arquate

Our hypothesis was tested in respect to dopamine synthesis by non-dopaminergic neurons expressing individual complementary enzymes of the DA synthetic pathway. According to the hypothesis, L-dihydroxyphenylalanine (L-DOPA) synthesised in tyrosine hydroxylase(TH)-expressing neurons for conversion to dopamine. The mediobasal hypothalamus of rats on the 21st embryonic day was used as an experimental model. The fetal substantia nigra containing dopaminergic neurons served as control. Dopamine and L-DOPA were measured by high performance liquid chromatography in cell extracts and incubation medium in presence or absence of L-tyrosine...

Studies of the phylogenetic relationships of the Charadriiformes have been largely based on conservative morphological characters. During the past 10 years, many studies on the evolutionary biology of birds adopted phylogenetic information obtained from mitochondrial DNA, but few work on the Charadriiformes has been reported to date. Therefore, phylogenetic relationships and classification of the Charadriiformes remains controversial. In this study, we try to shed light on these relationships via DNA sequence analysis of the mitochondrial Cyt b gene in 12 species of Charadriiformes...

In vivo studies, serotonine synthesis in the rat fetal brain was inhibited by p-chlorphenylalanine from the 11th to the 20th embryonic day. Serotonine depletion significantly decreased thyrosine hydroxylase content in the neurones of males and females on the 21st embryonic day and in males--on the 35th postnatal day. In vitro, a co-culture of arquate nucleus' and raphe nucleus' embryonic neurones resulted in a sex-specific increase of the thyrosine hydroxylase level in the former neurones. The raphe nucleus' neurones manifested an increased level of serotonine...

Increase of the c-fos mRNA positive cells number was insignificant in 30 min. following activation of the rat hypothalamic structures with the tetanus toxoid (TT). Elevation of the c-fos mRNA positive cells number occurred in the hypothalamic' posterior (PHA), lateral (LHA), anterior (AHA), areas dorsomedial (DMH), and ventromedial (VMH) nuclei within 2 hours of the TT administration. In 6 hours the c-fos mRNA positive cells number decreased in PHA, LHA, DMH. The c-fos mRNA expression was stable in arquate and supraoptic hypothalamic nuclei following either the TT or saline administration...

Neonatal androgenization with 15--25 micrograms of testosterone-propyonate makes 43--54% of female rats sterile at puberty. Long-term administration of progesterone, clomiphen, luliberine, prostaglandin E2 induces ovulation but does not improve the fertility. Prostaglandin E2 decreases the amount of luliberine in the median emicnence and arquate nuclei within 30 min and increases the amount of luteinizing hormone in the blood of the control rats, whereas in the androgenized rats prostaglandin E2 is ineffective...

Complete surgical deafferentation of the medio-basal hypothalamus (MBH) in rats entails suppression of the oestrus cycle as well as a decrease of luteinizing hormone, estrogens and progesterone release into the blood due to a sharp fall of the luliberine content in the median eminence and arquate nuclei. No connection was revealed between the character of oestrus disturbances and the extent of damage or isolation of the arquate, ventromedial, supraoptic and paraventricular nuclei and the amount of Homori-positive neurosecreted in the MBH...

Ciproheptadin was found to depress the activating effect of serotonin in the preoptic brain area and in the hypothalamic arquate nuclei. Blockade of the type II serotonin receptors increased the content of luteinizing hormone in the blood in dioestrus-2 stage and in the morning during pro-estrus. Microiontophoretic administration of serotonin into the thalamic arquate nuclei during the blockade decreased the luteinizing hormone level in the blood in dioestrus-2 stage and in the morning during pro-estrus. Administration of serotonin into the preoptic area under the same conditions invariably decreased the hormone level in the blood...

Luliberin (LH-RH) was assayed radioimmmunologically in the hypothalamic fragments taken from male and female rats, intact or with isolated mediobasal hypothalamus. An increased amount of LH-RH was found in the fragments containing organum vasculosum of the lamina terminals (OVLT) and taken from intact males. LH-RH amount was negligible in isolated parts of hypothalamic fragments containing arquate nucleus of median eminence. OVLT of females was mu;ch richer with LH-RH than that of the males. The females though were characterized by a lower blood lutropin...

Hypothalamic suprachiasmatic nucleus (Schn) and Arquate nucleus (AN) were studied in female rats kept under constant illumination (rats with persistent estrus) or under light-dark cyclic illumination (normal estrus cycle). To destroy monoaminergic terminals, some rats from each group were injected with neurotoxic agents into the lateral cerebral ventricle. 6-hydroxydophamine which disturbs catecholaminergic terminals induced activation of the Schn and AN in rats with persistent estrus only. Destruction of serotoninergic terminals with 5,6-hydroxytryptophan induced activation of the Schn in rats with normal sex cycle and in those with a persistent estrus; the AN was also activated but only in rats with normal estrous cycle...