Effects of nicotine on regional blood flow in the olfactory bulb in response to olfactory nerve stimulation

Abstract

This study examined the effect of olfactory nerve stimulation on regional cerebral blood flow and assessed the effect of intravenous nicotine administration on this response in anesthetized rats. Regional cerebral blood flow was measured with laser Doppler flowmetry or laser speckle contrast imaging. Unilateral olfactory nerve stimulation for 5 s produced current (≥ 100 μA) and frequency-dependent (≥ 5 Hz) increases in blood flow in the olfactory bulb ipsilateral to the stimulus. The increased olfactory bulb blood flow peaked at 30 ± 7% using stimulus parameters of 300 μA and 20 Hz. Nerve stimulation did not change frontal cortical blood flow or mean arterial pressure. The intravenous injection of nicotine (30 μg/kg) augmented the olfactory bulb blood flow response to nerve stimulation (20 Hz, 300 μA) by approximately 1.5-fold (60-s area after the stimulation). These results indicate that olfactory nerve stimulation increases olfactory bulb blood flow, and the response is potentiated by the activation of nicotinic cholinergic transmission.

Effects of Nicotine and Its Withdrawal on The Postnatal Development of Rat Mitral Cells

“…The splitting and irregularity of the surrounding myelin sheath seen in the mitral cell axons could be attributed to the fact that nicotineinduced neuronal damage specifically targets the myelin sheath (Papp-Peka et al, 2017). The engorged blood vessels observed in this study can be explained by other investigators that reported an increase in the olfactory bulb blood flow after nicotine injection (Uchida and Kagitani, 2020). The nicotineinduced increase in the olfactory bulb blood flow was reported to contribute to the neuronal turnover in the olfactory bulb and short-term olfactory memory thus maintaining olfactory and cognitive functions (Uchida and Kagitani, 2020).…”

The relationship between olfaction and cognitive function in the elderly

“…Attentional ability, which relates to the basal forebrain cholinergic system [6,7], is the first non-memory domain to be affected in Alzheimer's disease [8]. Basic animal research has revealed that the activation of basal forebrain cholinergic neurons produces an increase in extracellular acetylcholine release in the neocortex, hippocampus, and olfactory bulb [9][10][11][12][13][14][15].…”

Influence of Intragastric Administration of Traditional Japanese Medicine, Ninjin’Yoeito, on Cerebral Blood Flow via Muscarinic Acetylcholine Receptors

“…The result of a previous study [ 37 ] showing that CBF increase by somatosensory stimulation is enhanced by NBM stimulation at a subthreshold intensity (i.e., it does not affect CBF) is similar to the present finding that NYT enhanced CBF increase in response to somatic stimulation without a remarkable increase in resting CBF. It has also been reported that a blood flow increase in the olfactory bulb induced by olfactory nerve stimulation is enhanced by pharmacological stimulation of the cholinergic system [ 24 ]. The effect of NYT revealed by the present study is not a mere vasodilatory effect; thus, it is probably due to the vasodilatory system, such as the cerebral cholinergic system, rather than NYT having a direct action on the blood vessels.…”

“…is sample size was selected based on the previous studies that examined the effect of cerebral cholinergic system activation on CBF in anesthetized rodents [10,24]. e analysis was performed using statistics software (Prism6, GraphPad Software Inc., La Jolla, CA, USA).…”

“…To be conservative, we used nonparametric tests for the statistical analyses [ 23 ], given the sample size in the present study was relatively small (6 or 7 mice/group). This sample size was selected based on the previous studies that examined the effect of cerebral cholinergic system activation on CBF in anesthetized rodents [ 10 , 24 ]. The analysis was performed using statistics software (Prism6, GraphPad Software Inc., La Jolla, CA, USA).…”