Monoamines in the bird median eminence. Failure of cocaine to block the accumulation of exogenous amines

Behavioural effects induced in rats and chicks by D2 dopamine agonists

In a first series of experiments, different selective dopamine D2 receptor agonists (B-HT 920, B-HT 958, SND 919, CQ 32-084, CQP 201-403, and lisuride) and the D1/D2 agonist apomorphine were IP injected into adult male rats. At low doses, they elicited repeated episodes of penile erection and stretching-yawning: at all doses tested, B-HT 920, B-HT 958, and CQ 32-084 also induced hypomotility, a sign that, in the case of high doses of SND 919, CQP 201-403, lisuride, and apomorphine, was replaced by stereotyped behaviour. In a second series of experiments, the same D2 agonists and the mixed D1/D2 agonist apomorphine were IP injected at the same doses into chicks. The following behavioural signs were observed: hypomotility, sleep-like state, and stereotyped pecking. The results show that: 1. there are similarities between the behavioural effects induced by the DA agonists in rats and chicks; and 2. in both species some behavioural signs elicited by the DA ergic compounds are useful pointers to their specific neurochemical activity.

Effect of acute stress on catecholamine content in the hypothalamic nuclei of Japanese quail

Concentration of noradrenaline, adrenaline and dopamine in eight hypothalamic nuclei or areas (nucleus hypothalamicus medialis anterior, n. periventricularis magnocellularis, n. hypothalamicus lateralis anterior, n. hypothalamicus medialis posterior, n. hypothalamicus lateralis posterior, eminentia medialis, n. tuberis, area hypothalamica posterior) have been determined by a sensitive radioenzymatic micromethod in male Japanese quail restrained for 30 min. In control quail the highest concentrations were found in the a. hypothalamica posterior, n. periventricularis magnocellularis and n. hypothalamicus medialis anterior; the lowest was in the n. hypothalamicus medialis posterior. After restraint, noradrenaline concentrations decreased in the n. periventricularis magnocellularis and n. hypothalamicus medialis posterior. However, the concentration of adrenaline increased in the n. tuberis under the same conditions. In stressed animals the dopamine concentration was lower than in controls in the n. periventicularis and higher in the n. tuberis.

Catecholamine-containing neurons in the mesencephalic tegmentum of the chicken. Light, fluorescence and electron microscopic studies

The nucleus tegmentalis dorsalis (NTD) which may be homologous with the mammalian locus coeruleus was investigated in the chicken by means of light, fluorescence and electron microscopy. Results are summarized as follows: 1) Numerous neurons emitting green fluorescence by the Falck-Hillarp method were observed in the NTD of the chicken. By consecutive light and fluorescence microscopy on the same section it was established that these catecholamine(CA)-containing neurons clearly coincided with the cell group named nucleus tegmentalis dorsalis by Jungherr (1945). This procedure further showed that there were also non-fluorescent neurons in the NTD. 2) On the basis of electron microscopic observation, two types of neurons were recognized in the NTD: medium-(15-25 microns) and small-sized (10-15 microns) neurons. Medium-sized neurons had a round to oval nucleus with several deep infoldings and abundant organelles. From combined fluorescence and electron microscopic examination, they obviously corresponded with CA-containing neurons demonstrated by the Falck-Hillarp method. Small-sized neurons had a round nucleus surrounded by pale cytoplasm. They corresponded with non-CA-containing neurons. 3) From morphometric analysis, it was clear that CA-containing neurons contained a well-developed rough-surfaced endoplasmic reticulum and many lysosome-like dense bodies, unlike non-CA-containing neurons. This study was undertaken as the basis of a research program to elucidate the catecholaminergic projections from the NTD.

Brain noradrenaline concentration in seizure-prone chicks, Gallus domesticus

The mutant, sex-linked recessive px (paroxysm) gene, expressed in female White Leghorn chicks (Gallus domesticus), causes seizures beginning on approximately day 9 after hatching. In an attempt to determine possible central nervous system involvement in the seizures, brain levels of the putative transmitter noradrenaline were assayed. Brains of px chicks and controls (normal female siblings) were removed at 7, 14, and 21 days, weighed, and frozen immediately in liquid nitrogen for later analysis by the alumina-trihydroxyindoleamine method. Noradrenaline was assayed in whole brain and in 4 brain parts: optic lobes, brainstem, cerebral hemispheres, and cerebellum. No differences between px and controls were found in whole brain or optic lobe levels. Brainstem levels of noradrenaline increased significantly with time in both groups, though px increases were more rapid. Px chicks at 21 days of age had significantly higher levels or noradrenaline in the cerebral hemispheres, while cerebellar levels were significantly lower at the same age. The differences found in brainstem, cerebral, and cerebellar noradrenaline are of interest as possible explanations for the lowered body temperature, hyperexcitability, and lack of motor coordination seen in the px chicks.

Distribution of monoamine-containing terminals and fibers in the central nervous system of the chicken

In the mesencephalon of the chicken, the two large groups of CA terminals and fibers appeared to correspond to the dorsal and ventral bundles of the CA containing fibers in the rat. These ran rostrally in the medial forebrain bundle and appeared to terminate within the thalamus, hypothalamus, preoptic region and corpus striatum. 5-HT containing terminals and fibers also were observed in the mesencephalon and appeared to run rostrally in the medial part of the medial forebrain bundle. In comparison with the CA terminals, however, 5-HT terminals were for the greater part, difficult to observe in many areas of the brain. Based on the observation concerning postnatal ontogeny of monoamine-containing neurons, the chicken brain appears to acquire behavioral and functional maturity at an earlier stage after birth than does that of the rat. Effect of reserpine, nialnmide, L-Dopa and 5-HTP on the monoamine-containing terminals and fibers are briefly discussed.

Uptake and metabolism of catecholamines in the perfused hearts of different species

1. The uptake of (+/-)-(3)H-noradrenaline was studied in isolated perfused hearts of rat, mouse, guinea-pig, pigeon and toad (Bufo marinus), and the IC50 (concentration causing 50% inhibition) values for inhibition of uptake of (+/-)-(3)H-noradrenaline by (-)-noradrenaline were calculated. IC50 values ranging from 0.28 muM (rat heart) to 2.34 muM (toad heart) were found.2. In all species except the toad, (-)-noradrenaline showed a higher affinity than (-)-adrenaline for the uptake process, but the reverse was found for the toad heart.3. Mouse and pigeon hearts contained increasing amounts of metabolites of noradrenaline with increasing perfusion concentrations of noradrenaline, but the guinea-pig and toad hearts did not. The in vitro activities of noradrenaline catabolizing enzymes in heart homogenates were measured but did not explain the differences in the pattern of catabolism of noradrenaline found in the intact hearts of the different species.4. In all hearts except the toad, cocaine was an effective blocking agent for the uptake of (+/-)-(3)H-noradrenaline and led to an increase in (3)H-normetanephrine in these hearts. In the pigeon heart, cocaine plus phenoxybenzamine in the perfusate resulted in an inhibition of both (3)H-noradrenaline uptake and (3)H-normetanephrine formation.5. In guinea-pig and pigeon perfused hearts, the uptake of (3)H-noradrenaline into atria and ventricles reflected the relative concentrations of endogenous catecholamines in these regions, but this was not found for rat, mouse and toad hearts.6. It was concluded that species differences exist for both the accumulation and metabolism of catecholamines in isolated perfused hearts.