To study the physiological and molecular mechanisms of age-related memory loss, we assessed spatial memory in C57BL/B6 mice from different age cohorts and then measured in vitro the late phase of hippocampal long-term potentiation (L-LTP). Most young mice acquired the spatial task, whereas only a minority of aged mice did. Aged mice not only made significantly more errors but also exhibited greater individual differences. Slices from the hippocampus of aged mice exhibited significantly reduced L-LTP, and this was significantly and negatively correlated with errors in memory. Because L-LTP depends on cAMP activation, we examined whether drugs that enhanced cAMP would attenuate the L-LTP and memory defects. Both dopamine D1/D5 receptor agonists, which are positively coupled to adenylyl cyclase, and a cAMP phosphodiesterase inhibitor ameliorated the physiological as well as the memory defects, consistent with the idea that a cAMP–protein kinase A-dependent signaling pathway is defective in age-related spatial memory loss.

https://www.pnas.org/content/pnas/96/9/5280.full.pdf

Age-related defects in spatial memory are correlated with defects in the late phase of hippocampal long-term potentiation in vitro and are attenuated by drugs that enhance the cAMP signaling pathway.

Mammalian reproduction poses an immunological paradox because fetal alloantigens encoded by genes inherited from the father should provoke responses by maternal T cells leading to fetal loss. Current understanding of T cell immunobiology and the critical role of inflammatory processes during pregnancy is reviewed and discussed. Lessons derived from studies on the regulation of T cell responsiveness during mammalian gestation are considered in the wider context of T cell tolerance toward some microbial infections and tumors, avoidance of autoim- munity, and tissue allograft rejection.

INTERFACE: Lessons for T Cell Tolerance and Suppression

Mammalian reproduction poses an immunological paradox because fetal alloantigens encoded by genes inherited from the father should provoke responses by maternal T cells leading to fetal loss. Current understanding of T cell immunobiology and the critical role of inflammatory processes during pregnancy is reviewed and discussed. Lessons derived from studies on the regulation of T cell responsiveness during mammalian gestation are considered in the wider context of T cell tolerance toward some microbial infections and tumors, avoidance of autoimmunity, and tissue allograft rejection.

Immunology at the Maternal-Fetal Interface: Lessons for T Cell Tolerance and Suppression

The present invention provides methods and compositions for modification and regulation of glucose and lipid metabolism, generally to reduce insulin resistance, hyperglycemia, hyperinsulinemia, obesity, hyperlipidemia, hyperlipoprotein-emia (such as chylomicrons, VLDL and LDL), and to regulate body fat and more generally lipid stores, and, more generally, for the improvement of metabolism disorders, especially those associated with diabetes, obesity and/or atherosclerosis.

Method of regulating glucose metabolism, and reagents related thereto

It appears advantageous for many non-human animals to store energy body fat extensively and efficiently because their food supply is more labile and less abundant than in their human counterparts. The level of adiposity in many of these species often shows predictable increases and decreases with changes in the season. These cyclic changes in seasonal adiposity in some species are triggered by changes in the photoperiod that are faithfully transduced into a biochemical signal through the nightly secretion of melatonin (MEL) via the pineal gland. Here, we focus primarily on the findings from the most commonly studied species showing seasonal changes in adiposity-Siberian and Syrian hamsters. The data to date are not compelling for a direct effect of MEL on white adipose tissue (WAT) and brown adipose tissue (BAT) despite some recent data to the contrary. Thus far, none of the possible hormonal intermediaries for the effects of MEL on seasonal adiposity appear likely as a mechanism by which MEL affects the photoperiodic control of body fat levels indirectly. We also provide evidence pointing toward the sympathetic nervous system as a likely mediator of the effects of MEL on short day-induced body fat decreases in Siberian hamsters through increases in sympathetic drive on WAT and BAT. We speculate that decreases in the SNS drive to these tissues may underlie the photoperiod-induced seasonal increases in body fat of species such as Syrian hamsters. Clearly, we need to deepen our understanding of seasonal adiposity, although, to our knowledge, this is the only form of environmentally induced changes in body fat where the key elements of its external trigger have been identified and can be traced to and through their transduction into a physiological stimulus that ultimately affects identified responses of white adipocyte physiology and cellularity. Finally, the comparative physiological approach to the study of seasonal adiposity seems likely to continue to yield significant insights into the mechanisms underlying this phenomenon and for understanding obesity and its reversal in general.

