Presynaptic NMDA Receptors Mediate IPSC Potentiation at GABAergic Synapses in Developing Rat Neocortex

NMDA receptors are traditionally viewed as being located postsynaptically, at both synaptic and extrasynaptic locations. However, both anatomical and physiological studies have indicated the presence of NMDA receptors located presynaptically. Physiological studies of presynaptic NMDA receptors on neocortical GABAergic terminals and their possible role in synaptic plasticity are lacking.We report here that presynaptic NMDA receptors are present on GABAergic terminals in developing (postnatal day (PND) 12-15) but not older (PND21-25) rat frontal cortex. Using MK-801 in the recording pipette to block postsynaptic NMDA receptors, evoked and miniature IPSCs were recorded in layer II/III pyramidal cells in the presence of AMPA/KA receptor antagonists. Bath application of NMDA or NMDA receptor antagonists produced increases and decreases in mIPSC frequency, respectively. Physiologically patterned stimulation (10 bursts of 10 stimuli at 25 Hz delivered at 1.25 Hz) induced potentiation at inhibitory synapses in PND12-15 animals. This consisted of an initial rapid, large increase in IPSC amplitude followed by a significant but smaller persistent increase. Similar changes were not observed in PND21-25 animals. When 20 mM BAPTA was included in the recording pipette, potentiation was still observed in the PND12-15 group indicating that postsynaptic increases in calcium were not required. Potentiation was not observed when patterned stimulation was given in the presence of D-APV or the NR2B subunit antagonist Ro25-6981.The present results indicate that presynaptic NMDA receptors modulate GABA release onto neocortical pyramidal cells. Presynaptic NR2B subunit containing NMDA receptors are also involved in potentiation at developing GABAergic synapses in rat frontal cortex. Modulation of inhibitory GABAergic synapses by presynaptic NMDA receptors may be important for proper functioning of local cortical networks during development

Length of heat in arabian and andalusian mares

The length of heat in Andalusian and Arabian mares, and the optimum day of breeding in the first postpartum heat, have been studied. In our results the average of all the heat was 5.78 + 1.54 days. No significant diferences have been found between breeds. The high fertility percentage for the postpartum heat has been reached between 11th and 14th day of ter parturition.Se han estudiado las duraciones de los celos, tanto en yeguas paridas como en no pandas dentro y entre las razas española y árabe, así como los días óptimos de cubrición en el primer celo postparto. Nuestros resultados muestran una media de 5,78 + 1,54 días, para el total de todos los celos, y no hay diferencias significativas entre razas. Los porcentajes mas altos de fertilidad en el celo postparto se alcanzan con cubriciones entre el 112 y 142 día después de parir

Plasmatic progesterone values in andalusian and arabian mares during the reproductive cycle

The plasmatic progesterone levels in Arabian and Andalusian mares during the reproductive cycle have been studied. In the partum there is a significant décrease in plasmatic progesterone levels. During the heat these levels are below 2 ng/ml. During the luteinic period, the plasmatic progesterone levels are suprior in the Arabian mares, oscilating between 5.98 and 12.8 ng/mJ in the Arabian and 4.58 and 8.3 ñg/m1 in the Andalusian mares. In the prepartum and partum "clays there is also significant diference between the two breeds. The length of estral and luteinic period are similar in both breeds with average of 21 3 and 16.5 + 2.25 days respectively. The earlier gestacional test by determinatioPS of-plásmatic progesterone levels" between 18th and 21th days post breeding allow us detect the 100 % of non pregnant and the 95.6 % of pregnant mares.Se han estudiado los niveles plasmáticos de progesterona de yeguas españolas y árabes en diferentes fases del ciclo. reproductor. En el día del parto hay un descenso brusco de los niveles plasmáticos de progesterona y éstos, durante el celo, son inferiores a 2 ng/ml. Los niveles plasmáticos de progesterona son significativamente más altos para la raza árabe que para la española, durante la fase luteínica y comienzo de gestación. Oscilan entre 4,58 y 8,3 ng/ml, en yeguas españolas; y entre 5,98 y 12,8 ng/ml, en las árabes. También difieren significativamente las dos razas en el prepartum y en el día del parto. La duración de la fase luteínica es similar en las dos razas (16,5 + 2,25 días) y la duración del ciclo estral puede cifrarse en 21 + 3 días. El diagnóstico precoz de gestación, por determinación de la progesterona plasmática entre los 18-21"días postcubrición, nos permite detectar el 10 % de los animales vacíos y el 96,6 % de los gestantes

Fertility values in andalusian and arabian mares

The influence of age and number of heats in the fertility value of Arabian and Andalusian mares have been studied. The Arabian mares have a whole fertility value 11 % higher than the Andalusian ones. The fertility is low at the begining of the reproductive life increasing with age and having a subsequent decreasing in mares advanced in years. Also the fertility values are higher with the first heat, and decrease, progressiv,e on the following heats. On the post-partum heat the fertili¬ty value was 40 % for the Andalusian and 55 % for the Arabian mares.Se han estudiado los valores de fertilidad de las yeguas de raza española, y árabe, dentro y entre razas, así como la influencia de la edad y el número de celos. Las yeguas árabes son un 11 % más fértiles que las españolas, ya que la fertilidad total en yeguas españolas es del 57,7 %; y en las árabes, del 68,5 %. La fertilidad es menor al comienzo de la vida reproductiva, y se incrementa para volver a descender a edades avanzadas. La fertilidad es más alta en el primer celo y decrece en celos sucesivos. Para el celo post-partum es del 40 % y 55 %, para yeguas españolas y árabes, respectivamente

5-hydroxytryptamine content in total brain and in various central nervous system regions of rats intoxicated with the aqueo

The administration of the aqueous extract of Astragalus lusitanicus to rats, in a dose" corresponding to 45 g wet plant/kg body weight, brougW about the sintomatology of a central nervous system depression that persisted until the animals were sacrificed. The diencephalon and hippocampus content of 5-hydroxytryptamine significantly increased in the intoxicated group with respect to control rats, In total brain, midbrain and Pons-medulla, the 5-hydroxytryptamine levels remained practically unaltered. The results indicate that the aqueous extract of A. lusitanicus containg a substance (s) which modifies the functional activity of the serotonergic system. This effect could be in part responsible for the depression pattern observed in the studied experimental acute intoxication.La administración del extracto acuoso de Astragalus lusitanicus en ratas, en una dosis equivalente a 45 g de planta fresca/kg pv, provocó síntomas característicos de un estado depresivo del sistema nervioso central, que pe•sisitieron hasta que los animales fueron sacrificados. La 5-hidroxitriptamina aumentó significativamente en el grupo intoxicado, respecto al control, en diencéfalo e hipocampo. En bulbo-puente, mesencéfalo y encéfalo total los niveles de dicho neurotransmisor permanecieron prácticamente inalterados. Los resultados indican que el extracto acuoso de A. lusitanicus contiene una sustancia (s) capaz de modificar la actividad funcional del sistema serotoninérgico. Este efecto podría ser en parte responsable del cuadro depresivo observado en la intoxicación aguda experimental estudiada