Serotoninergic mechanisms in ovarian cycle (author's transl)]

Influence of 5-HT on the rat follicle rupture mechanism was studied by the administration of p-clorophenyl-alanine (p-CPA) (300 mg/kg) at different stages of the ovarian cycle. The ovarian cycle of treated rats was subject of investigation, as well as the histology of tubes and ovaries. Administration of p-CPA at 10 hours of metestrus phase induces an inhibition of ovulation. Predominant diestrus phases in the ovarian cycle and luteinitation of ovaries suggested an increase in progesterone secretion probably owed to a correspondingly greater prolactine secretion. Adequate 5-HT levels in central structures proved to necessary for normal ovulation.     

Posterior hypothalamus action on gastric secretion (author's transl)]

Three groups of cats with surgically created total gastric pouches were employed in this experiment. They were divided as follows: in one group the innervation of the pouch was left intact; in another group the symphathetic innervation of the pouch was removed; and in the third group the pouch was completely denervated. It was seen that an infusion of histamine induced gastric secretion in all three groups. And when the secretion became constant it proved to be less acidic and more abundant in the sympathectomized group and also in the group that had suffered complete denervation. It was observed now that stimulating the posterior hypothalamus of the innervated group produced, in all of the cats, a decrease in the amount of acid secreted per unit of time. Consequently, it was seen that a symphathectomy did not eliminate the gastric effects produced when the posterior hypothalamus was stimulated. Specifically, stimulation of the posterior hypothalamus produced an increase in the amount of secretion rather than a decrease. The increase produced in these animals can be shown not to be due to irradiation of the anterior hypothalamus as the same response is obtained when a symphathectomy is combined with a vagotomy. It is, therefore, believed that it may be concluded that the Posterior hypothalamus does not produce its effect exclusively through its nervous pathways. It is believed its effect may possibly be mediated by an unknown substance liberated upon stimulation which then reaches the stomach by way of its blood supply.     

Pattern stimulation and action potential of frog skin (author's transl)]

Experiments were carried out to investigate the relationship between the pattern of stimulus of efferent or afferent nerve and the size of action potential of frog's skin. Two kinds of preparations were used: the excised nerve skin preparation and the spinal preparation. In the range of moderate intervals of stimuli, the size of skin action potential of the nerve-skin preparation became larger with the increase of number of stimuli, (i) during a definite period of stimulation with various frequencies, or (ii) during various long periods of stimulation with constant frequency. The size of potential depended not only on number of stimuli but also on their interval. The latter property may be called pattern-sensitive. In some state of preparation the size of potential evoked by a constant number of stimuli was nearly constant, being independent from stimulus frequencies, that is, pattern insensitive. Both kinds of results were obtained in cases of the spinal preparation. Michaelis-Menten's equation could be applied to describe the relation between the size of potential and the number of stimuli. However, there was no reason to interprete this relation with a simple concentration-effect relationship. Another hypothesis was then testoned on the supposition that the response is composed of sequentially superposed unitary processes each of which was promptly evoked by each stimulus and decayed exponentially. The calculated response curve reasonably fit with the observed data. Slower processes commonly called accomodation were excluded from the present discussion and only the effect of relatively short period of stimulation was examined.