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Biomedical subjects

J M van Ree

Publications and source records attributed to J M van Ree.

At least 127 records · Page 7Linked to original sources
PubMed1984

The twitch in horses: a variant of acupuncture.

The twitch procedure in horses attenuates the increase in the heart rate evoked by pain-inducing stimuli and the reaction of the animals to such stimuli. Endorphin systems are probably involved in the effectiveness of the twitch, since its action is blocked by naloxone and its application increases plasma concentrations of immunoreactive beta-endorphin. The mode of action of the twitch cannot be explained by the generally accepted theory of divertive pain and may resemble that of classical acupuncture.

Acupuncture Therapy↗
PubMed1984

gamma-Endorphin and N alpha-acetyl-gamma-endorphin interfere with distinct dopaminergic systems in the nucleus accumbens via opioid and non-opioid mechanisms.

Low doses (10 ng) of the dopamine agonist apomorphine induced hypolocomotion when injected into the nucleus accumbens of rats. This behavioral response was antagonized by local treatment with either the opioid peptide gamma-endorphin (gamma E) or the non-opioid peptide N alpha-acetyl-gamma-endorphin (Ac gamma E) in a dose of 100 pg. High doses of apomorphine (10 micrograms) r amphetamine (2 micrograms) injected into the nucleus accumbens resulted in hyperlocomotion. This response was blocked by pretreatment with gamma E but not with Ac gamma E. This effect of gamma E could be prevented by local treatment with naloxone. Neither peptides interfered with the apomorphine-induced stereotyped sniffing when the substances were injected into the nucleus caudatus. It is concluded that gamma E and Ac gamma E differentially interact with distinct dopaminergic systems in the nucleus accumbens of the rat brain via an opioid and a non-opioid mechanism, suggesting that the peptide fragments originating from pro-opiomelanocortin may be specifically implicated in the control of dopaminergic activity in this brain area.

Animals↗
PubMed1984

Analysis of the facilitatory effect of the ACTH-(4-9) analog ORG 2766 on active social contact in rats.

Pairs of male rats were tested for active social interaction, either in a familiar test arena under low illumination or in an unfamiliar test arena under high illumination conditions. Rats tested in an unfamiliar environment and under high light, spent less time in active social contact than rats tested under familiar, low light conditions. This effect was most pronounced during the first half of the 10 minute test period. Intraperitoneal injections of ACTH-(1-24) and ACTH-(4-10) (50 micrograms/kg) administered 5 minutes before the test decreased, whereas the same dose of the synthetic ACTH-(4-9) analog ORG 2766 increased the time spent in active social contact, when rats were tested under unfamiliar, high light conditions. The effects of ACTH-(4-10) and ORG 2766 were present in the second and first half of the test period respectively. Dose response relationship studies with ORG 2766 showed that 0.5 micrograms/kg of this peptide facilitated social contact under both test conditions and the dose response relation followed an inverted U-shaped curve under the familiar low light condition, but not under the unfamiliar, high light condition. ACTH-(4-10) and ORG 2766 failed to influence active social contact, when administered 30 minutes before the test. The change in social contact by ACTH-(4-10) and ORG 2766 was not accompanied by an alteration in ambulation of the rats. It is concluded that ACTH-(4-10) and ORG 2766 decrease and increase respectively social interaction of pairs of rats. The expression of these effects however, depends on the test and treatment conditions and may be related to the action of brain-born ACTH-like peptides.

Adrenocorticotropic Hormone↗
PubMed1984

delta 1-Tetrahydrocannabinol-induced circling behavior in rats: a possible measure of psychotomimetic activity?

Relatively high dosages of delta 1-tetrahydrocannabinol (delta 1-THC) markedly suppressed almost all normally occurring behavioral elements in rats as observed in both a small and a large open field. This effect persisted following repeated treatment and testing for 3 consecutive days. The psychotropically inert but related compound cannabidiol (CBD) did not suppress behavior, but in contrast had a mild activating effect. Both compounds decreased defecation during the test procedure. In addition, delta 1-THC, but not CBD, induced a bizarre circling and turning response, that was evident over all 3 test days and occurred even when the rats were deeply sedated. It is suggested that an analysis of this phenomenon may be useful in measuring the psychotomimetic action of delta 1-THC and similar compounds in rats.

Animals↗
PubMed1984

delta 1-Tetrahydrocannabinol but not cannabidiol reduces contact and aggressive behavior of rats tested in dyadic encounters.

