Comparative Biochemistry and Physiology Part B 125 (2000) 451 – 456
Vitamin B
12
-induced alterations in activities of
-glycerophosphate dehydrogenase and malic enzyme in brain
of singi fish, Heteropneustes fossilis (Bloch)
Uma Bhattacharyya
a,b
, A.K. Dasmahapatra
a,c,
*, A.K. Medda
a
a
Department of Animal Physiology, Bose Institute, Calcutta, India
b
Department of Zoology, Vidyasagar College for Women, Calcutta, India
c
NIEHS Marine and Freshwater Biomedical Sciences Center, Uniersity of Wisconsin – Milwaukee, 600 East Greenfield Aenue,
Milwaukee, WI, 53204, USA
Received 23 November 1998; received in revised form 9 December 1999; accepted 20 December 1999
Abstract
Different doses of vitamin B
12
(0.25, 0.5, 1, 2 and 4 g/g, injected intraperitoneally for three consecutive days) altered
the activities of mitochondrial--glycerophosphate dehydrogenase (-GPD) and NADP-dependent cytosolic malic
enzyme (ME) in the brain of singi fish. The -GPD activity increased at doses of 0.5, 1, 2 and 4 g/g vitamin B
12
. A dose
of 0.5 g/g vitamin B
12
induced less activity than higher doses. ME activity increased with 1, 2 and 4 g/g of vitamin
B
12
/g. The mitochondrial and cytosolic protein content remained unchanged after vitamin B
12
administration. Cyclohex-
imide treatment inhibited the vitamin B
12
-induced increase in -GPD and ME activity. Thus, vitamin B
12
is involved in
the induction of some enzymes in fish brain. © 2000 Elsevier Science Inc. All rights reserved.
Keywords: Brain metabolism; Cycloheximide; Enzyme induction; -Glycerophosphate dehydrogenase; Fish Brain; Heteropneustes
fossilis ; Malic enzyme; Neural enzyme; Vitamin B
12
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1. Introduction
The role of vitamin B
12
in metabolism and
function of the central nervous system is well
known. In man, vitamin B
12
deficiency implicated
neurological lesion, demyelination and neuropsy-
chiatric symptoms (Reisner, 1968; Marks, 1975;
Chatterjee et al., 1996; Lovbald et al., 1997). In
rat, vitamin B
12
enhances suprachiasmatic nucleus
neurotransmitter (gamma-aminobutyric acid) con-
tent, but reduces glutamate level (Ikeda et al.,
1997). In cat, addition of vitamin B
12
in the diet
for 17 consecutive days increased choline acetyl-
transferase (ChAT) activity in the hypothalamus,
piriform lobe, hippocampus, pons and pons raphe
nuclei, but decreased ChAT activity in medulla
raphe nuclei, suggesting that this vitamin plays a
role in the activity of ChAT (Nadeau and
Roberge, 1988). The accumulation of vitamin B
12
in the rat brain maintains a diurnal rhythm; it is
highest during the active phase and transport to
the brain from the peripheral storage (in liver)
occurs during the resting phase, independent of
vitamin intake (Ikeda and Inoue, 1997).
Fish also require vitamin B
12
for growth and
survival (Julshamn and Braekkan, 1975; Mahajan
and Sharma, 1976; Mahajan and John, 1981).
* Corresponding author. Tel.: +1-414-3821746; fax: +1-
414-3821705.
E-mail address: asok@csd.uwm.edu (A.K. Dasmahapatra)
0305-0491/00/$ - see front matter © 2000 Elsevier Science Inc. All rights reserved.
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