PubMed Health⌕ Search

Biomedical subjects

S R Chiocchio

Publications and source records attributed to S R Chiocchio.

At least 37 records · Page 2Linked to original sources
PubMed1984

Sympathetic innervation of the median eminence.

Bilateral removal of the superior cervical ganglia (SCG) decreases the adrenaline (NE) content of the median eminence. Bilateral removal of the SCG and bilateral deafferentation of the medial basal hypothalamus (MBH) together induce a greater decrease of NE content of the median eminence than that resulting from either one of the operations performed alone. Our results indicate that the median eminence receives a noradrenergic innervation arising from the SCG and that the SCG is the main origin of the NE remaining in the median eminence after bilateral deafferentation of the MBH.

Afferent Pathways↗
PubMed1984

Loss of peripheral chemoreflexes to hypoxia after carotid body removal in the rat.

Young Sprague-Dawley female rats (16-18 days old) were subjected to bilateral carotid glomectomy or the sham operation under halothane anaesthesia. After recovery, the rats were placed with non-operated peers. One to six months later glomectomised, sham-operated and control animals were anaesthetized with sodium pentobarbital. Respiratory minute volume and arterial pressure were recorded. Respiratory responses to few-breath administration of oxygen or nitrogen, and arterial pressure responses to carotid occlusion or tugging were tested. Oxygen produced transient hypoventilation and nitrogen transient hyperventilation in control, sham and 3 of 31 glomectomised rats. Bilateral vagotomy did not abolish these responses. In only those 3 glomectomised rats was carotid glomus tissue histologically identifiable. Carotid occlusion raised and tugging lowered arterial pressure in all animals. Glomectomy did not affect serum levels of GH, FSH, LH or PRL hormones but produced right ventricular hypertrophy. We conclude that peripheral chemoreception requires the presence of glomus tissue.

Animals↗
PubMed1984

Median eminence serotonin involved in the proestrus gonadotropin release.

Numerous studies have suggested that serotonin (5-HT) is involved in the regulation of anterior pituitary hormone release. In the present study, the 5-HT concentrations of the median eminence and anterior pituitary lobe were measured during the estrous cycle and lactation in order to correlate changes in 5-HT levels with changes in serum luteinizing hormone, follicle-stimulating hormone, and prolactin. On the day of proestrus, median eminence 5-HT concentrations declined significantly between 14.00 and 16.30 h at the beginning of the gonadotropin and prolactin surges. No changes in 5-HT concentrations were found between the morning and afternoon on other days of the cycle. In the anterior pituitary, the levels of 5-HT did not change during the estrous cycle. 5-HT turnover rates were also estimated in the median eminence on proestrus and diestrus 1. The median eminence 5-HT synthesis rate increased in the afternoon of proestrus at 16.30 h. 5-HT was also measured in the anterior pituitary and the median eminence of lactating rats in four experimental situations: mothers with their litter until decapitation, mothers separated from their pups 4 h earlier, and mothers separated from their pups 4 h earlier, after which the pups were allowed to suckle for 5 or 30 min. In spite of the acute changes in circulating prolactin, 5-HT levels in the median eminence were not affected in any situation studied. These results suggest that 5-HT in the median eminence is involved in the control of gonadotropin release. The data further suggest that 5-HT does not act directly on the anterior pituitary to modulate gonadotropin or prolactin release.

Animals↗
PubMed1980

Changes in adenohypophysial dopamine related to prolactin release.

In order to study whether changes in adenohypophysial dopamine are only related to PRL release or also to the variation of LH or FSH, dopamine (DA) in the pars distalis was measured during the estrous cycle and after castration of both male and female rats. Catecholamines were assayed using a highly sensitive radioenzymatic method. Dopamine and norepinephrine were also measured in the median eminence of the same rats. Adenohypophysial dopamine fluctuates during the estrous cycle, reaching its lowest levels on the afternoon of proestrus. Ovariectomy increases the DA content of the anterior lobe and estrogens reverse this effect. Orchidectomy does not change the amount of DA in the anterior pituitary. DA concentration in the median eminence parallels the changes observed in the pars distalis. We conclude that anterior pituitary dopamine concentration is closely related to PRL release and is not associated with changes in the release of LH or FSH.

