The Company of Biologists

Table 1.

Metabolite levels and enzyme activities in liver of rainbow trout sampled 6 h after intracerebroventricular injection into the third ventricle of 1 μl 100 g^–1 body mass of Cortland saline alone (control) or containing d-glucose (400 μg μl^–1) or l-(+)-lactate (400 μg μl^–1)

	ICV Treatment
Parameter	Control	Glucose	Lactate
Metabolite levels
Glucose (μmol g^–1 wet mass)	4.73±0.56^a	2.73±0.29^b	3.68±0.42^a,b
Glycogen (μmol g^–1 wet mass)	85.9±23.9^a	13.6±4.75^b	100.5±26.2^a
Lactate (μmol g^–1 wet mass)	3.07±0.21^a,b	3.89±0.24^b	2.91±0.20^a
α-Amino acid (μmol g^–1 wet mass)	31.2±1.18^a	24.5±1.38^b	22.2±1.10^b
DHAP (nmol g^–1 wet mass)	27.6±5.56^a	56.9±9.20^b	29.5±4.72^a
GAP (nmol g^–1 wet mass)	17.4±2.68	24.7±2.87	34.2±4.93
Glucose 6-phosphate (μmol g^–1 wet mass)	1.18±0.14^a	0.65±0.08^b	2.20±0.36^c
Enzyme activities
GK (mi.u. mg^–1 protein)	9.83±0.70^a,b	9.52±0.98^a	7.95±0.42^b
Low K_m HK (mi.u. mg^–1protein)	0.37±0.03	0.35±0.04	0.29±0.04
LDH-O (i.u. mg^–1 protein)	1.02±0.08^a	0.94±0.05^a	0.70±0.09^b
LDH-R (i.u. mg^–1 protein)	33.4±1.00^a	27.9±1.96^b	36.1±1.41^a
PK (i.u. mg^–1 protein)	0.75±0.04^a	0.65±0.05^a	0.39±0.02^b
FBPase (i.u. mg^–1 protein)	0.25±0.02	0.22±0.02	0.27±0.02
G6Pase (mi.u. mg^–1 protein)	4.53±0.31^a	3.19±0.32^b	3.33±0.32^b
GSase
Total activity (mi.u. mg^–1 protein)	352±34.8^a	400±36.8^a	234±15.5^b
% GSase^a	13.9±1.59^a	22.7±2.05^b	26.7±3.09^b
GPase
Total activity (mi.u. mg^–1 protein)	63.2±6.97	124±18.4	109±14.2
% GPase^a	48.4±7.13	49.7±2.37	55.7±5.81

	ICV Treatment
Parameter	Control	Glucose	Lactate
Metabolite levels
Glucose (μmol g^–1 wet mass)	4.73±0.56^a	2.73±0.29^b	3.68±0.42^a,b
Glycogen (μmol g^–1 wet mass)	85.9±23.9^a	13.6±4.75^b	100.5±26.2^a
Lactate (μmol g^–1 wet mass)	3.07±0.21^a,b	3.89±0.24^b	2.91±0.20^a
α-Amino acid (μmol g^–1 wet mass)	31.2±1.18^a	24.5±1.38^b	22.2±1.10^b
DHAP (nmol g^–1 wet mass)	27.6±5.56^a	56.9±9.20^b	29.5±4.72^a
GAP (nmol g^–1 wet mass)	17.4±2.68	24.7±2.87	34.2±4.93
Glucose 6-phosphate (μmol g^–1 wet mass)	1.18±0.14^a	0.65±0.08^b	2.20±0.36^c
Enzyme activities
GK (mi.u. mg^–1 protein)	9.83±0.70^a,b	9.52±0.98^a	7.95±0.42^b
Low K_m HK (mi.u. mg^–1protein)	0.37±0.03	0.35±0.04	0.29±0.04
LDH-O (i.u. mg^–1 protein)	1.02±0.08^a	0.94±0.05^a	0.70±0.09^b
LDH-R (i.u. mg^–1 protein)	33.4±1.00^a	27.9±1.96^b	36.1±1.41^a
PK (i.u. mg^–1 protein)	0.75±0.04^a	0.65±0.05^a	0.39±0.02^b
FBPase (i.u. mg^–1 protein)	0.25±0.02	0.22±0.02	0.27±0.02
G6Pase (mi.u. mg^–1 protein)	4.53±0.31^a	3.19±0.32^b	3.33±0.32^b
GSase
Total activity (mi.u. mg^–1 protein)	352±34.8^a	400±36.8^a	234±15.5^b
% GSase^a	13.9±1.59^a	22.7±2.05^b	26.7±3.09^b
GPase
Total activity (mi.u. mg^–1 protein)	63.2±6.97	124±18.4	109±14.2
% GPase^a	48.4±7.13	49.7±2.37	55.7±5.81

ICV treatment, intracerebroventricular injection; DHAP, di-hydroxiacetone phosphate; GAP, glyceraldehyde 3-phosphate; GK, glucokinase; HK, hexokinase 1;LDH-O, lactate dehydrogenase oxidase; LDH-R, lactate dehydrogenase reductase;PK, pyruvate kinase; FBPase, fructose 1,6-bisphosphatase; G6Pase, glucose 6-phosphatase; GSase, glycogen synthase; GPase, glycogen phosphorylase

Each value is the mean ± s.e.m. of N=8 fish per group. When necessary (ratios) values were log transformed prior to statistical analysis. Different letters indicate significant differences among treated groups(one-way ANOVA, P<0.05)

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