The sympathetic nervous system plays a major role in energy expenditure. By catecholamine stimulation, lipolysis in white adipose tissue and thermogenesis in brown adipose tissue and skeletal muscle are induced. These effects are mediated by several subtypes of catecholamine receptors namely Summary The Trp64Arg mutation of the b 3-adrenergic receptor (b3AR) is prevalent in several ethnic groups and is associated with weight gain, and some features of syndrome X such as insulin resistance and dyslipidaemia. Nevertheless, it is not known at present whether this mutation is associated with visceral obesity, which is an important risk factor for the development of hypertension, dyslipidaemia, insulin resistance, non-insulin-dependent diabetes mellitus, and atherosclerosis. To investigate whether this mutation may contribute to visceral obesity, we studied the relationships between b 3AR genotypes and clinical phenotypes. The Trp64Arg allele of b 3AR was examined in 278 Japanese men with respect to variables relating to visceral obesity assessed by computerised tomography. To detect the Trp64Arg mutation, polymerase chain reaction-restriction fragment length polymorphism analysis using Bst NI digestion was performed. This mutation was more frequently observed in subjects with higher body mass index (BMI) (p = 0.02). Moreover, in 120 subjects with a moderate degree of obesity (222 ), the mutation (homozygotes and heterozygotes) was associated with visceral obesity (higher ratio of visceral to subcutaneous fat area; V/S) (p = 0.03). Furthermore, the Trp64Arg allele was more frequent in subjects with lower serum triglyceride levels (p = 0.02) and the Trp64Arg homozygotes, but not heterozygotes, exhibited lower triglyceride levels. Thus, this mutation appears to be associated with visceral obesity but with lower serum triglyceride. It is suggested that those with the mutation may describe a subset of subjects characterized by decreased lipolysis in visceral adipose tissue. [Diabetologia (1997) 3-adrenergic receptor; W/H ratio, waist/hip ratio; V/S ratio, visceral to subcutaneous fat ratio; NIDDM, non-insulin-dependent diabetes mellitus; CT, computer tomography.

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An air puff stimulus to the cerci of a cricket (Gryllus bimaculatus) evokes flying when it is suspended in air, while the same stimulus evokes swimming when it is placed on the water surface. After bilateral dissection of the connectives between the suboesophageal and the prothoracic ganglia or between the brain and the suboesophageal ganglion, the air puff stimulus evokes flying even when the operated cricket is placed on the water surface. A touch stimulus on the body surface of crickets placed on the water surface elicits only flying when the connectives between suboesophageal and prothoracic ganglia are dissected, while the same stimulus elicits either swimming or flying when the connectives between the brain and the suboesophageal ganglion are dissected. These results suggest that certain neurons running through the ventral nerve cords between the brain and the suboesophageal ganglion or between the suboesophageal and the prothoracic ganglia play important but different roles in the initiation and/or switching of swimming and flying. In the suboesophageal ganglion, we physiologically and morphologically identified four types of "swimming initiating neurons". Depolarization of any one of these neurons resulted in synchronized activities of paired legs with a similar temporal sequence to that observed during swimming.

Unit responses were obtained from the optic nerve of the crayfish, Procambarus clarki (Girard) with steel needles. Eighty-three repeatedly recognized elements are described. They range from bundles of primary sensory fibers to complexly reacting multimodal interneurons. Visually reacting fibers fall into two main classes, one class reacts tonically to overall illumination, the other responds to moving objects. Sustaining fibers react to increased light with increased output, dimming fibers are active in the dark and inhibited by light. Fourteen sustaining and four dimming fibers are described. The main movement fiber type, of which eleven have been found, responds to shadows. They "habituate" quickly and react best to movement of small black objects. All these fibers, and some others, are present as centrifugal elements from the other eye. Four fibers, two sustaining and two movement ones, change their fields with position of the animal. These "space-constant" fibers "look" at the sky from all positions for which possible and are otherwise "blind." Mechanoreceptive interneurons form a bundle between the first and second classes of optical fibers.Seventeen members are described. Five multimodal fibers, with combined visual and mechanoreceptor input are described. Maps of the approximate locations of the units in the cross-section of the optic nerve are presented. The number of times specific fibers were found exceeded 50 for 28.