Search

This is the second feature appearing in our “On the Lighter Side of Science” column. Dr. Joanne Morse is the highlighted writer once again and will talk about different aspects of science from a no...

The mediation of lesion-induced sprouting in the nervous system is a complex interaction of local membrane factors and circulating hormones. This series of studies examines the reactivity of the sprouting response of both male and female subjects under different hormonal conditions. Young adult male and female Sprague-Dawley rats which were gonadectomized (GDX) and adrenalectomized (ADX) underwent a unilateral entorhinal cortex lesion, which partially denervates the molecular layer of the ipsilateral hippocampal dentate gyrus. At the time of the lesion, each animal received hormonal therapy. Fifteen days post-ERC-ab-lation the brains were analyzed for changes in reactive fiber outgrowth in the hippocampal commissural/associational afferents. Fiber outgrowth in females in the “asteroidal” ( GDX ADX ) condition was unaffected. Asteroidal males demonstrated a decreased response. Gonadal steroid replacement, estrogen or testosterone, enhanced outgrowth in both asteroidal males and females. Glucocorticoid replacement suppressed outgrowth in both asteroidal males and females. Gonadal steroids clearly have neurotrophic activity which is interactive with glucocorticoid activity. Glucocorticoids under the GDX ADX conditions in vivo have a negative impact on fiber outgrowth in both sexes. The effect of glucocorticoids is most dramatic when compared to the outgrowth of asteroidal animals without additional hormonal supplementation.

Cranberry has been used for centuries as a source of food and for medicinal purposes. This herbal fruit would not have been mentioned in the Bible as it was not found in arid climates. It has been found in the northern regions of North America, Europe, and Asia, and goes by many names such as craneberry, and Sassamanash. Native Americans used the berry for indigestion, kidney disease, lung ailments, and in poultice form for cuts and abrasions. Europeans also used it for digestive problems, gall bladder attacks, blood disorders, and kidney stones, while New England settlers used it as a way to prevent scurvy at sea. Cranberries were used by sea farers much like the British sailors used limes to prevent scurvy. It was the high vitamin “C” content in the cranberries which was otherwise lacking in a sailors diet. Nutritionally cranberries contain several vitamins and minerals. They contain vitamin E (alpha tocopherol) and vitamin K, as well as being a good source of fiber, vitamin C and manganese.

Milk Thistle (MT) ranks 5th or 6th, according to the venue surveyed, in the top 20 herbs sold in the US in 2011. MT has also been assigned a grade of “B” from the Natural Standard Database staff scientists. These two ratings in combination give the impression that MT is one of those herbs that it would be important to understand from both an historical and a safety standpoint. This short monograph discusses MT from an historical perspective as well as laying out the myriad of safety concerns that accompany all botanicals used as alternative medicines.

Research into the efficacy of herbs for glucose control in patients with diabetes is still lacking. Although numerous scientific studies have been performed on laboratory animals with positive results, the studies on humans remains in its infancy and often show inconsistent outcomes. Therefore, a review of the current published literature on the efficacy in humans of four popular herbs to “treat” diabetes: Gymnema sylvestre, fenugreek, bitter melon, and cinnamon, was deemed appropriate (see table 6 for images). Current evidence weakly supports the use of these specific herbs in the treatment of diabetes. The Natural Standard Database grades herbs based on the significant findings from well designed scientific clinical trials, with additional support from animal studies. Results, were for the most part, inconsistent, mostly due to the use of unstandardized methodologies and the small numbers in the sample populations. Further studies are needed to gauge the efficacy of each herb on a much larger population before one can support their use with complete confidence.

When the circulation to the brain is briefly interrupted and then restored, only certain neurons are damaged. This selective neuronal vulnerability after transient ischemia is found in many brain regions, but is perhaps most dramatic in the hippocampus. There, both CA1 and CA4 neurons are damaged, but CA1 neurons die only after a definite delay. This delay has been the focus of intense research in the past decade with the hope that a better understanding of this type of damage will lead to effective therapies which can be administered to patients after periods of transient ischemia.

Adrenalectomy protects hippocampal pyramidal cells from transient ischemia in rats. We hypothesized that this effect of adrenalectomy could be generalized to the gerbil. We determined the effect of glucocorticoid manipulation on hippocampal CA1 cell death following transient forebrain ischemia in the gerbil. Adrenalectomy diminished hippocampal damage when performed immediately following transient forebrain ischemia, as in the rat, while glucocorticoid administration resulted in an increase in CA1 pyramidal cell damage. Furthermore adrenalectomy 24 h after the ischemic injury diminished hippocampal damage to roughly the same extent as immediate adrenalectomy. However, if gerbils were examined at longer survival periods after ischemia, the difference in hippocampal damage between adrenalectomized and sham-adrenalectomized was lost. These findings suggest that glucocorticoids influence the rate of hippocampal pyramidal cell disappearance following ischemia. Manipulation of glucocorticoids could be an important adjunct to therapy for preventing ischemic brain damage.

Young adult Sprague-Dawley rats of either sex were randomly assigned to be gonadectomized or left intact. Capsules containing either testosterone or estrogen were implanted in animals in both categories. Fifteen days after removal of the entorhinal cortex, the brains were analyzed for changes in reactive outgrowth of the commissural-associational afferent fibers in the hippocampal dentate gyrus. Both male and female control subjects showed identical sprouting responses. Only female subjects were significantly affected by gonadectomy, resulting in significant decreases in reactive fiber outgrowth. Hormone replacement therapy resulted in a return to control values in castrated females but had no affect on castrated males. The results suggest that sex hormones may regulate axon sprouting in the mature central nervous system.

Young adult male and female Sprague-Dawley rats were randomly assigned to be gonadectomized (GDX), adrenalectomized (ADX), gonadectomized and adrenalectomized (GDX/ADX) or left intact. One week following initial surgery all animals were subjected to a lesion of the entorhinal cortex (ERC) which partially denervates the ipsilateral hippocampal dentate gyrus. Fifteen days after the ERC ablation, the brains were analyzed for changes in reactive outgrowth of the hippocampal commissural-associational (C-A) afferents. Under intact conditions there were no differences between male and female subjects. Female subjects demonstrated a suppression of sprouting following GDX alone and an enhancement of growth following ADX alone. Reactive growth in male subjects was unaffected by GDX or ADX alone. When placed in the ‘asteroidal’ (GDX/ADX) condition, reactive outgrowth of male subjects in significantly impaired as compared to female subjects. The results suggest a complex inter-relationship between the gonadal and adrenal hormones and a possible neurotrophic effect for the gonadal steroids.

Hydrocortisone was administered to young adult male or female rats after removal of the entorhinal cortex. Lesion-induced outgrowth of the commissural-associational afferent fibers in the hippocampus was quantitated. The glucocorticoids caused a significant decline in axon sprouting in the male subjects and a significant increase in outgrowth in female subjects. Depending on the sex, the hormonal effects on lesion-induced axonal growth are markedly different in the rat.