Animals↗
PubMed1979

Involvement of adenohypophysial dopamine in the regulation of prolactin release during suckling.

Dopamine (DA) was measured in the anterior lobe of the pituitary and median eminence from lactating rats. The effect of pup separation and suckling was studied in order to correlate changes in DA levels with changes in serum PRL. In lactating rats separated from their pups, low levels of circulating PRL were found at 2,4, and 8 h. DA levels in the median eminence showed a decline at 2h; at 4 and 8 h of separation, a significant increase was observed. In the pars distalis, the concentration of DA increased with the length of the nonsuckling interval. Suckling induced a rapid rise in serum PRL levels in rats that were separated from their pups 4 h earlier. Under these conditions, a significant decrease in DA levels in the median eminence and pars distalis was observed as early as 5 min after the onset of suckling; at 30 min, the DA levels were still low. In the situations studied (suckling and pup separation), a negative correlation between serum PRL and DA levels in both the median eminence and pars distalis was always found.

Animals↗
PubMed1976

Acute changes in norepinephrine content in the median eminence induced by orchidectomy or testosterone replacement.

Median eminence catecholamines were measured in individual samples from intact, castrated, or sham-operated male rats, in order to correlate changes in catecholamine content with the early post-castration rise in serum LH levels. Both norepinephrine (NE) and dopamine (DA) were measured by an enzymatic-isotopic assay and advantage was also taken of a method recently developed that makes it possible to obtain the median eminence free of the surrounding hypothalamus. Determinations were made at 4, 8, or 24 h after surgery. All animals were killed between 1400 and 1600 h. It was observed that castration increases the ME content of NE significantly at all the times studied, with peak values 8 h after orchidectomy. Sham operation induced a significant decrease in NE content in the ME 4 h after surgery. By 8 h the NE values had returned to intact control levels. Both castration and sham operation induced a significant decrease in DA levels 4 h after surgery. By 8 h, DA values had returned to intact control levels in both groups. When the NE levels in castrated rats had reached the highest value, serum LH values had not departed from control levels, indicating that the change in NE content in the ME takes place prior to the expected rise in LH. Testosterone replacement therapy (40 mug/100 gBW) of castrated rats blocked the increase in NE content observed 8 h after castration. Dopamine levels were not affected by this treatment. These results support the concept that the NE contained in median eminence catecholaminergic terminals participates in the feed-back regulation of LH secretion in the male rat, while DA is apparently not involved under the present conditions.

Animals↗
PubMed1971

The carotid body as a neuroendocrine organ involved in control of erythropoiesis.

The carotid body is generally regarded solely as a chemoreceptor. This paper presents evidence that the carotid body is also an endocrine gland, secreting one or more erythropoiesis-controlling hormones. Its removal is followed by anemia and by a lack of reticulocyte response to daily bleeding. The removal of both carotid bodies results in a reduction of the high reticulocyte count induced by daily bleeding (5-40% of erythrocytes) down to 0.1% of erythrocytes. The injection of an extract of the carotid body causes reticulocytosis within 5 hr. This reticulocytosis attains its peak 48-72 hr after injection. Daily bleeding for 15 days produces an increase in weight of the carotid body and ultrastructural alterations that indicate increased protein synthesis in the main cells. The injection of plasma from efferent blood from the carotid body into either normal cats or cats from which both carotid bodies have been removed is followed within 6 hr by the appearance of large numbers of reticulocytes and macroreticulocytes in peripheral blood. Carotid body extracts and efferent blood plasma exhibited erythropoietin activity, which was demonstrated in the polycythemic rat by the (59)Fe incorporation method.

Animals↗