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Biomedical subjects

S Ahlenius

Publications and source records attributed to S Ahlenius.

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

Failure to antagonize the 8-hydroxy-2-di-n-propylamino)tetralin-induced facilitation of male rat sexual behavior by the administration of 5-HT receptor antagonists.

The administration of the putative 5-hydroxytryptamine (5-HT) agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and 5-hydroxytryptophan (5-HTP) produced a facilitation and an inhibition of male rat sexual behavior, respectively. The 5-HTP-induced inhibitory effects were at least partially antagonized by the administration of metergoline, methiothepine or pirenperone. However, none of these agents were able to counteract any facilitatory effects produced by 8-OH-DPAT. It is concluded that 8-OH-DPAT does not facilitate the expression of masculine sexual behavior in the rat by stimulation of 5-HT1 or 5-HT2 receptors.

5-Hydroxytryptophan↗
PubMed1984

Lisuride, LY-141865, and 8-OH-DPAT facilitate male rat sexual behavior via a non-dopaminergic mechanism.

In agreement with previous results from this laboratory, the ergot derivative lisuride (0.4 mg/kg IP) and the ergot congener 8-OH-DPAT (0.25 mg/kg IP) produced a marked facilitation of male rat sexual behavior. Furthermore, another ergot compound, the dopamine-2 selective agonist LY-141865 (2.5-20 mg/kg IP), was shown to facilitate male rat sexual behavior to the same degree. Neither the effects produced by LY-141865, nor the effects produced by lisuride or 8-OH-DPAT, were antagonized by pretreatment with the dopamine receptor blocking agent haloperidol, 0.16 mg/kg IP. A higher dose of haloperidol (0.32 mg IP), which produced clear extrapyramidal symptoms, was also ineffective in antagonizing the lisuride- or 8-OH-DPAT-induced facilitation of male rat sexual behavior. It is concluded that the stimulation of male rat sexual behavior produced by ergot and ergot-like drugs is mediated via a non-dopaminergic mechanism.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1984

Effects of (-)3-PPP on acquisition and retention of a conditioned avoidance response in the rat.

The administration of (-)3-(3-hydroxyphenyl)-N-n-propylpiperidine (3-PPP) was found to partially, but significantly, suppress the acquisition (4-8 mg/kg IP) and performance (8-16 mg/kg IP) of a conditioned avoidance response (CAR) in male Sprague-Dawley rats. All statistically significant effects were observed within 2 h of injection. Furthermore, using a situation in which the CAR was dependent on a visual successive discrimination, it was shown that discriminative performance was unaffected, and that (-)3-PPP (12.5-25 mg/kg IP) but not (+)3-PPP, suppressed the CAR. When (-)3-PPP (6.25 mg/kg IP) was combined with haloperidol (0.1-0.4 mg/kg IP), additive effects on the CAR performance were observed. Considering these effects, and the doses of (-)3-PPP required to suppress the CAR performance, it is concluded that the effects obtained in the present experiments are primarily due to a blockade of postsynaptic DA receptors.

Animals↗
PubMed1984

Behavioral and biochemical effects of subchronic treatment with (-)3-(3-hydroxyphenyl)-N-n-propylpiperidine in the rat: dopamine receptor sensitivity and tolerance.

Male Sprague-Dawley rats were treated for 3 weeks with (-)3-(3-hydroxyphenyl)-N-n-propylpiperidine (3-PPP). Twenty-four hours, but not 72 hours, after withdrawal of the treatment there was an increase in locomotor activity in comparison with saline treated controls. At the same time there was a decrease in striatal DOPAC and HVA and an increased locomotor activity response to apomorphine, indicating supersensitive dopamine receptors. There was no evidence for behavioral tolerance since the suppression of locomotor activity after an acute dose of (-)3-PPP was the same in (-)3-PPP-pretreated as in saline-treated controls. Plasma levels of (-)3-PPP in these animals were, however, slightly decreased.

Animals↗
PubMed1984

Apomorphine and haloperidol-induced effects on male rat sexual behavior: no evidence for actions due to stimulation of central dopamine autoreceptors.

The administration of apomorphine (0.2-0.8 mg/kg IP) or (+)3-PPP(4-8 mg/kg IP) produced a facilitation of the male rat sexual behavior. Apomorphine in lower doses, as well as the selective DA autoreceptor agonist (-)3-PPP were ineffective. Except for a decrease in number of intromissions and an increase in the postejaculatory interval at the highest dose (0.32 mg/kg IP) there were no effects after administration of haloperidol. These data indicate that activation or inhibition of the presynaptic dopamine receptor does not affect male rat sexual behavior.

