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Biomedical subjects

C Bouillé

Publications and source records attributed to C Bouillé.

At least 19 recordsLinked to original sources
PubMed1991

Gap junctional intercellular communication between cultured ependymal cells, revealed by lucifer yellow CH transfer and freeze-fracture.

In order to analyze intercellular communication between ependymal cells in mammalian brain, we have studied gap junctional communication of ependymal and glial cells in long term primary cultures derived from fetal mouse or rat hypothalamus and choroid plexus obtained in serum supplemented media with two complementary methods: 1) dye transfer of Lucifer Yellow CH after intracellular microinjection of the different cellular types, and 2) freeze-fracture of the same cultured ependymal cells. In our culture conditions, we have shown that the GJIC capacity to transfer dye was very different according to cellular types microinjected with Lucifer Yellow CH in the following respects: 1) in ependymal cells, GJIC was always important: ciliated ependymal cells, which are numerous in hypothalamic ependymal cultures (10-120 coupled cells), choroidal ependymocytes in plexus cultures (15-250 coupled cells), and non-choroidal ependymocytes in diencephalic roof cultures (10-30 coupled cells), and 2) in astroglial cells found in these primary cultures, no GJIC was observed in spite of the presence of well-differentiated gap junctions revealed by freeze-fracture replicas. All these results show a strong GJIC in ependymal cells and indicate the very good functional state of these cells in vitro.

Animals↗
PubMed1985

[Immunofluorescence localization of corticoliberin neurons in the brain of pigeons].

With immunofluorescence techniques using one anti-rat or two different anti-ovine CRF, the localization of corticotropin-releasing factor (CRF) producing neurons was characterized in frozen sections of pigeon brain. Colchicine was administered intraventricularly at various day hours. The CRF neurons were localized in the telencephalon: lobus parolfactorius, nucleus (n.) accumbens, anterior commissure; in the diencephalon: n. dorso-medialis and lateralis thalami and in different structures of the hypothalamus: n. praeopticus periventricularis and medialis, paraventricularis, supraopticus medialis, lateralis, ectomamillaris and in the stratum cellulare externum. Concerning the hypothalamic localizations, results are discussed in the light of physiological studies on corticotropic regulations in pigeons. Additional populations of CRF neurons were also located in various brainstem areas substantia grisea centralis, locus caeruleus, n. tegmenti dorsalis, sensorius principalis nervi trigemini, vestibularis latetalis, solitarius, nervi hypoglossi, in the dorsal area of the n. pontis lateralis and in the n. paramedianus paragiganto--cellularis, raphes, nervi facialis, subcaeruleus and the area ventralis. These particular localizations may lead to the assumption that CRF might be involved in nervous regulations other than those related to the corticotropic function.

Animals↗
PubMed1982

[Repercussions of anterior hypothalamic lesions on nycthemeral variations of plasma thyroxine and corticosterone in the pigeon].

Plasma thyroxine and corticosterone levels were determined by competitive protein binding assay, at 3 hr intervals, throughout the photoperiod. Pigeons were kept in controlled environment (21 +/- 1 degree C; 14L6-20: 10D). Intact controls exhibited low thyroxine (T4) and corticosterone (B) levels for the light phase of the photoperiod. Values were rising during the night, up to a peak at 03 hr. Electrolytic lesions were placed bilaterally in either the nucleus anterior medialis hypothalami or the n. preopticus, or the n. supraopticus. Circadian rhythms of both T4 and B were markedly altered in all lesioned pigeons, with a shift of very high T4 values to the morning times and a complete disorganization of B patterns, with very heterogeneous values. The possibility is raised that anterior hypothalamic formations participate in the endogenous oscillator circuitry in birds.

Animals↗
PubMed1981

Hypothalamic multiunit activity correlates of the adrenocortical response to stress.

The corticotropic response to stress was studied by means of multiple unit activity (MUA) recording from the adrenocorticotropic region of the hypothalamus, and plasma corticosterone (B) determination. MUA was permanently obtained and B was measured at 2, then 5 and 10 min intervals before and after neurogenic (electrical shocks) or systemic (ether inhalation) stress was applied. Experiments were made on steady unanesthetized, unrestrained thalamic pigeons. Post-stress alterations of MUA and B were closely in parallel, exhibiting a rapid and sustained increase in firing rate and shifting by 5-10 min, in corticosteronemia. Three successive and progressively decreasing peaks of MUA and B could be observed. Basal resting values were restored by approximately 90 min. Adrenocorticotropic responses to stress appear to be modulated through neural thalamic and/or rhombencephalic mechanisms.

Adrenocorticotropic Hormone↗
PubMed1981

Influence of dorsal hippocampus stimulation on the excitability of medial hypothalamic neurons in the rat.

