Effects of the antihypertensive drugs alpha-methyldopa and hydralazine on the performance of spontaneously hypertensive rats in the elevated plus-maze.
The effects of antihypertensive drugs on the performance of spontaneously hypertensive rats (SHR) in the elevated plus-maze were determined. Male SHR (3 months old) were submitted to long-term treatment (15 days) with alpha-methyldopa (alpha MD, 5 g/l, N = 10) and hydralazine (HYD, 100 mg/l, N = 10) given orally, diluted in water. After the drug treatment, the performance of the rats in the plus-maze was observed for 5 min in a single test and mean arterial pressure (MAP) and heart rate (HR) were then measured. The antihypertensive drugs reduced MAP significantly (mean +/- SEM: CON = 176.2 +/- 5.2, alpha MD = 157.8 +/- 4.6 and HYD = 150 +/- 4.4 mmHg) and only alpha MD increased HR significantly (mean +/- SEM: CON = 391.7 +/- 13.8, alpha MD = 453.3 +/- 14 and HYD = 368.8 +/- 18.9 bpm). The alpha MD group presented a lower total number of entries (mean +/- SEM: CON = 12.7 +/- 0.7, alpha MD = 8.7 +/- 0.9 and HYD = 12 +/- 0.9) and spent less time in the open arms than the CON (N = 10) and HYD groups (mean +/- SEM: CON = 0.69 +/- 0.04, alpha MD = 0.48 +/- 0.07 and HYD = 0.65 +/- 0.06 s). alpha-Methyldopa acts centrally and hydralazine acts peripherally. The behavioral change of SHR treated with alpha-methyldopa suggests that hypertension seems to be related to central nervous dysfunctions that are affected by an antihypertensive drug with central noradrenergic action.
Rosa
W C
WC
Departamento de Ciências Fisiológicas, Universidade Federal do Espirito Santo, Vitória, Brasil.
Oliveira
G M
GM
Nakamura-Palacios
E M
EM
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001007:Anxiety / Q000188:drug therapy*; D001794:Blood Pressure / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006830:Hydralazine / Q000494:pharmacology*; D008297:Male; D008750:Methyldopa / Q000494:pharmacology*; D051381:Rats; D011918:Rats, Inbred SHR; D013647:Task Performance and Analysis; D013997:Time Factors
D000959:Antihypertensive Agents; D006830:Hydralazine; D008750:Methyldopa