PubMed Health⌕ Search

Biomedical subjects

R Hamburger-Bar

Publications and source records attributed to R Hamburger-Bar.

12 recordsLinked to original sources
PubMed1989

Peripheral versus central manifestations in the toxic interaction of lithium and pilocarpine.

Administration of a cholinomimetic agent 24 hr after a single injection of lithium chloride results in a profoundly toxic interaction. The lethality of the interaction was completely blocked by prior administration of scopolamine, but was not reduced by the peripherally acting cholinergic antagonist methscopolamine. Examination of the relative time courses of central neurotoxic and peripheral cholinergic manifestations showed that the peripheral manifestations were transient and were not enhanced by lithium pretreatment. The profoundly toxic consequences of lithium-cholinomimetic interaction may thus occur in the absence of enhanced cholinergic function in the periphery.

Animals↗
PubMed1987

Conditioned avoidance acquisition and extinction following repeated electroconvulsive shock: strain effect and response to vasopressin.

Male albino rats (Sabra strain) were exposed to electroconvulsive shock (ECS) once daily for periods ranging from 1 to 13 days, and proactive effects on conditioned avoidance response (CAR) acquisition and extinction were studied. CAR acquisition was intact following both single and repeated ECS, but extinction was accelerated by multiple ECS administration. These findings resembled the effect of repeated ECS on anterograde memory function in humans and confirmed previous observations based on a passive avoidance paradigm. However, extinction was not accelerated in a different rat strain (LC2). Parallel open field activity measures suggested that these findings were not related to ECS-induced alterations in locomotor activity. Administration of arginine vasopressin prior to each ECS, or following acquisition sessions, as well as 1-desamino-8-D-arginine vasopressin administration following acquisition sessions, did not ameliorate ECS-induced deficits in the Sabra rats. Differences between the present paradigm of ECS administration and those in which positive effects of vasopressin and other neuropeptides have been reported are discussed. The potential research applications of a rodent model of ECS-induced memory impairment that parallels deficits encountered in the clinical context are considered.

Animals↗
PubMed1986

Interstrain correlation between behavioural effects of lithium and effects on cortical cyclic AMP.

Six inbred mouse strains were studied to explore possible correlations between lithium effects on behaviour and on cortical cyclic AMP. The strains were fed lithium in ground food for 3 weeks before behavioural tests and ex vivo evaluation of cyclic AMP accumulation. Replicating previous reports, there was a significant inverse correlation (r = 0.73, n = 6) between spontaneous activity and noradrenaline-induced cyclic AMP, and an almost significant correlation (r = 0.67, n = 6) between spontaneous activity and adenosine-induced cyclic AMP accumulation. The effect of lithium to depress spontaneous activity correlated with its effect to inhibit adenosine-induced rises in cyclic AMP (r = 0.716, n = 6). There were significant strain differences in the behavioural responses to amphetamine. In two strains where amphetamine raised activity and lithium inhibited the amphetamine-induced rise, lithium also significantly inhibited the adenosine-induced rise in cyclic AMP. Two other strains showed amphetamine-induced rises in activity that were not inhibitable by lithium, and these strains showed no significant inhibition by lithium of adenosine-induced cyclic AMP accumulation. The remaining two strains showed no behavioural activity increase with amphetamine.

Amphetamine↗
PubMed1985

Vasopressin inhibition of cyclic AMP accumulation and effects on the learned response in inbred mouse strains.

The effects of a single injection of arginine vasopressin on the cyclic AMP responses of cerebral cortex slices to noradrenaline, forskolin and 2-chloro-adenosine were tested in six inbred mouse strains. The noradrenaline response was reduced in one strain and that to 2-Cl-adenosine in 2 strains. There was a positive correlation between the differences in the cyclic AMP response to 2-Cl-adenosine between control and AVP-treated mice and the differences in latencies during the extinction period of conditioned avoidance response learning.

2-Chloroadenosine↗
PubMed1985

Effects of vasopressin on noradrenaline-induced cyclic AMP accumulation in rat brain slices.

Addition of arginine vasopressin (AVP) or 1-desamino-8-D-arginine vasopressin (DDAVP) to rat cortical slices resulted in significant inhibition of the rise in cyclic AMP produced by incubation with 50 microM noradrenaline. A single injection of DDAVP (20 micrograms/rat) produced a reduced response to noradrenaline in derived cortex and caudate slices. In animals pretreated at day 5 of life with IP desipramine and intracisternal 6-hydroxydopamine (6-OHDA), both acute and chronic treatments with DDAVP resulted in a reduction in response in derived cortical, caudate and hippocampal slices. The 6-OHDA pretreated animals also showed reduced open-field behavioural activity after both acute and chronic DDAVP, while animals which were not pretreated responded to acute treatment only. The relationship between the effects of vasopressin on noradrenaline-induced cyclic AMP accumulation and its action on learning and memory is discussed.

Animals↗
PubMed1984

The effect of vasopressin treatment on learning in Down's syndrome.

