Three brain regions, including the hypothalamus, thalamus, and periaqueductal gray-rostral pons, were dissected and extracted with 0.1n HCL. at 4 hour intervals during the 24 hour period. The animals were sacrificed by microwave for 4.25 sec. Male Sprague-Dawley rats were maintained for three weeks under controlled light (12L:12D) and temperature (23 Р’В± 1 РІВРЉ). The data obtained correlated the diurnal variations in beta-endorphins, serotonin and pain response.Р”Р„bstract = 'A circadian rhythm for beta-endorphin content in several regions of the rat brain has been established. In another study, the relationship between the circadian rhythm of beta-endorphin and 5-HT was established. These results are in agreement with previous studies which have demonstrated diurnal changes in responsivity to painful stimuli and morphine induced analgesia. The level of beta-endorphin in the periaqueductal gray-rostral pons region significantly decreased during the light phase and increased during the dark phase. In the thalamus, there was no significant change in the levels of beta-endorphin. These data show significant circadian variations in beta-endorphin content in the hypothalamus. In the hypothalamus, beta-endorphin levels increased during the dark phase with a peak concentration occurring at 0400 hour. Phase separation was accomplished by the addition of goat anti-rabbit serum in the presence of carrier rabbit serum which is titered to assure mid-zone precipitation. This method employed addition of delayed tracer to improve sensitivity. Beta endorphin content was measured by radioimmunoassay. However, in recent years, there has been a lively debate about the validity of assigning and using a beta value as an accurate predictor of stock performance.A circadian rhythm for beta-endorphin content in several regions of the rat brain has been established. Betas as low as 0.5 and as high as 4 are fairly common, depending on the sector and size of the company. But a stock with a beta lower than 1 would be expected to be more stable in price and move less. Under the same market conditions, however, a stock with a beta of 1.5 would move 3% (2% increase x 1.5 beta = 0.03, or 3%). That means if the S&P 500 moves 2% in either direction, a stock with a beta of 1 would also move 2%. The higher the beta, the more sharply the value of the investment can be expected to fluctuate in relation to a market index.Р”Р‡or example, Standard & Poor's 500 Index (S&P 500) has a beta coefficient (or base) of 1.

Beta.Р”В«eta is a measure of an investment's relative volatility. Copyright Р’В© 2003 by Houghton Mifflin Company. Wall Street Words: An A to Z Guide to Investment Terms for Today's Investor by David L. It is possible for a security to have a zero beta and higher volatility than the market. Also, note that the beta is a measure of co-movement, not volatility. betas may be greater for down moves in the market rather than up moves) (3) the estimated beta will be biased if the security does not frequently trade (4) the beta is not necessarily a complete measure of risk (you may need multiple betas). When using beta, there are a number of issues that you need to be aware of: (1) betas may change through time (2) betas may be different depending on the direction of the market (i.e. According to asset pricing theory, beta represents the type of risk, systematic risk, that cannot be diversified away. Roughly speaking, a security with a beta of 1.5, will have move, on average, 1.5 times the market return. The measure of an asset's risk in relation to the market (for example, the S&P500) or to an alternative benchmark or factors.