Ovarian follicular dynamics and plasma steroid concentrations are not significantly different in ewes given intravaginal sponges containing either 20 or 40 mg of fluorogestone acetate.

Although various progestagens are often used to induce and synchronize estrus and ovulation in ruminants, concerns regarding residues are the impetus to develop alternative approaches, including reduced doses of progestagens. Therefore, the objective was to determine whether ovarian function was affected by halving the dose of fluorogestone acetate in intravaginal sponges for synchronizing ovulation in sheep during the physiologic breeding season. Twenty Manchega ewes, 4-6-year-old, were randomly allocated to receive an intravaginal sponge containing either 20mg (P20, n=10) or 40 mg of fluorogestone acetate (P40, n=10). Cloprostenol (125 microg) was given at sponge insertion, and all sponges were removed after 6d. Ovarian follicular dynamics (monitored by daily ultrasonography) and other aspects of ovarian function did not differ significantly between the two groups. Ovulatory follicles (OF) grew at a similar growth rate (r=0.62; P<0.001), with comparable initial and maximum diameters (4.2+/-0.4 to 6.0+/-0.3mm in P20 vs. 4.6+/-0.6 to 5.7+/-0.2 mm in P40, mean+/-S.E.M.). Plasma estradiol concentrations (determined once daily) increased linearly during the 72 h interval after sponge removal (1.3+/-0.1 to 3.3+/-0.1 pg/mL for P20, P<0.005 and 1.4+/-0.1 to 3.1+/-0.2 pg/mL for P40, P<0.005). Ten days after sponge removal, ovulation rates (1.2+/-0.2 for P20 and 1.4+/-0.3 for P40), and plasma progesterone concentrations (3.8+/-0.35 ng/mL for P20 and 3.9+/-0.38 ng/mL for P40) were similar. In conclusion, reducing the dose of fluorogestone acetate from 40 to 20mg did not affect significantly ovarian follicular dynamics or other aspects of ovarian function.

Fisiología humana

En su significado actual, el término fisiología fue usado por vez primera por J. Fernel en 1542, en el sentido de conocimiento y estudiode la naturaleza viva; a partir de entonces el término se aplicó al estudio de la actividades vitales de individuos humanos sanos.la ciencia de la fisiología se conformó a lo largo del siglo XIX, desde el punto de vista experimental y conceptual. En ese siglo se crearon importantes centros para el estudio científico de las funciones de los seres vivos, se publicaron elaborados compendios de los conocimientos fisiológicos de la época y se comenzaron a publicar revistas de la especialidad, muchas de las cuales han llegado hasta nuestros tiempo.

Circadian urinary 6-sulphatoxymelatonin, cortisol excretion and locomotor activity in airline pilots during transmeridian flights.

Airline pilots divided into two groups of age (over and under 50 years) were studied before, during and after westbound (Madrid-Mexico City-Madrid, n = 12) and eastbound (Madrid-Tokyo-Madrid, n = 21) flights. A group of 10 age-matched people staying in Madrid were submitted to the same tests and served as a control group. Changes in urinary 6-sulphatoxymelatonin (6-aMTs) and free cortisol excretion (determined in 6-hr intervals) were measured by radioimmunoassay. Using wrist actigraphy, the circadian locomotor activity rhythm (LAR) was also monitored. Maximal baseline excretion of 6-aMTs occurred between 00:00 and 12:00 hr and maximal excretion of cortisol took place between 6:00 and 12:00 hr in the control group. Analysed globally, older pilots exhibited significantly lower values of 6-aMTs than younger ones. In both flight directions, pilots maintained the pattern of excretion of 6-aMTs, corresponding to baseline. The return flight to Madrid from Mexico and Tokyo coincided with a maximum in 6-aMTs excretion. Pilots kept the cortisol pattern found in the control group, with those over 50 years of age exhibiting significantly lower cortisol values than the younger ones. A 7-hr delay in acrophase of LAR after 2 days in Mexico City was found after cosinor analysis, and similar pre-flight values were found after returning to Madrid. An 8-9-hr acrophase advance of LAR was observed after arriving in Tokyo, with acrophase on the post-return flight day still being advanced 3 4 hr as compared to pre-flight values. Decreases in the amplitude of LAR in older pilots were found at Mexico City, as well as at Tokyo stopover and on post-flight day. Data confirm the occurrence of internal desynchronization in airline crewmembers after transmeridian flights.

Changes in serum growth hormone and prolactin levels, and in hypothalamic growth hormone-releasing hormone, thyrotropin-releasing hormone and somatostatin content, after superior cervical sympathectomy in rats.

