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Biomedical subjects

U Scapagnini

Publications and source records attributed to U Scapagnini.

At least 109 records · Page 6Linked to original sources
PubMed1982

Effects of calcitonin on rat extrapyramidal motor system: behavioral and biochemical data.

The effects of i.v.c. injection of human and salmon calcitonin on biochemical and behavioral parameters related to the extrapyramidal motor system, were investigated in male rats. Calcitonin injection resulted in a potentiation of haloperidol-induced catalepsy and a partial prevention of apomorphine-induced hyperactivity. Moreover calcitonin induced a significant decrease in nigral GAD activity but no change in striatal DA and DOPAC concentration or GAD activity. The results are discussed in view of a primary action of calcitonin on the striatonigral GABAergic pathway mediating the DA-related behavioral messages of striatal origin.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1982

Behavioral responses of long-term hyperprolactinaemic rats.

Rats with long-term endogenous hyperprolactinaemia induced by pituitary homografts under the kidney capsule displayed an enhancement of amphetamine- and apomorphine-induced stereotypy, a facilitated acquisition of active avoidance behavior and a decreased responsiveness to electrical footshock. However, no difference between homografted and sham-operated rats was observed with respect to grooming behavior. It is concluded that at least two processes occur during prolonged hyperprolactinaemia, i.e. development of tolerance to prolactin with respect to enhanced grooming activity and of supersensitivity of postsynaptic dopaminergic receptor systems. These two processes may be dependent or independent from each other.

Adrenal Glands↗
PubMed1982

Comparative effects of estrogens and prolactin on nigral and striatal GAD activity.

The comparative effects of a 10 day estrogen treatment and estrogen independent hyperprolactinemia on nigral and striatal glutamic acid decarboxylase (GAD, EC 4.1.1.15) activity were investigated in male rats. Data obtained show that estrogen treatment decreases GAD activity in substantia nigra, while an increase was observed in conditions of hyperprolactinemia induced by adenohypophysis homograft or acute and chronic sulpiride injection. The possibility of an opposite modulation of strio-nigral GABAergic system by estrogens and prolactin is suggested.

Animals↗
PubMed1982

Sulpiride effects on nigral and striatal glutamic acid decarboxylase activity: a possible involvement of prolactin.

Sulpiride, a benzamide derivative neuroleptic, was shown to significantly increase glutamic acid decarboxylase activity in substantia nigra and corpus striatum in either acutely or chronically injected male rats. Hypophysectomy completely prevented this effect suggesting an involvement of an anterior pituitary factor in the central action of sulpiride. Prolactin might possibly mediate the effects of sulpiride since it is known to increase prolactin secretion by an action at the level of the anterior pituitary. Consistent with this hypothesis was the finding of a similar increase in nigral and striatal glutamic acid decarboxylase activity in hyperprolactinemic animals in which an anterior pituitary had been implanted under the kidney capsule.

Animals↗
PubMed1982

Aromatization of testosterone by adipose tissue and sexual behavior of castrated male rats.

The influence of aromatization of testosterone occurring in adipose tissue has been studied in castrated obese male rats. The treatment for 30 days with a subliminal dose (115 micrograms/kg per day) of testosterone propionate improved significantly the sexual performance of castrated obese male rats as compared to the nonobese controls. Untreated castrated obese animals did not show any enhancement of sexual behavior. Furthermore, obesity failed to improve sexual performance in intact male rats. Measurements of plasma levels of testosterone and 17 beta-estradiol showed an increase in aromatization of testosterone in obese rats. Present data suggest that adipose tissue can be considered an important site for aromatization of testosterone to 17 beta-estradiol, and that aromatization is involved in the activation of sexual behavior in castrated male rats.

Adipose Tissue↗
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↗
PubMed1981

Behavioral effects of phosphatidylserine in aged rats.

The behavioral effects of 5 days of administration of phosphatidylserine (PS) was studied in aged rats. The intraperitoneal (5, 10, and 20 mg/kg) or intracerebroventricular (5, 10, and 20 micrograms/2 microliters) injection of PS liposomes caused a facilitated acquisition of active avoidance behavior as studied in shuttle-box and pole jumping test situations. The retention of active and passive avoidance responses was also improved. No substantial difference between PS-treated and control animals was apparent either in the responsiveness to electrical footshock or in the motor activity tested in an open field. Grooming behavior appeared to be enhanced in rats treated with the highest dose of the substance. Since PS affects both central catecholaminergic and cholinergic transmission, which is known to be impaired in old animals, the possibility that the behavioral effects of PS involve brain dopamine and/or acetylcholine systems is discussed.