A low and a high dose of delta 1-tetrahydrocannabinol (delta 1-THC) and of cannabidiol (CBD) were IP injected in rats that had been isolated for 7 days. Forty-five minutes after injection, the rats were tested for social interactions with non-isolated, untreated test partners in dyadic encounters under standardized conditions. Different aspects of social behavior were analyzed. The high dose of delta 1-THC (10 mg/kg) prevented nearly all social interactions. The low dose of delta 1-THC (1 mg/kg) exerted selective and specific effects on social interactions. Social contact behavior, including crawl over/mounting, and social grooming, and aggressive behavior, including fighting, kicking, and biting, were markedly decreased, whereas social exploratory behavior (exploration of the partner and anogenital investigation) and the behavioral item, approach/follow, were hardly affected by delta 1-THC treatment. Both doses of CBD (2 and 20 mg/kg) failed to change the various aspects of social interaction. It is postulated that the effects of delta 1-THC on close and intimate contact behavior of rats may contribute to the understanding of marihuana taking in humans.

Aggression↗
PubMed1984

Neuropeptides and social behavior of rats tested in dyadic encounters.

The effects of various neuropeptides on social behavior was studied in a test procedure in which 7-day isolated animals were tested together with non-isolated partners in dyadic encounters. The short-term isolation procedure increased the frequency and duration of social activities of the rats, but hardly affected non-social explorative behaviors of the animals. Systemic injection of certain neuropeptides, i.c. prolyl-leucyl-glycinamide (PLG), thyrotropin releasing hormone (TRH) and the ACTH 4-9 analog ORG 2766, reversed the isolation-induced increase in social activity, similarly as previously observed with antidepressant drugs. Subcutaneous treatment with beta-endorphin, alpha-endorphin and des-Tyr-gamma-endorphin increased social interactions in 7-day isolated animals. beta-Endorphin enhanced social behavior of non-isolated rats as well, whereas gamma-MSH decreased the social interactions of these animals. Both peptides affected especially social contact behavior. The potent action of beta-endorphin suggests that this peptide and opioid systems may play a physiological role in social behavior. It is proposed that a possible functional antagonism between ACTH-like peptides, especially gamma-MSH, and beta-endorphin may operate in social behavior. The action of the peptides may be rather specific for social behavior, since none of the neuropeptides affected non-social explorative behaviors of the rats during the social interaction test.

Adrenocorticotropic Hormone↗
PubMed1984

Clinical, biochemical, and hormonal aspects of treatment with Des-tyr1-gamma-endorphin in schizophrenia.

Des-tyr1-gamma-endorphin (DT gamma E) was administered intramuscularly in a dose of 1 mg/day for 10 days to 18 neuroleptic-free schizophrenic patients in a double-blind crossover design. Six patients showed either a slight or no antipsychotic response; seven patients showed a moderate antipsychotic response; and the remaining five patients showed a marked antipsychotic response. DT gamma E led to a decrease of plasma prolactin levels in patients treated with DT gamma E in the first period of experimental treatment as compared to those treated with placebo. Neither plasma levels of growth hormone and cortisol nor cerebrospinal fluid concentrations of homovanillic acid, 5-hydroxyindoleacetic acid, and 3-methoxy-4-hydroxyphenylglycol were affected by DT gamma E. Patients suffering from a hebephrenic or paranoid type of schizophrenia and those presenting relatively fewer negative symptoms were most susceptible to treatment with DT gamma E. These data confirm and extend previous findings that DT gamma E has antipsychotic properties in a number of schizophrenic patients.

Adolescent↗
PubMed1984

Repeated naloxone administration in schizophrenia.

A double-blind study of repeated subcutaneous administrations of 20 mg naloxone was performed in 10 schizophrenic patients as part of a World Health Organization collaborative project. No clinically obvious treatment effects were observed. None of the analyzed psychopathological symptoms, including hallucinations and unusual thought content, showed a distinct improvement during the 4 consecutive days of naloxone treatment. A slight but statistically significant decrease of symptomatology was found shortly after placebo injection on the first 2 days of treatment. This effect was not present following naloxone treatment. These findings are discussed in view of the hypothesis that increased endorphin activity contributes to the symptomatology of schizophrenic syndromes.

Adult↗
PubMed1984

Ceruletide resembles antipsychotics in rats and schizophrenic patients. Preliminary report.

Peptides related to the C-terminal part of cholecystokinin, including ceruletide, were found to be active in a number of behavioral test procedures in rats, predicting antipsychotic action. In a subsequent clinical trial ceruletide was administered intramuscularly in a dose of 40 micrograms twice for 2 consecutive weeks to 6 neuroleptic-treated schizophrenic patients following a single-blind design. In 3 patients, a pronounced long-lasting antipsychotic effect was observed, while in the other 3 the response was less marked. It is suggested that ceruletide may be a potential antipsychotic peptide.