Extracellular recordings from medial hypothalamic neurons in pentobarbital-anesthetized male Sprague-Dawley rats were evaluated during electrical stimulation in the ipsilateral and contralateral dorsal hippocampus/fimbria region. Similar short latency orthodromic (excitatory or inhibitory) responses were noted from both ipsilateral and contralateral stimulation sites indicating a bilateral projection. 14.5% of neurons responded to both stimuli, usually with a similar pattern of response. When neurons were also tested with ipsilateral basal or corticomedial amygdala stimulation, 21.5-22.8% of cells displayed orthodromic responses to both the hippocampus and the amygdala stimulus. 12.5% of medial hypothalamic tuberoinfundibular neurons also responded orthodromically to the hippocampal stimulus; a preceding stimulus to the amygdala could block this response in two of three tuberoinfundibular cells. These observations provide preliminary electrophysiological analysis of the functional connectivity of hippocampal and amygdala afferents to medial hypothalamic neurons that may underlie the influence of these extrahypothalamic regions on adenohypophyseal secretions.

Action Potentials↗
PubMed1981

[Response of the hypothalamo-corticotropic system to metyrapone in pigeons].

Chronic catheterization and miniature recording device allowed plasma corticosterone (B) and hypothalamic multiunit activity (MUA) to be simultaneously obtained from freely behaving, awake pigeons, before and for 4 hrs after intravenous injection of metyrapone. Injection of vehicle (tartric acid : 100 mg/4 ml/kg) led to MUA and B profiles quite similar to stress-induced responses, i.e., a rapid and sustained rebounding increase in hypothalamic firing rate and, shifted by 5-10 min, in plasma B. These responses were progressively attenuating for 90-120 mn. Metyrapone administration induced first a rapid and short MUA and B increase. Then both parameters drastically decreased near zero for about 2 hrs and were slowly restored to initial values within 3-4 hrs. It is suggested that metyrapone treatment inhibited both peripheral (B synthesis) and central (hypothalamic neurons) levels of the corticotropic axis.

Adrenal Cortex↗
PubMed1980

Adrenocrotical responses to systemic or neurogenic stress and to hypothalamic stimulation in chronically catheterized thalamic pigeons.

Thalamic and intact pigeons were equipped with a chronic arterial catheter and with a miniature electronic device for hypothalamic telestimulation. Chronic catheterization allowed for repetitive blood sampling in freely moving birds subjected to either systemic (ether inhalation) or neurogenic (electrical foot shocks) stress and to electrical stimulation of the hypothalamic corticotropic area. Corticosterone levels were determined by protein binding assay at 2-, then 5- and 10-min intervals, for 100 min. Basal and experimentally modified plasma corticosterone concentrations were not different in thalamic and intact pigeons. Corticosterone profile exhibited episodic increase including three peaks at 12, 35 and 60 min after stress application. Only the first peak of plasma corticosterone appeared after hypothalamic stimulation. It is suggested that extrahypothalamic neuronal networks are responsible for the long-lasting repetitive adrenocorticotropic response to stress, which are not involved in the single response to hypothalamic stimulation itself. Furthermore, such extrahypothalamic neuronal networks shoudl be located at the diencephalic or rhombencephalic level since hemispherectomized pigeons exhibited the same profile of stress-induced episodic hypercorticosteronemia as seen in intact birds.

Adrenal Cortex↗
PubMed1978

Comparison between hypothalamic multiple-unit activity and corticotropic function after bilateral destruction of the hippocampus.

Multiple unit activity (MUA) was recorded from the adrenocorticotropic area (n. posterior medialis hypothalami, PMH) of unrestrained resting pigeons throughout the 24 h period and compared with plasma corticosterone levels (B). Bilateral electrolytic lesions of the hippocampus suppressed diurnal variations of MUA and B. Both parameters were stabilized at a steady high level whereas complete neural isolation of the basal hypothalamus led to stabilized intermediate plasma B level and MUA pattern.

Adrenal Cortex↗
PubMed1978

Does the nucleus raphes participate in the regulation of resting and stress-induced hypothalamic-pituitary-adrenocortical activity in the pigeon?

Extensive multiple electrolytic lesions were placed into the nucleus raphes of the brain stem in the pigeon. Diurnal pituitary-adrenocortical rhythmicity appeared not to be altered and basal plasma corticosterone level remained quite normal in raphe lesioned birds. Electrical stimulations through permanently implanted electrode were delivered in various central nervous structures in unanaesthetized, freely moving pigeons. Stimulations of nucleus raphes and of various parts of formatio reticularis led to a significant rise in plasma corticosterone within 16 to 19 min after the beginning of the stimulating session. Then, plasma B came again to initial level within 15 minutes. Stimulations of the corticotropic area of the hypothalamus (n. posterior medialis hypothalami) and of archistriatum dorsalis induced an early plasma corticosterone increase occurring immediately after the stimulating burst (10 min). Stimulating the n. septum medialis also had an immediate, but reverse (decrease) effect on plasma corticosterone level. Stress-induced pituitary-adrenal cortical activation exhibited a temporal pattern quite similar to that observed after brain stem (n. raphes or formatio reticularis) stimulation. It is suggested that these various limbic and brain stem areas might be involved in some "limbic system-midbrain circuit" with two components : The forebrain component might be involved in the regulation and diurnal modulation of basal hypothalamic-pituitary-adrenocortical function, the brain-stem component interferring with stress-induced responses.