Aging↗
PubMed1981

Comparative effects of chronic haloperidol and sulpiride treatment on nigral and striatal GABA content.

Nigral and striatal GABA contents were assayed in male rats treated chronically with haloperidol or sulpiride, two dopamine-receptor blocking agents that have different neuropharmacological spectra in regard to their biochemical, behavioural, and clinical properties. No great difference was observed between the chronic effects of haloperidol and sulpiride on nigral and striatal GABA content. However, low doses (30 micrograms/kg, intraperitoneally) of the dopamine-receptor agonist apomorphine, injected 12 h after the discontinuation of chronic haloperidol or chronic sulpiride treatment, induced opposite changes in nigral GABA levels suggesting the existence of a different "status" of the dopamine receptors during the 12 h-period following the withdrawal of haloperidol or sulpiride.

Animals↗
PubMed1981

In vivo and in vitro interference of phosphatidylserine liposomes on prolactin secretion in the rat.

The effect of sonicated suspensions of phosphatidylserine (PS), an acidic phospholipid, was investigated on prolactin secretion utilizing in vivo and in vitro approaches. Acute and chronic administration of PS reduced plasma prolactin levels during different phases of circadian rhythms. The phospholipid was able to inhibit the plasma prolactin surge, which occurs in cycling female rats on the afternoon of proestrus. The time course of PS on prolactin secretion was characterized by a short latency (15 min) and a long duration of action (6 h). In rats with hypothalamic deafferentation PS partially reduced the increase of circulating prolactin induced by pretreatment with alpha-methyltyrosine. An inhibition of prolactin release was observed if anterior pituitary glands were incubated in presence of PS. This effect was prevented by the addition of the dopamine antagonist sulpiride to the medium. In conclusion, PS decreases prolactin secretion both in vivo and in vitro. The inhibition of the hormone secretion appears to be due to the action of PS at the level of the pituitary; however, a concomitant stimulatory action on the turnover of the tuberoinfundibular neurons cannot be ruled out.

Animals↗
PubMed1981

Influence of hyperprolactinemia induced by adenopituitary transplantation under the kidney capsule on the glutamic acid decarboxylase activity in various brain regions.

Glutamic acid decarboxylase activity was assayed in rat substantia nigra, corpus striatum, medial basal hypothalamus and cerebellum under conditions of hyperprolactinemia induced by transplantation of adenopituitary under the kidney capsule. The results indicate that hyperprolactinemia induces a slight increase in the glutamic acid decarboxylase activity of substantia nigra and medial basal hypothalamus and a more evident increase at striatal level. No change was observed in the cerebellum.

Animals↗
PubMed1981

Serotonin nerve endings and regulation of pupillary diameter.

On the basis of the effects caused by 5-6-dihydroxytryptamine (5-6-DHT) on the serotonin nerve endings (chronic degeneration with depletion of the mediator), the eventual existence of serotoninergic fiber regulating pupillary diameter (PD) and intraocular pressure (IOP) was studied from a functional point of view. For the miotic effect found after administration of 5-6-DHT in rabbit, not accompanied by any change in the IOP, the hypothesis of a coparticipation of the serotoninergic fibers in the regulation of the PD is proposed, thus sustaining the concept that both PD and IOP respond to mechanisms of autonomous control. A phenomenon of receptorial supersensitivity to serotonin after the lesion of the nerve endings, dependent on 5-6-DHT, was also encountered.

5,6-Dihydroxytryptamine↗
PubMed1980

Increase in the LHRH content of the organum vasculosum of the lamina terminalis and the medio-basal hypothalamus six hours after injection of kainic acid into the rat medial preoptic area.

The luteinizing hormone-releasing hormone (LHRH) content of the organum vasculosum of the lamina terminalis (OVLT) and that of the medio-basal hypothalamus (MBH) was studied 6 h after the injection of 1 microgram of kainic acid into the medial preoptic area (MPOA) at the day of diestrus. The injection resulted in a highly elevated LHRH content in the OVLT which exceeded that of the controls observed on the afternoon of proestrus. LHRH content in the MBH increased significantly, however, it did not reach the peak value of proestrus. No change occurred in luteinizing hormone (LH) and prolactin (PRL) levels, while serum follicle-stimulating hormone (FSH) values decreased significantly. The increased LHRH content of the OVLT and of the MBH might be due to an enhanced LHRH synthesis and/or to the stimulation of neurons which inhibit LHRH release.

Animals↗