Seasonal changes in adiposity: the roles of the photoperiod, melatonin and other hormones, and sympathetic nervous system.

Daily injections of dihydroxyphenylalanine (DOPA), a precursor for dopamine synthesis, given 12 hr after daily injections of 5-hydroxytryptophan (5-HTP), a serotonin precursor, induced uterine growth and increased serum thyroxine and luteinizing hormone (LH) concentrations in scotosensitive female hamsters maintained on short daylengths. On the other hand, daily injections of DOPA given at the same time as daily injections of 5-HTP reduced uterine weights and serum concentrations of thyroxine and LH in scotorefractory female hamsters. These results indicate that the endogenous mechanism controlling seasonality (scotosensitivity and scotorefractoriness) in the Syrian hamster may be reset by drugs that influence serotonergic and catecholaminergic activity. This seasonal mechanism might involve two circadian systems that undergo seasonal changes in their phase relations.

Resetting the annual cycle with timed daily injections of 5-hydroxytryptophan and L-dihydroxyphenylalanine in Syrian hamsters.

This invention relates to a method for modifying metabolism in a vertebrate animal which entails the administration of pantethine or cysteamine at a predetermined time daily. The method is useful in the treatment of hyperglycemia, glucose intolerance, insulin resistance, and hyperinsulinemia.

Method for regulating glucose metabolism

Naturally obese female Syrian hamsters were injected daily with prolactin at 0 or 12 h after cortisol injections for 10 days while held in constant light. Controls were similarly injected with saline. Animals were then held on short daylengths (10 h light:14 h darkness) for 10 weeks. They were allowed free access to food and water from birth to time of death. Ten weeks after treatment, retroperitoneal fat stores, plasma concentrations of insulin and glucose, and hypoglycaemic responsiveness to exogenous insulin were determined. The control groups as well as the 12-h hormone treatment group were obese, hyperinsulinaemic and insulin resistant. However, the 0-h treatment dramatically reduced retroperitoneal fat stores (41-55%), plasma insulin concentration (60-70%) and the insulin to glucose ratio (63-68%) compared with controls. Values for these parameters in the 0-h treatment groups were similar to those of their lean litter-mates. Furthermore, the 0-h group but not the 12-h group was more sensitive than control animals to the hypoglycaemic effects of exogenous insulin at doses 0.2 and 2.0 U/kg body weight. These results demonstrate that timed daily injections of cortisol and prolactin in specific temporal relationships can produce marked reductions in obesity, hyperinsulinaemia and insulin resistance in the Syrian hamster that persist long after the termination of treatment. This study also suggests an important role for the interactions of circadian neuroendocrine systems in the regulation of these metabolic states.

Properly timed injections of cortisol and prolactin produce long-term reductions in obesity, hyperinsulinaemia and insulin resistance in the Syrian hamster (Mesocricetus auratus)

Disclosed are methods for improving various aberrant metabolic indices in mammals including humans by administration of muscarinic (particularly M1) receptor antagonists alone or in combination with prolactin inhibiting compounds. Preferably the administration takes place at a predetermined time (or, if a combination of muscarinic receptor antagonist and prolactin inhibitor is used, at different predetermined times) during a 24-hour period when the administration is effective (or its effect more pronounced). The invention has application in the treatment of lipid and glucose metabolism disorders.

Administration of pirenzepine, methyl scopolamine and other muscarinic receptor antagonists for treatment of lipid metabolism disorders

Disclosed herein are methods for regulating or ameliorating lipid and glucose metabolism and reducing in a vertebrate animal body fat stores, insulin resistance, hyperinsulinemia, hyperglycemia, hyperlipidemia, elevated blood lipoproteins (such as triglycerides and cholesterol including chylomicrons, VLDL and LDL) and/or increasing in the subject the plasma HDL. The methods comprise administration or timed administration of inhibitors or dopamine beta hydroxylase (DBH).

John M. Wilson

Papers

Resetting the annual cycle with timed daily injections of 5-hydroxytryptophan and L-dihydroxyphenylalanine in Syrian hamsters.

Method for regulating glucose metabolism

Properly timed injections of cortisol and prolactin produce long-term reductions in obesity, hyperinsulinaemia and insulin resistance in the Syrian hamster (Mesocricetus auratus)

Administration of pirenzepine, methyl scopolamine and other muscarinic receptor antagonists for treatment of lipid metabolism disorders

Method for regulating metabolism with dopamine beta hydroxylase inhibitors