Effect of seasons on the action of 5-Methoxytryptophol (5ML) on certain thalamic and hypothalamic nuclei in the gerboas (Jaculus orientalis) Nezha BOUHADDOU Group of research on biological rhythms University Mohamed V Agdal - Rabat MOROCCO December 27
Jerboas are : - Jaculus orientalis - family Dipodidae - Asia and northern Africa - Nocturnal jumping desert rodents - Resembles mice with a long tufted tail and very long hind legs - Photoperiodic animal
Seasonal rhythms Melatonin PG Sympathic fibers SCN retina Superior cervical ganglion Bittman, 1984
5ML rhythms 5-ML (pg/glande) 1 8 6 4 2 1 Printemps Automne Hiver Spring Autumn Winter 5-ML (pg/glande) 8 6 4 2 5-ML (pg/glande) 1 8 6 4 2 8. 11. 14. 17. 2. 23. 2. 5. 8. 9. 13. 17. 2. 23. 2. 5. 8. 12. 8. 11. 14.18.2.23. 2. 5. 8. 1. 15.3 L /8.3 D 12. L /12. D 8.3 L /15.3 D 14 Concentrations du 5-ML dans les glandes pinéales en Concentration of 5ML in the pineal gland / fonction des saisons seasons 12 1 5-ML (pg/glande) 8 6 4 2 may mai august août September septembre october octobre november novembre Mois Lakhdar-Ghazal Nouria, 1992
5ML action on the reproductive cycle 4,5 LP 5ML 4 CONT 3,5 3 2,5 2 1,5 1 volume Testicular testiculaire volume (cm³) (cm3),5 mois 27/5/23 3/6/23 1/6/23 17/6/23 24/6/23 1/7/23 8/7/23 15/7/23 22/7/23 29/7/23 5/8/23 12/8/23 19/8/23 26/8/23 2/9/23 9/9/23 16/9/23 23/9/23 3/9/23 Spring Jamal Chakir, 21
OBJECTIVES To determine if the action of the 5ML depends on the photoperiodic environment and/or the period of the year. To check that the 5ML action on the SCN is season dependent.
Material and Methods 2 jerboas, females, adults, natural photoperiod Autumn Winter Spring Summer 3-5ML 2-Vehicle 3-5ML 2-Vehicle 3-5ML 2-Vehicle 3-5ML 2-Vehicle Sun rise (h = h) Injections (h 1 = h + 2h) Perfusion (h 2 = h + 3h3) - C Fos Immunocytochemistry on floating sections
RESULTS moyenne des cellules Mean of Immunoreactive cells immunoréactives 16 14 12 1 8 6 4 2 immunoréactivité C-Fos Immunoreactivity au c-fos au in niveau the whole du SCN SCNglobal *** * autumn automne winter hiver printemps spring summer été seasons saison 5ML VEHICLE Mean of Immunoreactive cells nombre de cellules exprimant le c-fos 6 5 4 3 2 1-1 Sensible Cells to 5ML in the global SCN nombre de cellules sensibles au 5ML dans le SCN global spring summer autumn winter immunoreactive cells to 5ML 5-ML (pg/glande) 14 12 1 8 6 4 2 Concentrations du 5-ML dans les glandes pinéales en Concentration of 5ML in the pineal gland / fonction des saisons seasons may mai august août September septembre october octobre november novembre Mois Lakhdar-Ghazal Nouria, 1992
- The 5ML induces C-Fos expression in the SCN during summer and autumn. The SCN would be implied in the control of the gonadic activity at these seasons. - The 5ML does not imply the SCN in it s action on the gonadic activity in spring. - The SCN is sensitive to the 5ML according to the seasons. - The amplitude of 5ML rhythm determines the sensibility of SCN to this hormone.
RESULTS Mean of Immunoreactive cells moyenne des cellules immunoréactives 16 14 12 1 8 6 4 2 immunoréactivité C-Fos Immunoreactivity au c-fos au in niveau the whole du PVT PVT+Hb global * * automne hiver printemps été saison ** ** autumn winter spring summer seasons 5ML VEHICLE - Probable implication of the PVT in the control of certain rhythmic functions by modulating the cells activity. Mean Mean of of Immunoreactive Immunoreactive cells cells 5 45 4 35 3 25 2 15 1 5 Sensible Cells Cells to to 5ML 5ML in in the the global PVT+Hb SCN spring summer autumn winter immunoreactive cells to 5ML - Modulating action of the 5ML on the seasonal expression of reproduction.
CONCLUSIONS 1. The 5ML is involved in the integration of the short photoperiod by the SCN 2. The sensitivity of the SCN is proportional to the amplitude of the 5ML rhythm in the PG. 3. The 5ML is involved in the photoperiodic control of the circannual rhythms, particularly the reproduction cycle of the gerboas. 4. The 5ML action on the neuroendocrine system, controlling the reproduction, depends on the photoperiod. 5. The 5ML has also a modulating action on the expression of the circadian rhythmic activity of certain physiological functions.
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