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Central fatigue induced by intracerebroventricular infusion of AT1‐receptor blocker is influenced by serotonin content in preoptic area and hypothalamus
Author(s) -
Leite Laura Hora Rios,
Soares Danusa Dias,
Marubayashi Umeko,
Coimbra Cândido Celso
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1195.3
Subject(s) - endocrinology , medicine , hypothalamus , serotonin , chemistry , preoptic area , losartan , 5 ht receptor , thermoregulation , receptor , angiotensin ii
We previously showed that central angiotensinergic transmission plays an important role on thermoregulation and metabolic adjustments during exercise by increasing heat dissipation and modulating heat production. To asses the effect of central angiotensin AT 1 receptor blockade by losartan (Los) on serotonin content in preoptic area (POA) and hypothalamus (HP), Wistar rats were submitted to exercise until fatigue after intracerebroventricular (icv) injection of 2 μL of Los (60 nmol, n=6) or 0.15 M NaCl (Sal, n=6). Time to fatigue (TTF) and workload (W) were analyzed. At fatigue, animals were decapitated, brains were removed and POA and HP were dissected and frozen in dry ice. Serotonin (5‐HT) and 5‐hydroxyindoleacetic acid (5‐HIAA) were measured by HPLC. Los animals showed a 35% and 32% decrease in TTF and W, respectively, when compared to Sal‐treated rats. These animals showed higher levels of 5‐HT and 5‐HIAA in POA (5‐HT: 0.4±0.05 ng/mg, Los vs 0.09±0.02 ng/mg, Sal; 5‐HIAA: 2.6±0.5 ng/mg, Los vs 0.8±0.2 ng/mg, Sal, p< 0.05) and HP (5‐HT: 0.2±0.02 ng/mg, Los vs 0.06±0.03 ng/mg, Sal; 5‐HIAA: 2.4±0.6 ng/mg, Los vs 1.2±0.4 ng/mg, Sal, p< 0.05). An inverse correlation between W and 5‐HT content in the POA and HP was also found (POA: r= 0.67; HP: r= 0.63, p< 0.05). Our data suggest that central fatigue induced by AT 1 receptor blockade is related to an increase in 5‐HT content in the POA and HP. Supported by: CNPq, FAPEMIG and CAPES.