Relaxin's induction of metalloproteinases is associated with the loss of collagen and glycosaminoglycans in synovial joint fibrocartilaginous explants

Diseases of specific fibrocartilaginous joints are especially common in women of reproductive age, suggesting that female hormones contribute to their etiopathogenesis. Previously, we showed that relaxin dose-dependently induces matrix metalloproteinase (MMP) expression in isolated joint fibrocartilaginous cells. Here we determined the effects of relaxin with or without β-estradiol on the modulation of MMPs in joint fibrocartilaginous explants, and assessed the contribution of these proteinases to the loss of collagen and glycosaminoglycan (GAG) in this tissue. Fibrocartilaginous discs from temporomandibular joints of female rabbits were cultured in medium alone or in medium containing relaxin (0.1 ng/ml) or β-estradiol (20 ng/ml) or relaxin plus β-estradiol. Additional experiments were done in the presence of the MMP inhibitor GM6001 or its control analog. After 48 hours of culture, the medium was assayed for MMPs and the discs were analyzed for collagen and GAG concentrations. Relaxin and β-estradiol plus relaxin induced the MMPs collagenase-1 and stromelysin-1 in fibrocartilaginous explants – a finding similar to that which we observed in pubic symphysis fibrocartilage, but not in articular cartilage explants. The induction of these proteinases by relaxin or β-estradiol plus relaxin was accompanied by a loss of GAGs and collagen in joint fibrocartilage. None of the hormone treatments altered the synthesis of GAGs, suggesting that the loss of this matrix molecule probably resulted from increased matrix degradation. Indeed, fibrocartilaginous explants cultured in the presence of GM6001 showed an inhibition of relaxin-induced and β-estradiol plus relaxin-induced collagenase and stromelysin activities to control baseline levels that were accompanied by the maintenance of collagen or GAG content at control levels. These findings show for the first time that relaxin has degradative effects on non-reproductive synovial joint fibrocartilaginous tissue and provide evidence for a link between relaxin, MMPs, and matrix degradation.     

Acetylhomocysteine thiolactone protection against phosphamidon-induced alteration of regional superoxide dismutase activity in the central nervous system and its correlation with altered lipid peroxidation.

Phosphamidon intoxication (2 mg/kg body wt./day for 7 days) inhibited SOD activity, but enhanced the lipid peroxidation in various CNS regions. Administration of cithiolone (8 mg/kg body wt./day, ip for 7 days), however, elevated SOD activity and depleted lipid peroxidation. Interestingly, no significant change was observed either in SOD activity or in lipid peroxidation following simultaneous administration of phosphamidon and cithiolone.     

Morpho-physiological investigations in transgenic tomato (Solanum lycopersicum L.) over expressing OsRGLP1 gene

In Vitro Cellular & Developmental Biology - Plant - The OsRGLP1 gene was overexpressed under the control of CaMV 35S promoter in tomato (Solanum lycopersicum L.) plants using...     

Physiological rhythmicity in Malpura ewes to adapt to cold stress in a semi-arid tropical environment

A study was conducted to assess the rhythmic pattern of physiological parameter in Malpura ewes to adapt to cold stress in a semi-arid tropical environment. Eighteen adult Malpura ewes were selected for the present study. These ewes were randomly allocated into two groups: GI (Open shed; n=9) and GII (Protected; n=9). The study was conducted for a period of 30 days during the peak winter season (December 2011) during which the animals were stall fed. Blood samples were collected at fortnightly interval. The growth, physiological response, blood biochemical response and endocrine response parameters were studied. The results reveal that cold stress had significant negative influence on all the parameters studied in the ewes. In conclusion, it can be said that cold stress had significant influence on the biological functions in the ewes that would result in the impairment of their production and reproductive efficiency as well. The study also indicates the relevance of provision of appropriate protective measures to foster cold during the extreme winter months in the arid and semi-arid tropical areas.     

Biological ability of Malpura rams to counter heat stress challenges and its consequences on production performance in a semi-arid tropical environment

A study was conducted to assess the biological ability of Malpura rams to counter heat stress challenges and its impact on the productive performance in a semi-arid tropical environment. The eighteen adult Malpura rams (average body weight 55.0 kg) were divided into two groups, GI (n = 9; Control) and GII (n = 9; heat stress). The study was conducted for a period of 60 days. The results showed that body weight, body condition score, heart girth and feed intake were significantly (p < 0.05) lower in GII as compared to GI rams. The physiological responses i.e. respiration rate, pulse rate, rectal temperature and sweating rate (body and scrotum) were significantly (p < 0.05) higher in rams exposed to heat stress. Among the endocrine parameters, plasma T₃, T₄ and testosterone concentrations were significantly (p < 0.05) lower in GII rams, while cortisol concentration was significantly (p < 0.05) higher in GII rams. In addition, heat stress significantly (p < 0.05) reduced semen volume, total sperm motility, sperm concentration and progressive sperm motility in GII rams. The results indicated that Malpura rams adapted to the heat stress condition, however, while doing so their production performances were compromised.     

Role of external calcium in homeostasis of intracellular pH in the cyanobacterium Anabaena sp. strain PCC7120 exposed to low pH

The role of external Ca²⁺ in the homeostasis of intracellular pH (pHi) of Anabaena sp. strain PCC7120 in response to a decrease in the external pH (pHex) has been studied in cell suspensions. Increase in cytoplasmic pH after acid shock is dependent on the presence of Ca²⁺ in the medium. The observed Ca²⁺-mediated alkalization of the cytoplasm depends on the extent of the shift in external pH. Acid pH shifts resulted in an increased permeability of the cytoplasmic membrane to protons, which could be reversed by increasing the concentration of Ca²⁺ in the medium. Thus, the ability of Ca²⁺ to increase cytoplasmic pH might be correlated with an inhibition of net proton uptake by increasing concentrations of external Ca²⁺ under these conditions. This combined response resulted in the generation and maintenance of a larger pH gradient (ΔpH) at acid external pH values. All Ca²⁺ channel blockers tested, such as verapamil and LaCl₃, inhibited the observed Ca²⁺-mediated response. On the other hand, the Ca ionophore calcimycin (compound A23187) was agonistic, and stimulated both cytoplasmic alkalization and inhibition of net proton uptake. The protonophorous uncoupler carbonylcyanide m -chlorophenyl hydrazone, inhibited this Ca²⁺-mediated response, whereas monensin, an inhibitor of the Na⁺/H⁺ antiporter, had no significant effect. The results of the present study suggest that an influx of Ca²⁺ from the extracellular space is required for the regulation of cytoplasmic pH in Anabaena sp. strain PCC7120 exposed to low external pH values.