Animals↗
PubMed1983

Suppression of exploratory locomotor activity in the rat by the local application of 3-PPP enantiomers into the nucleus accumbens.

It was found that (-)-3-PPP, 5-160 microgram/side produced a statistically significant suppression of exploratory locomotor activity after application to the nucleus accumbens. The (+)-isomer was about 8 times less potent in suppressing exploratory activity. Except for suppression of the locomotor activity by 160 micrograms of (-)-3-PPP no statistically significant effects were produced by either isomer applied in the neostriatum.

Animals↗
PubMed1983

Enhancement by the putative 5-HT receptor agonist 8-OH-2-(di-n-propylamino)tetralin of the acoustic startle response in the rat.

Two 2-(di-n-propylamino)tetralin (DPAT) compounds, 8-OH-DPAT and 5-OH-DPAT, with reported effects on central 5-HT and DA receptors respectively, were tested for their effects on the acoustic startle response in rats. 8-OH-DPAT was given in doses of 0.25-2.0 mg/kg IP and 5-OH-DPAT in doses of 1.0-8.0 mg/kg IP. Both compounds increased the startle response significantly in a dose-dependent manner, but 8-OH-DPAT appeared to be about 30 times as potent and to have a higher efficacy than 5-OH-DPAT. In addition, the effects on the startle response of L-5-HTP, 25-100 mg/kg IP, and L-dopa, 25-100 mg/kg IP, administration to animals pretreated with the inhibitor of aromatic L-amino acid decarboxylase, benserazide (25 mg/kg IP) were included for comparison. A small, but significant increase in the startle amplitude was found after the highest dose of L-5-HTP, whereas no effects were observed after L-dopa administration.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1983

Effects of neonatal treatment with 5,7-dihydroxytryptamine or 6-hydroxydopamine on the ontogenetic development of the audiogenic immobility reaction in the rat.

The ontogenetic development of the audiogenic immobility reaction (freezing) was studied in rats given intracisternal injections of the neurotoxins 5,7-dihydroxytryptamine (5,7-DHT), 25 micrograms, or 6-hydroxydopamine (6-OHDA), 100 micrograms, neonatally (Day 1). The duration of the freezing response was strongly reduced in the 5,7-DHT-treated rats between 20-30 days of age, when normal animals show very prolonged responses. During the same period increased motor activity was observed in the 6-OHDA-treated rats while only a slight reduction of the freezing response was noted. Biochemical analyses performed on brains from animals 35 days of age showed a selective reduction (about 50%) of whole brain levels of serotonin in the 5,7-DHT-treated rats, while the noradrenaline levels were selectively reduced by about 60% in the 6-OHDA rats. A longitudinal investigation on the effects of neonatal treatment with 5,7-DHT showed a persistent selective reduction of the whole brain level of serotonin up to at least 90 days of age. Since 5,7-DHT mainly affects the serotonergic pathways, the results suggest that the disturbances noted in the ontogeny of the freezing response may be due to interference with the developing serotonergic system.

5,7-Dihydroxytryptamine↗
PubMed1983

Suppression of exploratory locomotor activity by the local application of dopamine or l-noradrenaline to the nucleus accumbens of the rat.

Adult male Sprague-Dawley rats were administered dopamine (DA) or l-noradrenaline (l-NA) locally into the nucleus accumbens or in the neostriatum. Six minutes following the injections the animals were placed in an open field arena (700 X 700 mm) and their locomotor activity was recorded every 3 min for maximally 60 min. In the nucleus accumbens both DA (10-160 micrograms/side) and l-NA (2.5-40 micrograms/side) produced a suppression of the initial (0-3 min) exploratory locomotor activity in the open field arena. The highest doses of the respective drug, 80-160 micrograms of DA and 20-40 micrograms of l-NA, produced stimulation of the locomotor activity at a later time interval (6-9 min). The number of rearings during the initial exploration (0-3 min) was suppressed by DA (10-160 micrograms/side) as well as by l-NA (2.5-40 micrograms/side). When administered to the neostriatum, DA (80-160 micrograms/side) produced a stimulation of locomotor activity, 6-9 min after placement in the open field. The administration of l-NA (20-80 micrograms/side) to the neostriatum produced a suppression of the exploratory locomotor activity (0-6 min). The number of rearings were reduced by the administration of l-NA (20-80 micrograms/side) whereas no significant effect was observed after the administration of DA (5-160 micrograms/side). As assessed in the present experiments DA and l-NA produced identical effects in the nucleus accumbens, l-NA being about 4 times as potent as DA, whereas opposite effects were produced by l-NA and DA when applied to the neostriatum.