Animals↗
PubMed1983

The influence of neuropeptides related to pro-opiomelanocortin on acquisition of heroin self-administration of rats.

The influence of different neuropeptides related to pro-opiomelanocortin were tested on acquisition of heroin self-administration in rats. The animals were allowed to self-administer heroin intravenously on a continuous reinforcement schedule during 6 h daily sessions on 5 consecutive days. Treatment was performed subcutaneously 1 h before each daily session. It was found that the opioid peptides alpha-, gamma- and beta-endorphin hardly influenced acquisition of heroin self-administration, while the non-opioid fragments of alpha- and gamma- endorphin modulated this behavioral response. In fact, beta-endorphin (beta E) 2-9 tended to facilitate the rate of acquisition, while the gamma-type endorphins, des-Tyr1-gamma-endorphin (beta E 2-17) and des-enkephalin-gamma-endorphin (beta E 6-17), decreased heroin intake. Concerning the ACTH/MSH related peptides, a decreasing effect of heroin intake was found following treatment with (D-Phe7)-ACTH 4-10, with a high dose of the ACTH 4-9 analog Org 2766 and with gamma 2-MSH, while ACTH 1-24, ACTH 4-10 and a low dose of Org 2766 did not significantly influence self-injecting behavior. It is concluded that pro-opiomelanocortin serves as a precursor molecule for peptide fragments, which modulate the acquisition of heroin self-administration in rats.

Adrenocorticotropic Hormone↗
PubMed1983

Normalizing effect of an adrenocorticotropic hormone (4-9) analog ORG 2766 on disturbed social behavior in rats.

Short-term isolation increased the frequency of social interactions in rats tested in pairs, while pairs of rats placed in an unfamiliar test cage and subjected to a high level of illumination spent less time in active social contact. These changes in social behavior elicited by environmental manipulations were counteracted by treatment with the adrenocorticotropic hormone (4-9) analog ORG 2766. The peptide's normalizing effect may be mediated by endogenous opioid systems.

Adrenocorticotropic Hormone↗
PubMed1983

Electrical stimulation of the ventral tegmental area and catecholamine metabolism in discrete regions of the rat brain.

Data are presented which show a different pattern of dopamine and noradrenaline utilization in terminal regions of the A9 and A10 dopaminergic systems and in terminal regions of the dorsal noradrenergic bundle after electrical stimulation of the ventral tegmental area and an adjacent area. At the sites of the electrodes an enhanced turnover of noradrenaline was found. These results are discussed relating the location of the electrode sites and the location of the dopaminergic cell bodies A9 and A10 and catecholaminergic fibers passing through the MFB innervating forebrain and limbic structures. It is concluded that activation of parts of the A10 dopaminergic system and the A6 noradrenergic system is correlated with intracranial self-stimulation.

Animals↗
PubMed1983

Low doses of beta-endorphin increase social contacts of rats tested in dyadic encounters.

Social isolation for 7 days increases the frequency of social interactions of rats, when they are tested with non-isolated partners in dyadic encounters. Subcutaneous administration of beta-endorphin enhances the social interactions of the isolated animals. Especially contact behavior, which includes crawl over, mounting and social grooming is stimulated by beta-endorphin, whereas social explorative behavior and approaching/following are less or not changed by peptide treatment. Already 10 ng/kg of the peptide increases the social interactions, especially social contacts of the rats. Treatment with naltrexone does not interfere with the social interactions of the isolated animals, but completely antagonizes the beta-endorphin-induced increase of social behavior, suggesting that this effect of beta-endorphin is mediated by opiate receptor systems. It is postulated that beta-endorphin modulates close and intimate social contacts probably by its reward-inducing properties.

Animals↗
PubMed1983

Uniquely, gamma-endorphin induces an effect that is both opiate- and neuroleptic-like.

Bilateral injection of gamma-endorphin into the nucleus accumbens of rats antagonizes the hyperlocomotion elicited by local treatment with relatively high doses of apomorphine. beta-Endorphin, alpha-endorphin, [Met]enkephalin, [Leu]enkephalin and des-Tyr1-gamma-endorphin do not mimic this effect of gamma-endorphin. Previous studies have shown that this antagonism by gamma-endorphin is mediated by a naloxone sensitive receptor system. It is concluded that uniquely, gamma-endorphin has an action that is both opiate- and neuroleptic-like.

Animals↗