Christine Buckley | PubMed Health

PubMed2004

Induced ovulation and egg deposition in the direct developing anuran Eleutherodactylus coqui.

This study investigates ovulation and egg deposition behaviors in the anuran Eleutherodactylus coqui from Puerto Rico in response to stimulation with gonadotropin and gonadotropin releasing hormones. Five hormones were tested by injection over a range of doses, including mammalian LHRH, avian LHRH, fish LHRH, D-Ala6, des-Gly10 ethylamide LHRH and hCG. We report a low level of ovulation and egg deposition in response to all hormones, with the most complete and consistent results from the non-natural D-Ala6, des-Gly10 ethylamide LHRH derivative. To confirm the viability of eggs produced in this manner we performed in vitro fertilization experiments that resulted in the development of normal frogs. Reproductive behaviors in E. coqui are apparently not controlled by a mammalian form of LHRH as reported in other common laboratory anuran species. D-Ala6, des-Gly10 ethylamide LHRH induces ovulation and deposition of mature and fertilizable eggs in E. coqui.

Animals↗

PubMed2002

Systemic vascular endothelial cell dysfunction in normal pressure glaucoma.

AIM: Vascular risk factors, and particularly vasospasm, are thought to play a part in the pathogenesis of normal pressure glaucoma (NPG). This study aimed to determine whether the function of systemic resistance arteries was altered in patients with NPG. METHODS: Contractile and relaxant function was assessed in arteries dissected from gluteal fat biopsies (11 NPG, 12 control) using small vessel myography. RESULTS: Responses to K(+) and noradrenaline were similar in patients and controls and were unaffected by endothelial removal. In contrast, responses to 5-hydroxytryptamine (5-HT; pD(2); 7.29 (SD 0.16) v 6.66 (0.19); p=0.03) and endothelin-1 (ET-1; pD(2), 9.12 (0.10) v 8.72 (0.13); p=0.03) were enhanced in arteries from patients with NPG. Removal of the endothelium enhanced responses to 5-HT (pD(2), 6.66 (0.19) v. 7.66 (0.08); p=0.003) and ET-1 (pD(2), 8.72 (0.13) v. 9.66 (0.39); p=0.02) in control arteries but not in those from patients. ET-1 mediated contraction in control and patient arteries was reduced in the presence of (10(-5) M) nifedipine. Endothelium dependent and independent relaxation was not impaired in arteries from patients. CONCLUSIONS: This study has identified dysfunction of the systemic vascular endothelial cell in patients with normal pressure glaucoma. The vascular endothelium modulates contractile responses to 5-HT and ET-1 in human subcutaneous resistance arteries but this effect is lost in patients with NPG, indicating a selective defect in agonist mediated release of endothelium derived vasodilators. Selective antagonists of 5-HT and ET-1 may, therefore, help to prevent vasospasm in patients with NPG.

Adult↗