Mg2+-dependent and Ca2+, Mg2+-dependent ATPase activities in the Harderian gland of rodents: Age and sex influences
Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio 78284, USA.Microscopy Research and Technique (Impact Factor: 1.15). 07/1996; 34(2):144-8.
Three experiments employing male and female Syrian hamsters (aged 1, 2, and 8-10 months), male Sprague-Dawley rats (aged 1, 2, and 10 months) and male C57B1 mice (aged 2, 7, 13, and 29 months) examined the effects of age and sex on Mg(2+)-dependent and Ca2+, Mg(2+)-dependent ATPase activity in the Harderian gland. Significant differences due to age and sex were observed in the hamsters and rats but not with age in mice. Generally, male hamsters had significantly higher Mg(2+)-dependent and Ca2+, Mg(2+)-dependent (exception at one timepoint) ATPase activity than did females. Age-matched male and female rats had similar values of Mg(2+)-dependent ATPase activity, but males had significantly higher Ca2+, Mg(2+)-dependent ATPase activity than females at 2 months of age.
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ABSTRACT: Lead poisoning induces hematological, gastrointestinal and neurological dysfunctions. One of the potential mechanisms is the inhibition of calcium-pump (Ca-pump), a transport protein. We investigated the effects of an environmental low lead exposure on Ca-pump activity in 247 mothers and their newborns. Maternal and cord blood, and newborn and mother hair, were sampled at delivery. Geometric means for mother and cord blood lead (Pb-B), and for mother and newborn hair lead (Pb-H), were 6.3 and 4.8 microg/dl, and 1.7 and 1.1 microg/g. Means for mother and cord basal Ca-pump activities were 2,442 and 2,675 nM/mg/hr. Mother enzymatic activity was negatively related to her Pb-B and Pb-H and to the cord Pb-B and newborn Pb-H levels. Newborn enzymatic activity was negatively related to his Pb-H level only. Adjustment for gestational age, child's sex, mother's age at delivery, alcohol, coffee and tea consumption, and smoking habits during pregnancy did not modify these relationships. Our findings support the hypothesis that lead toxicity could be in part mediated by a reduction of Ca-pump activity. This effect could be observed at low environmental exposure, in mothers and newborns.
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ABSTRACT: The aim of the present work was to study the sexual differences in secretory mechanisms and intracellular calcium ion dynamics in the Harderian gland of the golden hamster. In both sexes the Harderian gland consisted of small and large lobes. In the intact control male glands the secretory portions of both lobes showed wide lumina that contained secretory material and cytoplasmic fragments, suggestive of the occurrence of exocytosis and apocrine secretion. After perfusion with HEPES-buffered Ringer's solution containing 10 microM carbamylcholine (CCh), the glandular cells showed features of enhanced secretion and a rise in intracellular calcium concentration ([Ca2+]i). In the intact control female gland the lumina of most secretory portions in the large lobe contained porphyrin accretions, and exocytosis was the sole secretory mechanism. Stimulation of the large lobe with 10 microM CCh did not raise [Ca2+]i or cause enhanced secretion. The small lobe in females resembled the male gland in secretory functions, and CCh administration caused enhanced secretion and a rise in [Ca2+]i. Castration in males abolished apocrine secretion; exocytosis became the sole secretory mechanism, and stimulation of the glandular cells with CCh did not cause enhanced secretion or induce a rise in [Ca2+]i. To the contrary, in females, castration restored apocrine secretion and CCh administration caused enhanced secretion and a rise in [Ca2+]i. Castration did not affect the secretory mechanisms and the effect of CCh on the glandular cells in the small lobes of both male and female glands. The present study points to the possibility that sex hormones may control the functioning or expression of muscarinic receptors in the Harderian gland of the golden hamster.
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