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In the bitch, progression from early to late anoestrus is characterized by a higher amplitude and a larger number of gonadotrophin-releasing hormone (GnRH) pulses generated by the hypothalamus, an increase in the sensitivity of the pituitary to GnRH, and an increase in ovarian responsiveness to gonadotrophins. An increase in basal plasma follicle-stimulating hormone (FSH) concentration is a critical event required for initiation of folliculogenesis. A period of increased luteinizing hormone pulsatility has been reported shortly before the onset of pro-oestrus. Apart from these changes in the hypothalamic-pituitary-ovarian axis, there is also involvement of dopaminergic influences in the initiation of a new follicular phase in the bitch. Administration of the dopamine-agonists bromocriptine and cabergoline shortens the anoestrus and is associated with a decrease in the plasma prolactin concentration, suggesting that the shortened anoestrus is the result of suppression of prolactin secretion. Yet, the anoestrus is not shortened in bitches treated with metergoline, a drug, which in a low dosage lowers the plasma prolactin concentration via a serotonin-antagonistic pathway. In addition, under physiological conditions low plasma prolactin concentrations are found during the entire anoestrus. Furthermore, a low dosage of bromocriptine, insufficient to cause a decrease in the plasma prolactin concentration, prematurely induces folliculogenesis. These observations indicate that not the decrease in the plasma prolactin concentration, but another dopamine-agonistic influence plays a critical role in the transition to a new follicular phase. The dopamine-agonist induced shortening of the anoestrus is associated with a rapid rise in the basal plasma FSH concentration, similar to what is observed during the physiological late anoestrus. This observation underlines the importance of an increase in the circulating plasma FSH concentration in the initiation of folliculogenesis in the bitch. 相似文献
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Detection and localization of regucalcin in spermatozoa of water buffalo (Bubalus bubalis): A calcium‐regulating multifunctional protein 
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下载免费PDF全文 H Pillai AM Shende MS Parmar J Thomas HS Kartha G Taru Sharma SK Ghosh SK Bhure 《Reproduction in domestic animals》2017,52(5):865-872
Regucalcin (RGN) is a calcium‐regulating, anti‐apoptotic, antioxidative and antiproliferative multifunctional protein predominantly seen in liver and kidney. All these functions are very crucial during spermatogenesis and sperm maturation process until fertilization of the ovum. Although many studies have reported the wide distribution of regucalcin in the male reproductive tract of the rat, human and bovine, its presence in spermatozoa is yet to be demonstrated wherein calcium has a pivotal role in the transport, capacitation, acrosomal reaction and further fusion with ova. Here, we detected the expression of regucalcin mRNA and protein in buffalo spermatozoa using real‐time PCR and Western blot, respectively. The study detected two new regucalcin isoforms of 44 kDa and 48 kDa size along with the reported 34‐kDa, 28‐kDa and 24‐kDa isoforms, wherein the 34‐kDa isoform was found to be membrane associated in spermatozoa. Further, immunocytochemistry study localized the regucalcin protein in the acrosomal region of the caudal and ejaculated buffalo spermatozoa while it was detected in both cytoplasm and acrosomal region of testicular spermatozoa. This discovery of RGN in spermatozoa and localization in the acrosomal region will help to focus researchers to see its role in calcium‐related functions like capacitation, acrosomal reaction and membrane fusion. Overall, regucalcin may be a new fertility marker in buffalo and can be utilized for infertility treatments. 相似文献
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Seeram NP Henning SM Niu Y Lee R Scheuller HS Heber D 《Journal of agricultural and food chemistry》2006,54(5):1599-1603
The health benefits associated with tea consumption have resulted in the wide inclusion of green tea extracts in botanical dietary supplements, which are widely consumed as adjuvants for complementary and alternative medicines. Tea contains polyphenols such as catechins or flavan-3-ols including epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate (EGCG), as well as the alkaloid, caffeine. Polyphenols are antioxidants, and EGCG, due to its high levels, is widely accepted as the major antioxidant in green tea. Therefore, commercial green tea dietary supplements (GTDS) may be chemically standardized to EGCG levels and/or biologically standardized to antioxidant capacity. However, label claims on GTDS may not correlate with actual phytochemical content or antioxidant capacity nor provide information about the presence and levels of caffeine. In the current study, 19 commonly available GTDS were evaluated for catechin and caffeine content (using high-performance liquid chromatography) and for antioxidative activity [using trolox equivalent antioxidant capacity (TEAC) and oxygen radical antioxidant capacity (ORAC) assays]. Product labels varied in the information provided