Circadian Hormone Rhythms in Lipid Regulation

Bromocriptine Alters Hormone Rhythms and Lipid Metabolism in Swine

“…5). Several studies [6][7][8] in cluding recent studies of hamster hepatocyte cultures indicate that prolactin levels must be low as well as high at the proper times of day to stimulate lipogenesis. In hamster he patocyte cultures, addition of prolactin to the culture 16-20 h before the daily interval of lipogenic response to insulin greatly in creased the response [29], probably in part by increasing the insulin receptor number [11], However, the addition of prolactin to the culture medium 28 h before the lipogenic response interval to insulin blocks the stimu latory influence prolactin has when present 20 h beforehand and actually inhibits lipo genesis.…”

“…Such distinct differences in the relationships of the corticosteroid and prolactin variations during a day have been observed in lean and fat animals of several species among all the major vertebrate classes [3][4][5]. Furthermore, timed daily injections of both corticosteroid and prolactin can induce fattening or loss of body fat as a function of the time relation ship of injections [8,30,31 ]. It was suggested that lipid metabolism is regulated by two cir cadian neuroendocrine rhythms of which the cortisol and prolactin rhythms are individ ual expressions and that cortisol and prolac tin injections can reset the phases of the two circadian oscillations, thus resetting the phase relationships of all the circadian neu ral and hormonal expressions of the two cir cadian systems.…”

“…Early research in nonmammalian verte brates demonstrated central roles for prolac tin and circadian rhythms in the regulation of lipogenesis and body fat stores [1,2], It was found that the phases of the prolactin rhythms differed in lean and fat animals with respect to time of day and to the phases of rhythms of other hormones such as plasma corticosteroid [3][4][5], Furthermore, daily injections of prolactin at times of day when the daily peak of the endogenous hor mone was known to occur in fat animals caused increases in body fat stores in lean animals whereas prolactin injections at times when prolactin peaks occurred in lean animals caused losses of fat stores in fat ani mals [6][7][8], Daily variations in the fattening responses to prolactin injections have now been demonstrated in more than 25 species including representatives of all the major vertebrate classes [9,10].…”

Prolactin and Bromocryptine Induced Changes in Liver, Adipose Tissue and Blood Lipids of Mature Male Bonnet Monkeys, Macaca radiata (Geoffroy).

“…The physiological changes in reproductive and other endocrine organ in hyperprolactinaemia have been reviewed extensively [5][6]. Although prolactin is known to influence lipid metabolism in a number of vertebrates [7][8][9][10], the impact of hyperprolactinaemia on lipid metabolism, particularly in higher primates is not well understood.…”

Revue bibliographique : Variations quantitatives et métabolisme des lipides dans les tissus adipeux et le foie au cours du cycle gestation-lactation. 1re partie : chez la ratte

“…Les catécholamines pourraient participer à cette résistance à l'insuline (Loennroth, 1984 (Joseph et Meier, 1974 ;Meier et Burns, 1976). Par ailleurs, les glucocorticoïdes stimulent (De Gasquet et al, 1975) ou inhibent (Kerpel et Laudat, 1967 ;Krausz et al, 1981) l'activité LPL du tissu adipeux de rat in vivo, et potentialisent l'effet stimulant de l'insuline in vitro (Ashby et Robinson, 1980).…”