Functional activity of human ZP3 primary sperm receptor resides toward its C-terminus.

Zona pellucida glycoprotein 3 (ZP3) has been ascribed as a putative primary sperm receptor during fertilization in humans. Herein, attempts have been made to delineate the functional domain of human ZP3. ZP3 has been cloned and expressed in a baculovirus expression system as N-terminal fragments (amino acid [aa] residues 1-175 [pAc-ZP3(1-175 aa)] and 23-175 [pBg-ZP3(23-175 aa)]) and as C-terminal fragments (aa residues 214-305 [pBg-ZP3(214-305 aa)] and 214-348 [pBg-ZP3(214-348 aa)]). ZP3 encompassing both N- and C-terminal fragments corresponding to aa residues 1-370 (pAc-ZP3([1-370 aa])) has also been expressed. Lectin-binding analysis with these recombinant proteins revealed the presence of N- and O-linked glycosylation. Significant induction of acrosomal exocytosis was observed when capacitated sperm were incubated with pBg-ZP3(214-348 aa), pBg-ZP3(214-305 aa), and pAc-ZP3(1-370 aa) (P < 0.05), whereas incubation with pAc-ZP3(1-175 aa) and pBg-ZP3(23-175 aa) failed to do so under similar experimental conditions. However, N- and C-terminal fragments labeled with fluorescein isothiocyanate revealed binding to the anterior head of capacitated human spermatozoa. Escherichia coli-expressed ZP3 C-terminal fragments and chemically deglycosylated pBg-ZP3(214-348 aa) failed to induce a significant (P > 0.05) increase in acrosomal exocytosis, suggesting the relevance of glycosylation in imparting functional activity to ZP3 C-terminal fragments. pBg-ZP3(214-348 aa)-mediated induction of acrosomal exocytosis is regulated by G(i) protein, extracellular calcium, GABA(A) [gamma aminobutyric acid (A)] receptor-mediated Cl(-) channel, and T-type voltage-operated calcium channels. Taken together, the results of these studies suggest that the functional activity of human ZP3 resides in its C-terminal domain.

Cardioprotection from ischemia and reperfusion injury by Withania somnifera: a hemodynamic, biochemical and histopathological assessment.

The efficacy of Withania somnifera (Ws) to limit myocardial injury after ischemia and reperfusion was explored and compared to that of Vit E, a reference standard known to reduce mortality and infarct size due to myocardial infarction. Wistar rats (150-200 g) were divided into six groups and received orally saline (sham, control group), Ws-50/kg (Ws control and treated group) and Vit E-100 mg/kg (Vit E control and treated group) respectively for 1 month. On the 31st day, rats of the control, Vit E and Ws treated groups were anesthetized and subjected to 45 min occlusion of the LAD coronary artery followed by 60 min reperfusion. Hemodynamic parameters: systolic, diastolic and mean arterial pressure (SAP, DAP, MAP), heart rate (HR), left ventricular end diastolic pressure (LVEDP), left ventricular peak (+)LVdP/dt and (-)LVdP/dt were monitored. Hearts were removed and processed for histopathological and biochemical studies: Myocardial enzyme viz, creatin phosphokinase (CPK), and antioxidant parameters: malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx) were estimated. Postischemic reperfusion produced significant cardiac necrosis, depression of left ventricular functions (MAP, LVEDP, (+) and (-)LVdP/dt) and a significant fall in GSH (p < 0.01), SOD, CAT (p < 0.05), LDH and CPK (p < 0.01) as well as an increase in MDA level (p < 0.05) in the control group rats as compared to sham group. The changes in levels of protein and GPx was however, not significant. Ws and Vit E favorably modulated most of the hemodynamic, biochemical and histopathological parameters though no significant restoration in GSH, MAP (with Vit E) were observed. Ws on chronic administration markedly augmented antioxidants (GSH, GSHPx, SOD, CAT) while Vit E did not stimulate the synthesis of endogenous antioxidants compared to sham. Results indicate that Ws significantly reduced myocardial injury and emphasize the beneficial action of Ws as a cardioprotective agent.