies with injection of undiluted antiserum into the dentate gyrus a spreading was observed towards the ventral hippocampus and the dorsal septum. Additionally, administration into the lateral ventricle of 2 microliters of 1/50 dilution of the antiserum did not affect the behavior. For an attenuation of passive avoidance behavior via intraventricular injection, 2 microliters of a 1/10 dilution of anti-AVP was required. These data suggest that endogenous vasopressin in the septo-hippocampal system might be involved in memory processes.

Animals↗
PubMed1982

Attenuation by arginine- and desglycinamide-lysine-vasopressin of a centrally evoked pressor response.

Arginine8-vasopressin (AVP) administered in a lateral cerebral ventricle attenuated the pressor response evoked by electrical stimulation of the mesencephalic reticular formation (MRF) in urethane-anesthetized rats. The blockade appeared to be dose-dependent in the range of 3-25 ng. The maximal effect was a 40% reduction of the pressor response. Desglycinamide9-lysine8-vasopressin (DG-LVP) exerted a similar effect on the pressor response. Both AVP and DG-LVP failed to affect basal blood pressure upon intraventricular administration. It is suggested that centrally acting neuropeptides related to vasopressin affect brain mechanisms involved in the regulation of blood pressure.

Animals↗
PubMed1981

Endogenous hyperprolactinaemia enhances amphetamine- and apomorphine-induced stereotypy.

Rats with endogenous hyperprolactinaemia induced by pituitary homografts under the kidney capsule were more sensitive to amphetamine and apomorphine with respect to drug-induced stereotypy, while a normal response was noted in drug-induced changes of locomotor activity, rearing and grooming. It is suggested that postsynaptic dopaminergic receptors, probably in the nigro-striatal system, may become selectively supersensitive in the endogenous hyperprolactinaemic animals.

Amphetamine↗
PubMed1981

Retention of passive avoidance behavior in rats following alpha- and gamma-endorphin administration: effects of post-learning treatments.

Neuropeptides related to beta-endorphin (beta-LPH61-91) profoundly affect avoidance behavior. That gamma- and alpha-endorphin (beta-LPH61-77 and beta-LPH61-76, respectively) influence memory processes, has been investigated on rats. Using a one-trial learning, step-through passive avoidance paradigm, it was found that gamma-endorphin attenuates later retention of passive avoidance behavior when administered immediately or 3 h after learning; alpha-endorphin facilitates this response when given immediately after learning. Neither gamma- nor alpha-endorphin influence retention when the treatment is postponed for 6 h after learning. These data are interpreted as suggesting an opposite effect of gamma- and alpha-endorphin on consolidation processes.

Animals↗
PubMed1981

Corticosterone binding capacity increases in contralateral hippocampus after partial unilateral hippocampectomy.

After unilateral dorsal hippocampectomy the binding of [3H]corticosterone to cytosol receptors in contralateral hippocampus was measured. For estimation of binding capacity the adrenals were removed bilaterally 24 h prior to sacrifice. The apparent maximal binding capacity (Bmax) for corticosterone in the contralateral hippocampus lobe was increased by 74 and 41%, respectively, 10 and 20 days after surgery. The data reveal a novel aspect of steroid receptor capacity control. It is suggested that compensation of altered amounts of receptor sites is an intrinsic property of the hippocampal corticosterone receptor system.

Adrenalectomy↗
PubMed1981

Gamma-melanotropin and brain function.

In view of the close structural similarity between the pro-opiocortin fragment, gamma-MSH, and ACTH/MSH-type peptides, the behavioural profile of gamma-MSH was explored. Attention was first focused on behavioural procedures in which ACTH/MSH-related neuropeptides have been found effective. It was found that gamma-MSH and ACTH-like neuropeptides had opposite effects on avoidance behaviour. In this respect the activity of gamma-MSH resembles that of opiate antagonists rather than that of beta-endorphin. Accordingly, ACTH(1-24) induced excessive grooming which is blocked by opiate antagonists and is attenuated by gamma-MSH. In addition, gamma-MSH injected into the periaqueductal grey matter of the brainstem of opiate-naive rats elicited symptoms reminiscent of those seen after opiate withdrawal. Gamma-MSH attenuated several effects of intracerebroventricularly administered beta-endorphin (e.g. antinociception, hypothermia, alpha-MSH release) and decreased the acquisition of heroin self-administration. Although gamma-MSH at rather high doses displaced naloxone from its specific binding sites in brain homogenates, it did not interfere with beta-endorphin-induced effects on in vitro muscle preparations (guinea-pig ileum; rat rectum). Interestingly, gamma-MSH induced relaxation of the rat rectum in vitro. It is postulated that gamma-MSH may attenuate beta-endorphin-induced effects by acting via gamma-MSH receptor sites (functional antagonism), although a pharmacological antagonism cannot be excluded as yet.

Adrenocorticotropic Hormone↗
PubMed1981

Prolactin induces grooming in the rat: possible involvement of nigrostriatal dopaminergic system.

The possibility that Prolactin-induced grooming involves the nigrostriatal dopaminergic system was studied. Intracerebroventricular injection of rat Prolactin (PRL) in an amount of 10 micrograms induced grooming in male rats, and neostriatal injection of haloperidol (1 microgram/1 microliter) markedly suppressed this effect. Local administration of 6-OHDA in the substantia nigra also abolished the influence of intracerebroventricularly administered PRL. Bilateral injections of PRL (10 micrograms/l microliters) in the neostriatum failed to induce grooming, whereas bilateral injections of peptide into the substantia nigra (1 microgram/0.5 micrograms) elicited the behavioral response. It is probable that PRL induces grooming in the rat by interacting with the nigrostriatal dopaminergic transmission through an action on the cell bodies rather than in presynaptic terminals or at the postsynaptic level of this system.

Animals↗
PubMed1980

Sexual dimorphism in passive avoidance behavior of rats: relation to body weight, age, shock intensity and retention interval.

Female rats were inferior to age- and weight-matched males in the retention of a step-through type passive avoidance response 24 and 48 hr after the learning. This sex difference could be observed at different intensities of foot shock which was used as aversive stimulus during the single learning trial. Additionally, unlike in males, retention of the passive avoidance response in the females was not the function of shock intensity. Male and female rats, however, showed similar passive avoidance if tested immediately after the learning trial. The results suggest the existence of sexual dimorphism in memory processes.

Age Factors↗