Animals↗
PubMed1982

Functional importance of nucleus accumbens noradrenaline in the rat.

l-Noradrenaline. HCI (l-NA), d-noradrenaline.HCI(d-NA) and dopamine.HCI (DA)were locally applied in the nucleus accumbens of awake rats. When the animals were observed in a dark open field arena it was found that low doses of l-NA or DA produced suppression of ambulatory activity followed by an increase in the activity at higher doses. l-NA was more potent than DA in producing these effects and about 4 times higher doses of DA were required to produce the same effect. d-NA was not without effects but was less efficient than DA.

Animals↗
PubMed1981

Effects of a new type of 5-HT receptor agonist on male rat sexual behavior.

8-Methoxy-2-(di-n-propylamino) tetralin (8-OMe-DPAT) and 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) are two new drugs exerting selective actions on brain 5-HT neurotransmission. In the present experiments we have investigated the effects of these two drugs on male rat sexual behavior. It was found that both drugs reduce the number of intromissions preceding ejaculation and shorten the ejaculation latency. These effects are extremely pronounced and several animals ejaculate at the first intromission. In addition 8-OH-DPAT produced a slight reduction of the post-ejaculatory interval. There were no significant effects on latency to initiate copulation or in the number of mounts preceding ejaculation. Finally, sexual behavior was partly or completely restored in castrated male rats after injection with 8-OMe-DPAT or 8-OH-DPAT.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗
PubMed1980

Stimulating effects of lisuride on masculine sexual behavior of rats.

Treatment of adult male rats with lisuride, an ergot derivative, resulted in selective changes in the masculine mating pattern. A dose-dependent decrease was found in the number of intromissions preceding ejaculation and in the ejaculatory latency. No other components of the mating pattern showed any significant alteration. Further, castrated sexually inexperienced rats treated with lisuride displayed a dose-dependent increase in complete heterosexual behavior.

Animals↗
PubMed1980

Enhanced suppression of a conditioned avoidance response by haloperidol but not phenoxybenzamine in rats with bilateral parafascicular lesions.

Male rats were subject to bilateral lesions in the parafascicular nucleus (PF) of the thalamus. The lesions had little or no effect on the performance of a pre-operatively acquired conditioned avoidance response. However, the PF lesioned animals displayed an enhanced response to the dopamine receptor blocking agents haloperidol or pimozide but not to the noradrenaline receptor blocking agent phenoxybenzamine. The results indicate that intralaminar thalamic nuclei and dopaminergic extrapyramidal motor pathways are functionally connected.

Animals↗
PubMed1980

Further evidence for an inhibitory role of central 5-HT in male rat sexual behavior.

The 5-hydroxytryptamine (5-HT) reuptake inhibitors zimelidine (10 mg/kg IP 1.5h pretest) or alaproclate (20 mg/kg IP 1.5h pretest) produced a prolongation of the ejaculation latency and of the post-ejaculatory interval in male rats treated with a subthreshold dose of 5-hydroxytryptophan (5-htp) (12.5 mg/kg IP 1h pretest). The 5-HTP-induced (50 mg/kg IP 1h pretest) prolongation of ejaculatory latency was effectively counteracted by administration of the 5-HT receptor blocking agent metergoline (1 mg/kg IP 1.5h pretest). All animals were treated with an inhibitor of peripheral aromatic amino acid decarboxylase, indicating that the effects are of central origin. The results support the contention that central 5-HT plays an inhibitory role in male rat sexual behavior.

5-Hydroxytryptophan↗
PubMed1980

Effects of acute lithium administration on conditioned avoidance behavior and monoamine synthesis in rats.

The effect of a single injection of various doses of lithium chloride was tested on conditioned avoidance behavior and on the accumulation of DOPA and 5-HTP after inhibition of aromatic amino acid decarboxylase. Lithium specifically suppressed conditioned avoidance behavior and reduced formation of DOPA, but not 5-HTP. The behavioral effect of lithium could be completely antagonized with additional L-DOPA treatment. The results indicate that lithium has a neuroleptlike effect on avoidance behavior, and it is suggested that some of the behavioral effects of lithium may be mediated via interference with central catecholaminergic mechanisms.

5-Hydroxytryptophan↗