ABSTRACT
Role of serotonin in olfactory recognition was tested by depleting the olfactory bulb serotonin during postnatal day (PND)1- 4 following administration of 5,7-dihydroxytryptamine. Significant difference in the olfactory recognition test was observed during PND5-7; control pups successfully recognized and oriented towards their mother; whereas treated pups failed to recognize their mother odour. Later on, during PND12-14, both group of pups responded equally in the recognition test. Levels of olfactory bulb serotonin were depleted (53.3%) in the treated pups on PND-8, which was restored on PND-14 with only 15% variation. Further analysis demonstrated that depletion of serotonin in olfactory bulb did not affect the normal suckling and weight gain, it only modulates olfactory recognition.
ABSTRACT
Objective To study the effect of serotonergic efferent projection of the dorsal rophe nucleus (DRN) on the activity of substantia nigro pars compacta (SNc) and ventral tegmenta area (VTA) dopaminergic neurons after lesioning of the DRN by the neurotoxin 5,7-drhydroxytryptamine (5,7-DHT) in rot. Methods The changes in the firing rote and firing pattern of SNc and VTA dopaminergic neurons were observed with extrocellular recording in control and the lesioned rats. Results The results showed that the mean firing rotes of the fast-firing dopaminergic neurons of the SNc in control and the lesioned rots were (5.34±0. 13 ) Hz (n = 23 ) and ( 7.13±0. 49 ) Hz (n=37), respectively. The mean firing rote of the fast-firing dopaminergic neurons of the SNc in the lesioned rats was significantly increased when compared to that of control rots (P<0.01), while the mean firing rote of the slow-firing dopaminergic neurons of the SNc did not change. The mean firing rotes of dopaminergic neurons of the VTA in control and the lesioned rots were (5.27±0. 38)Hz (n=35) and (3.6±0.2)Hz (n=52), respectively. Lesioning of the DRN induced a significant decrease in the mean firing rote of dopaminergic neurons of the VTA. The firing pattern of SNc and VTA dopaminergic neurons changed towards a more bursting or irrgular firing after the lesioning. Conlusion These data suggest that the serotonergic efferent projections of the DRN significantly affect the activity of SNe and VTA dopaminergic neurons.
ABSTRACT
Objective: To study the effect of serotonergic efferent projection of the dorsal raphe nucleus (DRN) on the activity of substantia nigra pars compacta (SNc) and ventral tegmenta area (VTA) dopaminergic neurons after lesioning of the DRN by the neurotoxin 5,7-drhydroxytryptamine (5,7-DHT) in rat. Methods: The changes in the firing rate and firing pattern of SNc and VTA dopaminergic neurons were observed with extracellular recording in control and the lesioned rats. Results: The results showed that the mean firing rates of the fast-firing dopaminergic neurons of the SNc in control and the lesioned rats were (5.34±0.13) Hz (n=23) and (7.13±0.49) Hz (n=37), respectively. The mean firing rate of the fast-firing dopaminergic neurons of the SNc in the lesioned rats was significantly increased when compared to that of control rats (P<0.01), while the mean firing rate of the slow-firing dopaminergic neurons of the SNc did not change. The mean firing rates of dopaminergic neurons of the VTA in control and the lesioned rats were (5.27±0.38) Hz (n=35) and (3.6±0.2) Hz (n=52), respectively. Lesioning of the DRN induced a significant decrease in the mean firing rate of dopaminergic neurons of the VTA. The firing pattern of SNc and VTA dopaminergic neurons changed towards a more bursting or irrgular firing after the lesioning. Conclusion: These data suggest that the serotonergic efferent projections of the DRN significantly affect the activity of SNc and VTA dopaminergic neurons.