Adrenal Cortex↗
PubMed1976

Comparison between hypothalamic, hippocampal and septal multiple unit activity and basal corticotropic function in unrestrained, unanesthetized resting pigeons.

Multiple unit activity (MUA) was obtained from various forebrain regions in unanesthetized, unrestrained resting pigeons throughout the whole photoperiod and compared with plasma corticosterone levels. The pattern of electrical activity recorded from the adrenocorticotropic area of the hypothalamus showed diurnal variations which paralleled the plasma corticosterone fluctuations during the 24 h photoperiod. Both parameters were low in the late afternoon and the evening and high in the early morning. Hypothalamic activation slightly preceded the peak o corticosteronemia. Conversely, in hippocampal (H) and septal (S) regions, the peak of MUA occurred in phase opposition with respect to the hypothalamic peak, and there was a marked decrease of firing rates at the moment when adrenocorticotropic activation was initiated.

Animals↗
PubMed1976

Multiple unit activity recording in the corticotropic area of the deafferented hypothalamus and corticosteronemia in the pigeon.

10 Diurnal variations in both multiple unit activity and plasma corticosterone level were suppressed after complete neural isolation of the basal hypothalamus in the pigeon. 20 It is suggested that the circadian activity of the hypothalamic pituitary corticotropic unit partially depends upon the inhibiting influence from the hippocampic-septal structures.

Adrenocorticotropic Hormone↗
PubMed1975

[Effect of hemispherectomy on neuroendocrine responses in birds].

In the thalamic pigeon, neurogenic stimuli were still effective in promoting the adreno-cortical activation. The magnitude of the response was as important as in intact birds and was also similar to that obtained after anterior lateral deafferentation of the hypothalamus. Photically induced testis growth was quite normal in hemispherectomized quail. It appears therefore that in birds two kinds of neuroendocrine responses can be induced without any telencephalic participation.

Adrenal Cortex↗
PubMed1975

Adrenal cortical activation induced by hypothalamic stimulation and stress in pigeons bearing ectopic pituitary autografts.

Adrenocorticotropic abilities in basal and stress conditions, and the responsiveness of ectopically-transplanted pituitaries to hypothalamic stimulation were investigated in adult red Carneau pigeons. In birds with pituitary autografts, both electrical stimulation of the hypothalamus and restraint stress elicited a significant increase in the plasma corticosterone level, however these adrenal cortical responses were not so important as those in intact pigeons. Ether stress, which was a very effective stimulus of adrenocortical activity in controls, did not result in any plasma corticosterone elevation in pigeons that had been operated on. Such a decrease in the functional abilities of ectopic adrenocorticotropic cells was interpreted as the result of an impaired hypothalamic control acting via the systemic bloodstream. This hypothesis was corroborated by a moderate reduction in diurnal variations of the plasma corticosterone level in birds with autografts with respect to intact pigeons. Adenohypophysectomized controls did not show any adrenocortical response either to hypothalamic stimulation or to stress application.

Adrenal Cortex↗
PubMed1975

Influence of septal nuclei on basal pituitary-adrenocortical function in birds.

Septal influences on resting adrenocortical activity were tested in the pigeon by electrical stimulation or electrolytic lesions located in either the medical or the lateral septum. Stimulation of the medial septal area in unanesthetized unrestrained pigeons with chronic implants led to a marked decrease in plasma corticosterone. Stimulation of the lateral septal area was not effective in promoting any corticosterone variation. Lesion placement in the nucleus septalis lateralis resulted in a moderate increase in basal corticosteronemia. The elevation in circulating corticosterone was much higher after destruction of the n. septalis medialis and high values were found at every time during the day. Suppression of the diurnal variation in plasma corticosterone with such a high stable level was compared to previous data which were obtained in pigeons after hippocampectomy and after partial anterior or complete deafferentation of the hypothalamus.

Adrenal Cortex↗
PubMed1975

Effects of hypothalamic deafferentation on basal and stress-induced adrenocortical acitivity in the pigeon.

Partial and complete deafferentation of the hypothalamus of the pigeon was performed using a modified Halasz-Pupp microknife. After complete neural isolation the plasma corticosterone level stabilized at a point intermediate between the morning and evening levels found in intact pigeons. No diurnal rhythm was observed and the response to neurogenic stimulus (restraint) was suppressed. Ether stress, however, induced a rise in plasma corticosterone. Posterior deafferentation had no effect on the diurnal corticosterone rhythm but did block the rise normally found after restraint. Anterior deafferentation did not suppress the stress-induced response but provided the cuts were large enough they inhibited the diurnal corticosterone rhythm. It is suggested therefore that the neural afferents to the hypothalamus which are necessary for diurnal fluctuations in pituitary-adrenal function pass through a sector located anteriorly between 45 degrees and 60 degrees on either side of the mod-line while stress-induced adrenocortical activation is triggered through posterior connexions.

Adrenal Cortex↗