Aloe vera (蘆薈 lú huì) is well known for its considerable medicinal properties. This plant is one of the richest natural sources of health for human beings coming. The chemistry of the plant has revealed the presence of more than 200 different biologically active substances. Many biological properties associated with Aloe species are contributed by inner gel of the leaves. Most research has been centralized on the biological activities of the various species of Aloe, which include antibacterial and antimicrobial activities of the nonvolatile constituents of the leaf gel. Aloe species are widely distributed in the African and the eastern European continents, and are spread almost throughout the world. The genus Aloe has more than 400 species but few, such as A. vera, Aloe ferox, and Aloe arborescens, are globally used for trade. A. vera has various medicinal properties such as antitumor, antiarthritic, antirheumatoid, anticancer, and antidiabetic properties. In addition, A. vera has also been promoted for constipation, gastrointestinal disorders, and for immune system deficiencies. However, not much convincing information is available on properties of the gel. The present review focuses on the detailed composition of Aloe gel, its various phytocomponents having various biological properties that help to improve health and prevent disease conditions.

BackgroundGnRH is the master molecule of reproduction that is influenced by several intrinsic and extrinsic factors such as neurotransmitters and neuropeptides. Any alteration in these regulatory loops may result in reproductive-endocrine dysfunction such as the polycystic ovarian syndrome (PCOS). Although low dopaminergic tone has been associated with PCOS, the role of neurotransmitters in PCOS remains unknown. The present study was therefore aimed at understanding the status of GnRH regulatory neurotransmitters to decipher the neuroendocrine pathology in PCOS.MethodsPCOS was induced in rats by oral administration of letrozole (aromatase inhibitor). Following PCOS validation, animals were assessed for gonadotropin levels and their mRNA expression. Neurotrasnmitter status was evaluated by estimating their levels, their metabolism and their receptor expression in hypothalamus, pituitary, hippocampus and frontal cortex of PCOS rat model.ResultsWe demonstrate that GnRH and LH inhibitory neurotransmitters – serotonin, dopamine, GABA and acetylcholine – are reduced while glutamate, a major stimulator of GnRH and LH release, is increased in the PCOS condition. Concomitant changes were observed for neurotransmitter metabolising enzymes and their receptors as well.ConclusionOur results reveal that increased GnRH and LH pulsatility in PCOS condition likely result from the cumulative effect of altered GnRH stimulatory and inhibitory neurotransmitters in hypothalamic-pituitary centre. This, we hypothesise, is responsible for the depression and anxiety-like mood disorders commonly seen in PCOS women.

The mechanism of testicular toxicity of lead (Pb) and cadmium (Cd) is poorly understood. Previous studies focused on single metal-related changes in testicular toxicity. This study points towards the possible involvement of Pb- and Cd-induced oxidative stress in the suppression of steroidogenesis. The oxidative status of testis of adult male rats exposed to Pb acetate and cadmium acetate either alone or in combination at a dose of 0.025 mg kg(-1) body weight of metal intraperitoneally for 15 days was studied. Pb and Cd caused an increase in reactive oxygen species (ROS) by elevating testicular malondialdehydes (MDA) and decrease in activities of testicular antioxidant enzymes superoxide dismutase (SOD), catalase, glucose 6 phosphate dehydrogenase (G6PDH) and glutathione-S-transferase (GST) in mitochondrial and/or post-mitochondrial fraction. Activities of steroidogenic enzymes 3β and 17β-hydroxysteroid dehydrogenase also decreased significantly leading to altered testosterone production. Metal-exposed groups showed significantly decreased testicular and epididymal sperm count. Epididymal sperm motility and viability was also decreased on Pb and Cd exposure. Cd exposure showed more toxic effect than lead exposure, while combined exposure demonstrated least toxicity. In vitro experiments showed that vitamin C restores steroidogenic enzyme activities, suggesting that Pb- and Cd-induced ROS inhibits the testicular steroidogenesis.

