Effects of vaginal stimulation on hypothalamic single units in unanesthetized rabbits

Résumé Certains neurones hypothalamiques présentent dans la demi-heure qui suit une stimulation vaginale des modifications de leur décharge spontanée indépendantes de l'état de vigilance de l'animal. Ces variations pourraient être en rapport avec les mécanismes nerveux de l'ovulation provoquée chez la Lapine.

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We are very grateful to Dr. J. N.Hayward, Department of Anatomy, University of California, Los Angeles, for his constructive criticisms.     

The uptake of35S by hypothalamic and neurohypophysial proteins following intraventricular injection ofl-cysteine-35S-hydrochloride in rats dehydrated and reserpinized

Summary In rats dehydrated for 48 h and injected intraventricularly withl-cysteine-³⁵S-hydrochloride, the specific activity of TCA-precipitable material, both in the hypothalamus and neurohypophysis, was found to diminish under reserpine treatment.     

Baroreceptor and sympathetic responses to acebutolol, a beta 1-adrenoceptor-blocking agent, in rabbits.

Baroreceptor activity was increased after i.v. infusion of acebutolol in rabbits with an intact circulation, and in rabbits with a total cardiopulmonary by-pass. In rabbits with an intact circulation, renal nerve activity was reduced.     

The uptake of 35S by hypothalamic and neurohypophysial proteins following intraventricular injection of L-cysteine-35S-hydrochloride in rats dehydrated and reserpinized.

In rats dehydrated for 48 h and injected intraventricularly with L-cysteine-35S-hydrochloride, the specific activity of TCA-precipitable material, both in the hypothalamus and neurohypophysis, was found to diminish under reserpine treatment.     

Influence of repeated prazosin administration on cardiovascular responses in rats and rabbits

Prazosin was injected i.v. at a dose of 50 g/kg every 2 h for 8 h in conscious rats. Its hypotensive action significantly declined. A similar effect was also observed in rabbits pretreated with prazosin (40 g/kg, i.v.) every 1 h for 4 h. In prazosin-treated rabbits, the total peripheral resistance became less responsive to phentolamine stimulation. Repeated prazosin administration abolished its ability to block receptors in a model of anococcygue muscle contraction after noradrenaline (NA) stimulation. The -adrenoceptors in anococcygue muscle exhibited lower pD₂ to NA and lower pA₂ to prazosin in prazosin-treated rats. The results demonstrate that repeated prazosin administration reduces the effectiveness of -adrenoceptors blockers.     

The influence of ambient temperature on thermoregulatory responses to intraventricularly injected monoamines in sheep,goats and rabbits

Zusammenfassung Zur Erklärung der Effekte auf die Thermoregulation in Schafen, Ziegen und Kaninchen bei verschiedenen Umwelttemperaturen von intraventrikulären Injektionen von Noradrenalin (NA) und 5-Hydroxytryptamin (5-HT) wurde ein einfaches Neuronenmodell vorgeschlagen. Diese Monoamine entfalten nicht in allen Situationen eine reziproke Wirkung. 5-HT führt zu einem Anstieg des Wärmeverlustes und einer Hemmung der Wärmebildung. NA hemmt sowohl Wärmeverlust wie auch Wärmebildung 19.     

Baroreceptor and sympathetic responses to acebutolol,a 646-1646-1646-1agent,in rabbits

Summary Baroreceptor activity was increased after i.v. infusion of acebutolol in rabbits with an intact circulation, and in rabbits with a total cardiopulmonary by-pass. In rabbits with an intact circulation, renal nerve activity was reduced.We wish to thank Mrs H. Bodard and Mrs F. Raimbault for their technical collaboration and Specia Laboratories for supplying acebutolol. This work was supported by a grant from INSERM (ATP No. 15.75.38).     

Respiratory responses in heat-exposed rabbits: Inhibition of tachypnoea offset by increase in tidal volume

Summary Rabbits in which thermal panting has been inhibiting by previous cold exposure or by water deprivation respond to a raised ambient temperature with an increase in tidal volume. By so doing, they are able to maintain a minute volume appropriate to their thermoregulatory requirements.     

Gonadotrophic activity in hypothalamic extracts

Résumé Si l'on administre à des rats stériles par testostérone des extraits hypothalamiques de mouton préparés suivant la technique deGuillemin, on déclenche l'apparition des corps jaunes aussi bien chez les rats entiers que chez les animaux privés d'hypophyse. Ces extraits ont une activité gonadotrophique intrinsèque.     

The nature of posterior hypothalamic projections to cardiorespiratory centers in the brainstem

Summary Focal electrical stimulation of the midlateral posterior hypothalamus in the rat produces rapid shallow respiration accompanied by a rise in arterial blood pressure. Stimulation of presumably intrinsic neurons only by glutamate induces slower deeper respiration associated with a fall in blood pressure.     

The nature of posterior hypothalamic projections to cardiorespiratory centers in the brainstem

Focal electrical stimulation of the midlateral posterior hypothalamus in the rat produces rapid shallow respiration accompanied by a rise in arterial blood pressure. Stimulation of presumably intrinsic neurons only by glutamate induces slower deeper respiration associated with a fall in blood pressure.     

Response due to 0 somatic antigen ofShigella dysenteriae in rabbits

Zusammenfassung Hochgereinigtes Antigen vonShigella dysenteriae bewirkte eine signifikante Temperatursteigerung in Kaninchen.     

Estrogen binds to hypothalamic nuclei of androgen-insensitive (tfm) rats

Summary Androgen-insensitive (tfm) rats possess a nuclear-estrogen binding system in the brain that is similar to that of wild-type control males. In these mutant rats, radiolabeled estradiol was bound predominantly to hypothalamic nuclei and this binding was of limited capacity.This research was supported by grants Nos HD-13957 and HD-14726 from the National Institute of Child Health and Human Development.     

Reserpine prevents goldthioglucose hypothalamic lesions in mice

Summary In reserpinized mice the occurrence of goldthioglucose hypothalamic lesions was significantly lower than in control mice. Some protection was also conferred by serotonin-receptor blockers and by treatment with nialamide+DL--methyldopa, but the protective effect of reserpine was not reversed by serotonergic and dopaminergic agonists, alone or in combination, nor by insulin.     

Effect of estrogens on infection of rabbits with cattle plague virus previously administered to rabbits]

The Rabbit bovipest virus selectively destroys the lymphoid B line in the Rabbit. Estrogens inhibit this destruction when they are administered before the infection which leads are to think that they act on membrane sites of the lymphocytes.