Ed Hoffmann Madureira

Effects of acute and long-term domperidone treatment on prolactin and gonadal hormone levels and sexual behavior of male and female rats

Domperidone (DOMP), a dopamine D2 blocker that is unable to cross the blood-brain barrier, is an experimental tool used to induce hyperprolactinemia. Acute and long-term DOMP administration was tested in male and female rats for its effects on sexual behavior and plasma gonadal hormone levels. DOMP (4.0 mg/kg) was injected I.P. either acutely or daily for 30 days. Acute treatment failed to modify any behavioral parameter observed. The 5-day treatment stimulated and the 30-day treatment failed to inhibit sexual behavior of male rats. Serum testosterone levels were significantly reduced after 30 days of treatment in male rats. The 30-day treatment also inhibited sexual behavior and enhanced plasma progesterone levels in ovariectomized and intact female rats, respectively. The present results may be due to DOMP-induced long-term hyperprolactinemia. Alternatively, blockade of dopamine peripheral receptors induced by this treatment may also be responsible for the behavioral changes reported here. Moreover, these data suggest that female rats are more susceptible than males to the behavioral effects of long-term hyperprolactinemia.

Development of poly(lactic acid) nanostructured membranes for the controlled delivery of progesterone to livestock animals

Solution blow spinning (SBS) is a novel technology feasible to produce nanostructured polymeric membranes loaded with active agents. In the present study, nanofibrous mats of poly(lactic acid) (PLA) loaded with progesterone (P4) were produced by SBS at different P4 concentrations. The spun membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). The in vitro releasing of P4 was evaluated using high-performance liquid chromatography (HPLC). Interactions between progesterone and PLA were confirmed by rheological measurements of the PLA/P4 solutions and in the spun mats by microscopy (SEM), thermal (DSC) and spectral (FTIR) analyses. SEM micrographs provided evidences of a smooth and homogeneous structure for nanostructured membranes without progesterone crystals on fiber surface. FTIR spectroscopy indicated miscibility and interaction between the ester of PLA and the ketone groups of the P4 in the nanofibers. X-ray analysis indicated that the size of PLA crystallites increased with progesterone content. Finally, by in vitro release experiments it was possible to observe that the progesterone releasing follows nearly first-order kinetics, probably due to the diffusion of hormone into PLA nanofibers.

Existem relações entre tamanho e morfoecogenicidade do corpo lúteo detectados pelo ultra-som e os teores de progesterona plasmática em receptoras de embriões eqüinos?

O corpo luteo (CL) e a glândula produtora de progesterona (P4), hormonio cuja secrecao continua e essencial para o inicio e a manutencao da gestacao em femeas equinas, e, consequentemente, para a aplicabilidade de inumeras biotecnicas de reproducao. Considerando-se a importância do CL para a manutencao de uma gestacao normal e suas caracteristicas anatomofisiologicas, objetivou-se determinar por ultra-sonografia (US) o tamanho e a morfoecogenicidade (ME) do CL em receptoras de embrioes equinos desde a ovulacao (D0) ate nove dias apos (D9), bem como os niveis plasmaticos de P4 produzida no mesmo periodo. Para tanto, 57 eguas receptoras de um programa de transferencia de embrioes foram examinadas diariamente por US transretal desde a primeira deteccao dos sinais de estro ate o D9. A cada exame, os CL foram mensurados e sua ME registrada segundo escore de 1 a 6 (1=anecoico; 6=hiperecoico). Amostras de sangue foram colhidas diariamente e a P4 dosada por radioimunoensaio. O diagnostico de gestacao foi realizado por US aos 13 e 25 dias apos a ovulacao. Houve uma tendencia de os corpos luteos apresentarem ME crescente (de 1 a 5) desde o dia da ovulacao ate o D9. Os niveis de P4 foram < 2,16 ng/ml ate o D3, com consequente elevacao e manutencao em niveis de diestro entre D4 e D9 (3,41 a 4,33 ng/ml). O tamanho luteinico nao diferiu, com excecao das medias extremas durante o periodo (D2 = 31,54 mm versus D8 = 25,95mm; p < 0,05). Assim, o aumento da ME media dos CLs avaliados por US e acompanhado por aumento na concentracao plasmatica de P4 em receptoras de embrioes, mas este evento parece nao ser dependente do tamanho da glândula luteinica. Nao existe diferenca na ME, no tamanho dos corpos luteos, nem nos niveis de P4 circulante do D0 ao D9 em receptoras de embrioes equinos que se tornaram gestantes ou nao apos a transferencia de embrioes.

Follicle and corpus luteum size and vascularity as predictors of fertility at the time of artificial insemination and embryo transfer in beef cattle

Two ultrasound based fertility prediction methods were tested prior to embryo transfer (ET) and artificial insemination (AI) in cattle. Female bovines were submitted to estrous synchronization prior to ET and AI. Animals were scanned immediately before ET and AI procedure to target follicle and corpus luteum (CL) size and vascularity. In addition, inseminated animals were also scanned eleven days after insemination to target CL size and vascularity. All data was compared with fertility by using gestational diagnosis 35 days after ovulation. Prior to ET, CL vascularity showed a positive correlation with fertility, and no pregnancy occurred in animals with less than 40% of CL vascularity. Prior to AI and also eleven days after AI, no relationship with fertility was seen in all parameters analyzed (follicle and CL size and vascularity), and contrary, cows with CL vascularity greater than 70% exhibit lower fertility. In inseminated animals, follicle size and vascularity was positive related with CL size and vascularity, as shown by the presence of greater CL size and vascularity originated from follicle with also greater size and vascularity. This is the first time that ultrasound based fertility prediction methods were tested prior to ET and AI and showed an application in ET, but not in AI programs. Further studies are needed including hormone profile evaluation to improve conclusion.

Sincronização do estro em fêmeas bovinas da raça Nelore (Bos taurus indicus) com o uso de acetato de melengestrol associado ou não à prostaglandina F2alfa

This study was conducted to determine the efficacy of melengestrol acetate (MGA) with or without prostaglandin F2a (PG) in synchronizing estrus in Zebu females (Nelore - Bos taurus indicus). Five hundred and forty-eight cows and heifers were allotted to one of three groups by age, body condition score, sex of calf and days postpartum. Group 1 served as a nonsynchronized control (n = 119) and cows were fed a protein mineral salt carrier without MGA, animals in group 2 (n = 219) were fed 0.5 mg MGA/head/day, for 14 days, and group 3 (n = 210) animals were fed 0.5 mg MGA/head/day for 14 days and were injected i.m. with 25 mg PG, 17 days after the last day of MGA feeding. Cows and heifers were artificially inseminated 12 h after the detection of estrus. The MGA/PG and MGA systems induced synchronized estrus and enabled more cows to become pregnant early in the breeding season compared with nonsynchronized control cows that were inseminated during spontaneous estrus (group 1 = 17.65% vs group 2 = 27.40%; group 3 = 31.90%). In this respect, PG injection caused a larger number of 5 day estrus responses in the MGA/PG group, greatly facilitating the use of AI.