The effects of combined exposure to lead and cadmium on granulose cells were studied. Adult female rats were treated i.p. with either lead acetate (LA) or cadmium acetate (CA) both, alone, or in combination at a dose of 0.05 mg/kg body weight on a daily basis for 15 days. Both metals were accumulated in the ovary after metal exposure. Metal exposure caused a decrease in reduced glutathione content along with elevated lipid peroxidation in all groups. Granulose cells of both cadmium as well as combination group demonstrated a maximum increase in lipid peroxides and catalase activity, along with decreased glutathione status and superoxide dismutase activities. Combined treated animals exhibited an intermediate effect in antioxidant status. However, "in vitro" exposure showed no significant change in antioxidant enzymes in all metal exposed cells. Data from the present study indicates that lead and cadmium in isolation and in combination cause oxidative stress. Lead and cadmium in combination do not show additive or synergistic effect indicating the competition between them due to similarity in electronic affinities. Present study highlights the effects of toxic metals that disturb membrane integrity of cells via ROS and thereby classifying mechanism for altered receptor binding, steroidogenesis, and hormone production.

This is a preliminary study that explores the efficacy of Aloe vera gel formulation as a possible therapeutic agent in the prevention and management of polycystic ovary syndrome (PCOS). PCOS is recognized as the most common endocrinopathy of women. Increased androgen synthesis, disrupted folliculogenesis, and insulin resistance lie at the patho-physiological core of PCOS. Current therapy for such a syndrome is use of insulin sensitizers. Large randomized clinical trials of metformin as the insulin-sensitizing drug, however, suggested that it produces many side effects after prolonged usage. For this reason, an alternate therapy would be to use herbs with hypoglycemic potential. Aloe barbadensis Mill. (Liliaceae) popularly known as Aloe vera is a well-known plant with such properties. The present study evaluated the efficacy of Aloe vera gel formulation in a PCOS rat model. Five month old Charles Foster female rats were orally fed with letrozole, a non-steroidal aromatase inhibitor, to induce PCOS. The rats were then treated orally with the Aloe vera gel formulation (1 ml dose daily for 45 days). This restored their estrus cyclicity, glucose sensitivity, and steroidogenic activity. Co-treatment of the inductive agent (letrozole) with the Aloe vera gel prevented the development of the PCO phenotype. Aloe vera gel formulation exerts a protective effect in against the PCOS phenotype by restoring the ovarian steroid status, and altering key steroidogenic activity. This can be attributed to phyto-components present in the extract.

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Adult virgin 4-day cycling synchronized Charles foster females were treated subcutaneously (0.05 mg/kg body wt/day) with sodium acetate (control), lead acetate or cadmium acetate alone, or both during gestational period, with pretreatment of 5 days prior to mating. There were no alterations in reproductive performance in all metal-treated groups. Implantation enzymes, cathepsin-D and alkaline phosphatase, activity were altered, but no change in the reproductive performance was observed. The key steroidogenic enzymes of ovary and placenta (3beta-HSD and 17beta-HSD), along with gonadal steroids, were affected the most in cadmium and combined treated animals whereas lead-treated animals showed a minimum change compared to the control group. Maximum displacement of zinc bound to metallothionein was more in cadmium and combined treated rats when compared to other metal-treated groups. Biomolecules such as glycogen, protein, RNA, DNA, and protein content were affected in all metal-treated groups, whereas cadmium-treated animals showed greater effect. General parameters of toxicity such as alkaline phosphatase, serum glutamate pyruvate transaminase, and creatinine were altered but were within the normal range. Biochemical effects are correlated with metals accumulated in blood, reproductive tissue such as placenta and ovary.

Neurotransmitter alteration could be one of the reasons for disturbed gonadotropin-releasing hormone (GnRH) release, consequently directing the ovarian dysfunction in PCOS. Also, decrease in neurotransmitters, mainly NE, serotonin and dopamine (DA) attributes to mood disorders like depression and anxiety in PCOS.