Mo. Lopezfigueroa et M. Moller, LOCALIZATION OF NADPH-DIAPHORASE IN THE RAT PINEAL-GLAND - AN EXPERIMENTAL ENZYME-HISTOCHEMICAL STUDY, Journal of pineal research, 20(3), 1996, pp. 157-163
We have used the NADPH-diaphorase enzyme histochemical technique to lo
calize the enzyme nitric oxide synthase in the rat pineal gland. Some
scattered NADPH-diaphorase positive pineal cells were present, mostly
in the rostral part of the gland close to the pineal stalk. In additio
n, NADPH-diaphorase positive nerve fibers were located in the pineal c
apsule, in the connective tissue septae of the gland, and also intrapa
renchymally between the pinealocytes. Most nerve fibers were endowed w
ith boutons en passage. These nerve fibers remained in the gland after
bilateral removal of the superior cervical ganglia verifying a non-sy
mpathetic nature of the NADPH-diaphorase positive nerve fibers. Pineal
blood vessels also exhibited NADPH-diaphorase activity, The number an
d distribution of NADPH-diaphorase containing cells and nerve fibers w
ere not affected by bilateral superior cervical ganglionectomy. Furthe
rmore, animals sacrificed during day or night exhibited the same NADPH
-diaphorase pattern, The present investigation provides the first morp
hological evidence for the presence of NADPH-diaphorase activity in ra
t pineal cells, suggesting an influence of nitric oxide on pineal meta
bolism. Furthermore, the presence of NADPH-diaphorase activity in the
pineal blood vessels as well as in the perivascular nerve fibers sugge
sts an influence of nitric oxide on the blood flow to the gland and/or
the metabolism of the pineal cells adjacent to the blood vessels.