Hormone-sensitive lipase (HSL) is known to mediate the hydrolysis not only of triacylglycerol stored in adipose tissue but also of cholesterol esters in the adrenals, ovaries, testes, and macrophages. To elucidate its precise role in the development of obesity and steroidogenesis, we generated HSL knockout mice by homologous recombination in embryonic stem cells. Mice homozygous for the mutant HSL allele (HSL؊͞؊) were superficially normal except that the males were sterile because of oligospermia. HSL؊͞؊ mice did not have hypogonadism or adrenal insufficiency. Instead, the testes completely lacked neutral cholesterol ester hydrolase (NCEH) activities and contained increased amounts of cholesterol ester. Many epithelial cells in the seminiferous tubules were vacuolated. NCEH activities were completely absent from both brown adipose tissue (BAT) and white adipose tissue (WAT) in HSL؊͞؊ mice. Consistently, adipocytes were significantly enlarged in the BAT (5-fold) and, to a lesser extent in the WAT (2-fold), supporting the concept that the hydrolysis of triacylglycerol was, at least in part, impaired in HSL؊͞؊ mice. The BAT mass was increased by 1.65-fold, but the WAT mass remained unchanged. Discrepancy of the size differences between cell and tissue suggests the heterogeneity of adipocytes. Despite these morphological changes, HSL؊͞؊ mice were neither obese nor cold sensitive. Furthermore, WAT from HSL؊͞؊ mice retained 40% of triacylglycerol lipase activities compared with the wild-type WAT. In conclusion, HSL is required for spermatogenesis but is not the only enzyme that mediates the hydrolysis of triacylglycerol stored in adipocytes.

and methamphetamine-induced locomotor stimulation and stereotyped behaviors in rats [S-7]. Despite these significant functional roles in the central nervous system, the presence of free D-amino acids in mammalian brain has not yet btien demonstrated, with the exception of the small amounts of free neutral amino acids in mice and human brains [8,9] and of free D-aspartate in adult rat and human brains (less than 3% of total aspartate) [l&12]. In the present study, we report the identification and the concentration of the free D-enantiomer of serine in adult rat brain using gas chromatographic (GC) analy- MATERIALS AND METHODSAll amino acids and trichloroacctic acid (TCA) were oblainrd rrom Nakardi Tcsquc (Japan). All solvcnls were HPLC grade and purchased from Kanto Chemicals (Japan). A pcntafluoropropionic anhydride (PFPA) was purchased from G.L.C. Scicncc (Japun). The column head pressure was I IO kPa. and the helium flow-mu on the column was 0.4 ml/min; the flow-rate (plus auxiliary gas) was 30 mllmin. The hydrogen flow-ralc and the air flow-rate al the dctcctor were 3.5 and I IO ml/min, rcspcctivcly. Peak arca was dclcrmined using a SIC chromalocorder I I intcgralor (Syslcm Inslrumcnu Co.). rWS umi/~v.si,sThe GC-MS analysis was pcrrormcd on a V.G. Masslab Trio-l mass spectrometer (Jasco, ImcrnaGonal Co., Japan), equipped with a Hcwlcu Packard 5890A gas chromalograph. The GC condilions wcrc the Same as for the GC analysis with the cxcplion oi a spiititisj. injection. The mass spcctromctcr con&ions wcrc: clcc~ron accclcraling voliugc, 70 cV; inicrracc tcmpcr?lurc, 170°C; photomul1iplicr 33

Recently, a substantial amount of free D-serine has been demonstrated in rat brain, although it has long been presumed that D-amino acids are uncommon in mammals. The anatomical distribution and age-related changes in endogenous D-serine have been examined here to obtain insight into its physiological functions. Free D-serine exclusively occurs in brains, with a persistent high content from birth to at least 86 postnatal weeks. The patterns of the regional variations and the postnatal changes in brain D-serine are closely correlated with those of the N-methyl-D-aspartate (NMDA)-type excitatory amino acid receptor. Because D-serine potentiates NMDA receptor-mediated transmission by selective stimulation of the strychnine-insensitive glycine site of the NMDA receptor, it is proposed that D-serine is a novel candidate as an intrinsic ligand for the glycine site in mammalian brain.