Vasopressin is reported to enhance learning and memory in animal models. In 9 Down's syndrome patients DDAVP, a vasopressin derivative, was administered for 10 days, 40 micrograms per day, in a double-blind randomized crossover design. A visual-verbal paired associate learning test showed a not significant tendency for benefit with DDAVP. Word List memory was not improved with DDAVP treatment.

Adolescent↗
PubMed1984

Vasopressin effect on learning in 6-hydroxydopamine-pretreated rats: correlation with caudate vasopressin levels.

Conditioned avoidance learning was studied at 2 months of age in rats treated with intracisternal 6-OH dopamine (DA) at 5 days of life after desipramine pretreatment. Subcutaneous DDAVP 20 micrograms/rat or LVP 1 microgram/rat improved conditioned avoidance learning in the 6-OH DA-treated rats at least as much as in control rats. Caudate vasopressin levels significantly correlated with learning ability in the shuttle box in control rats (r = 0.69, n = 8), 6-OH DA-treated rats (r = 0.64, n = 8), 6-OH DA plus DDAVP-treated rats (r = 0.60, n = 9), or in the total sample (r = 0.59, n = 25, p less than 0.01).

Animals↗
PubMed1977

Peripheral and central androgenic stimulation of sexual behaviour of castrated male rats.

The effects of androgens on the maintenance and restoration of sexual behaviour (mounts, intromissions and ejaculations) of castrated male rats were studied. In the maintenance study the rats were treated during 5 weeks, starting one day following castration. Testosterone propionate maintained sexual behaviour at an almost normal level. The androgenoestrogen intermediate 19-hydroxytestosterone propionate was unable to prevent the decline in the number of ejaculations over the weeks although this hormone maintained the post-ejaculatory refractory period in those rats that ejaculated and also maintained normal sexual latencies. In the restoration study administration of testosterone propionate during 7 weeks to long-term castrated rats restored sexual behaviour to normal. 19-Hydroxytestosterone propionate treated rats displayed mounts but no other signs of sexual behaviour. The 5alpha-reduced androgen dihydrotestosterone propionate did not restore sexual behaviour. Testosterone propionate and dihydrotestosterone propionate stimulated peripheral target organs; 19-hydroxytestosterone propionate was ineffective in this respect. It has been suggested that testosterone might stimulate sexual behaviour in rats in two ways, i.e., via its aromatization to oestradiol in the brain, andy by stimulating growth of peripheral tissues via its 5alpha-reduction to dihydrotestosterone. In support for this view we have found that the combination of 19-hydroxytestosterone propionate and dihydrotestosterone propionate was effective in restoring the full pattern of sexual behaviour in castrated male rats.

Animals↗
PubMedDate not supplied

Apomorphine: facilitation of sexual behaviour in female rats.

Sexual receptivity of spayed female rats was studied by recording lordosis responses to a mounting male. Administration of apomorphine (0.25 mg/kg) to oestrogen+progesterone-primed females produced an increase in lordosis behaviour 2--48 hr after injection. An increase was also found when apomorphine was substituted for progesterone. These results suggest a role for dopamine in controlling sexual receptivity.

Adrenal Glands↗
PubMedDate not supplied

The effect of chronic vs. acute injection of vasopressin on animal learning and memory.

The effect of chronic and acute treatment with DDAVP, a vasopressin analog, was studied in 2 month old male rats, using an active avoidance test in a shuttle box. The experiment lasted 6 weeks: an acquisition period of 4 weeks and an extinction period of 2 weeks. Rats were treated one hour before behavioral testing 3 times a week for 6 weeks with either DDAVP 20 micrograms/rat/day for the whole period (chronic group) or with DDAVP for the first week and again once only on the first day of the extinction period (acute group) or with saline. Chronic treatment with DDAVP resulted in better acquisition and in a marked retardation of extinction compared with the acute treatment group. These results were obtained both in normal rats and in rats pretreated at age 5 days of life with intracisternal 6-OH dopamine.

Animals↗
PubMedDate not supplied

Animal and clinical studies of vasopressin effects on learning and memory.

Cognitive deficits of attention deficit disorder in childhood are poorly responsive to presently available medication. Vasopressin derivatives have been reported to enhance learning and memory in animals and in normal humans in controlled studies. This study reports on the effects of vasopressin on learning in rats and in children with learning disorders. Vasopressin treatment three times weekly for 6 weeks in rats appeared to be more effective in enhancing learning and retarding extinction than did vasopressin treatment given only at the beginning of learning and again at the start of extinction. These effects were also shown to be affected by pharmacogenetic factors, since in six inbred mouse strains some showed retarded extinction with vasopressin and others did not. In 17 children with attention and learning disorders, vasopressin derivative was given daily for 10 days and compared with 10 days of placebo treatment in a randomized, crossover, double-blind design. Story memory plus position learning were significantly improved by vasopressin derivative compared with placebo. The same trend of improvement was observed in nine Down's syndrome patients. In 15 other children with attention and learning disorders, a single dose of vasopressin derivative was compared with placebo in a randomized, crossover, double-blind design, and no benefit was found. These parallel animal and human studies suggest that repeated, but not single-dose, vasopressin treatment may benefit childhood learning disorders.

Animals↗