After bilateral superior cervical ganglionectomy (SCGx) of adult male rats, norepinephrine (NE) content of the medial basal hypothalamus (MBH) decreased significantly by 39-47% from 16 h to 7 days after surgery. During this time the levels of serum growth hormone (GH) and prolactin (PRL) and of MBH GH-releasing hormone (GRH), thyrotropin-releasing hormone (TRH) and somatostatin were measured by RIA. In sham-operated controls, serum PRL increased and serum GH decreased 16-24 h after surgery, attaining pre-surgical levels later on. In SCGx rats, significantly lower serum GH and PRL and higher MBH GRH and TRH content as compared to controls was observed 16-24 h after surgery, during the wallerian degeneration phase after SCGx. MBH somatostatin concentration decreased in SCGx rats 20 h after surgery. Two injections of the alpha 1-adrenoceptor blocker prazosin 45 and 90 min before sacrifice, alone or together with the beta-blocker propranolol, prevented the changes in MBH hypophysiotropic hormone content, as well as in serum GH and PRL levels, found in SCGx rats 20 h after surgery. Propranolol treatment did not affect hormone levels. Neither drug modified the decrease in MBH NE content observed after SCGx. The results argue in favor of the existence of physiologically relevant projections from superior cervical ganglion neurons to the MBH controlling hypophysiotropic hormone release.

[Possible mechanisms of the interaction between gonadotropins and prolactin in an experimental hyperprolactinemia model]. / Posibles mechanismos de interacción entre gonadotropinas y prolactina en un modelo de hiperprolactinemia experimental.

The effects of grafting one extra pituitary gland beneath the kidney capsule of prepubertal male and female rats on plasma levels and pituitary content of gonadotropins and prolactin (PRL) in the adult age were studied. Further treatments with dopamine agonistic or antagonistic drugs have been performed in grafted and sham operated controls. PRL and gonadotropin values were measured by specific RIA methods using materials provided by NIAMDD. Plasma prolactin levels showed increased values 48 hr after the grafting, and maintained this elevation throughout the whole studied period. These high PRL levels in grafted rats resulted in a significant decrease of plasma LH values over the whole studied period compared with sham operated controls. Surprisingly an elevation of plasma FSH levels was detected in grafted animals, being the increase only significant in the first 3 months after the grafting. No differences could be detected from control values beyond this period. Female rats showed a constant diestrous anovulatory syndrome. Both male and female grafted rats showed diminished plasma LH and FSH responses to the i.p. LHRH administration. After EB administration control female rats showed a pulsatile response of plasma prolactin, FSH and LH with higher levels found in the afternoon. This pulsatility was abolished for PRL, diminished for LH and exaggerated for FSH in grafted animals. Male grafted rats presented a delay in the EB response pattern compared to control rats. Lisuride treatment (DA agonist) eight months after the grafting resulted in a significant reduction to plasma PRL levels. Acutely Lisuride administration restored LH response to LHRH together with a significant increase in the number of estrus in female rats. Chronic administration of the drug resulted in decreased plasma LH values not only in controls but also in grafted animals, together with an impaired response to LHRH and a significant increase in the number of diestrus in control and experimental rats. On the other hand, both acute or chronic Metoclopramide administration (DA antagonist drug) significantly increased plasma prolactin levels in control and grafted rats. This increase was accompanied by an elevation in the number of estrus in grafted female rats together with a restored LH response to LHRH higher to those observed in control female rats. These data suggest that prolactin influence on gonadotropin secretion and fertility could be mediated by a modification on dopamine secretion.

Posibles mechanismos de interacción entre gonadotropinas y prolactina en un modelo de hiperprolactinemia experimental. / [Possible mechanisms of the interaction between gonadotropins and prolactin in an experimental hyperprolactinemia model]

The effects of grafting one extra pituitary gland beneath the kidney capsule of prepubertal male and female rats on plasma levels and pituitary content of gonadotropins and prolactin (PRL) in the adult age were studied. Further treatments with dopamine agonistic or antagonistic drugs have been performed in grafted and sham operated controls. PRL and gonadotropin values were measured by specific RIA methods using materials provided by NIAMDD. Plasma prolactin levels showed increased values 48 hr after the grafting, and maintained this elevation throughout the whole studied period. These high PRL levels in grafted rats resulted in a significant decrease of plasma LH values over the whole studied period compared with sham operated controls. Surprisingly an elevation of plasma FSH levels was detected in grafted animals, being the increase only significant in the first 3 months after the grafting. No differences could be detected from control values beyond this period. Female rats showed a constant diestrous anovulatory syndrome. Both male and female grafted rats showed diminished plasma LH and FSH responses to the i.p. LHRH administration. After EB administration control female rats showed a pulsatile response of plasma prolactin, FSH and LH with higher levels found in the afternoon. This pulsatility was abolished for PRL, diminished for LH and exaggerated for FSH in grafted animals. Male grafted rats presented a delay in the EB response pattern compared to control rats. Lisuride treatment (DA agonist) eight months after the grafting resulted in a significant reduction to plasma PRL levels. Acutely Lisuride administration restored LH response to LHRH together with a significant increase in the number of estrus in female rats. Chronic administration of the drug resulted in decreased plasma LH values not only in controls but also in grafted animals, together with an impaired response to LHRH and a significant increase in the number of diestrus in control and experimental rats. On the other hand, both acute or chronic Metoclopramide administration (DA antagonist drug) significantly increased plasma prolactin levels in control and grafted rats. This increase was accompanied by an elevation in the number of estrus in grafted female rats together with a restored LH response to LHRH higher to those observed in control female rats. These data suggest that prolactin influence on gonadotropin secretion and fertility could be mediated by a modification on dopamine secretion.