and were inconsistent with actual phytochemical contents. Only seven of the GTDS studied made label claims of caffeine content, 11 made claims of EGCG content, and five specified total polyphenol content. Caffeine, EGCG, and total polyphenol contents in the GTDS varied from 28 to 183, 12-143, and 14-36% tablet or capsule weight, respectively. TEAC and ORAC values for GTDS ranged from 187 to 15340 and from 166 to 13690 mumol Trolox/g for tablet or capsule, respectively. The antioxidant activities for GTDS determined by TEAC and ORAC were well-correlated with each other and with the total polyphenol content. Reliable labeling information and standardized manufacturing practices, based on both chemical standardization and biological assays, are recommended for the quality control of botanical dietary supplements. 相似文献
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Seeram NP Adams LS Zhang Y Lee R Sand D Scheuller HS Heber D 《Journal of agricultural and food chemistry》2006,54(25):9329-9339
Berry fruits are widely consumed in our diet and have attracted much attention due to their potential human health benefits. Berries contain a diverse range of phytochemicals with biological properties such as antioxidant, anticancer, anti-neurodegerative, and anti-inflammatory activities. In the current study, extracts of six popularly consumed berries--blackberry, black raspberry, blueberry, cranberry, red raspberry and strawberry--were evaluated for their phenolic constituents using high performance liquid chromatography with ultraviolet (HPLC-UV) and electrospray ionization mass spectrometry (LC-ESI-MS) detection. The major classes of berry phenolics were anthocyanins, flavonols, flavanols, ellagitannins, gallotannins, proanthocyanidins, and phenolic acids. The berry extracts were evaluated for their ability to inhibit the growth of human oral (KB, CAL-27), breast (MCF-7), colon (HT-29, HCT116), and prostate (LNCaP) tumor cell lines at concentrations ranging from 25 to 200 micro g/mL. With increasing concentration of berry extract, increasing inhibition of cell proliferation in all of the cell lines were observed, with different degrees of potency between cell lines. The berry extracts were also evaluated for their ability to stimulate apoptosis of the COX-2 expressing colon cancer cell line, HT-29. Black raspberry and strawberry extracts showed the most significant pro-apoptotic effects against this cell line. The data provided by the current study and from other laboratories warrants further investigation into the chemopreventive and chemotherapeutic effects of berries using in vivo models. 相似文献
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Effect of cumulus cells and sperm concentration on fertilization and development of pig oocytes 下载免费PDF全文
下载免费PDF全文 Effect of sperm concentrations and cumulus cells (CCs) on porcine IVF was re‐evaluated using current improved IVM and IVC system. Our results showed that both CCs and sperm concentration had significant effect on penetration rate, frequency of polyspermy and embryonic development. The best IVF results were obtained with oocytes with CCs fertilized with 0.5 × 105 sperm/ml. Such an IVP system works on both sow and gilt oocytes. 相似文献
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Antinociceptive effect of buprenorphine and evaluation of the nociceptive withdrawal reflex in foals 下载免费PDF全文
下载免费PDF全文 Åse I Risberg Claudia Spadavecchia Birgit Ranheim Eli HS Hendrickson Andreas Lervik Henning A Haga 《Veterinary anaesthesia and analgesia》2015,42(3):329-338
ObjectiveTo elicit and evaluate the NWR (nociceptive withdrawal reflex) in 2 and 11 day old foals, to investigate if buprenorphine causes antinociception and determine if the NWR response changes with increasing age. The effect of buprenorphine on behaviour was also evaluated.Study designProspective, experimental cross-over trial.AnimalsNine Norwegian Fjord research foals.MethodsBuprenorphine, 10 μg kg−1 was administered intramuscularly (IM) to the same foal at 2 days and at 11 days of age. The NWR and the effect of buprenorphine were evaluated by electromyograms recorded from the left deltoid muscle following electrical stimulation of the left lateral palmar nerve at the level of the pastern. Mentation, locomotor activity and respiratory rate were recorded before and after buprenorphine administration.ResultsWe were able to evoke the NWR and temporal summation in foals using this model. Buprenorphine decreased the root mean square amplitude following single electrical stimulation (p < 0.001) in both age groups, and increased the NWR threshold following single electrical stimulation in 2 day old foals (p = 0.0012). Repeated electrical stimulation at 2 Hz was more effective to elicit temporal summation compared to 5 Hz (p < 0.001). No effect of age upon the NWR threshold was found (p = 0.34). Sedation when left undisturbed (11 occasions), increased locomotor activity when handled (9 occasions) and tachypnea (13 occasions) were common side-effects of buprenorphine.Conclusion and clinical relevanceThese findings indicate that buprenorphine has antinociceptive effect in foals. Opioid side effects often recognized in adult horses also occur in foals. 相似文献
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