It could be associated with the genotype of these animals. However, different evidence raise the hypothesis that both pre and postnatal periods are directly related to maternal contact and contribute more significantly to the growth delay in SHR rather than the genetic susceptibility.16, 17 and 18 As previously observed,2, 4, 7, 19, 20, 21 and 22 the mean weight gain

of female SHR during pregnancy and lactation periods, SHR foetal weight, litter size and postpartum development of SHR pups PLX-4720 research buy were lower than those observed for normotensive rats. Maternal factors acting in the uterus or through the milk would have major impact on the pre and postnatal development of SHR. These factors seem to be mainly correlated with the nutrition of the foetus or newborn rat.16, 17 and 18 Alterations in the mammary gland activity were also observed in female SHR,23 with production of lower quality and quantity of milk. Clinical and experimental studies associate the reduction of salivary activity with pre or postnatal delayed development, resulted from deficient nutrition or related factors. Undernourished children PD-332991 have the stimulated SFR reduced.24 Nineteen-day-old Sprague-Dawley rats treated with a deficient protein diet

had reduced body weight and SFR.25 Deprivation of iron in the diet also decreases the SFR in 21-day-old rats, suggesting that lack of iron in this period of growth and development causes changes in the salivary gland activity.26 As observed in the present study, SHR at the different ages showed reduced salivary parameters when compared with their respective normotensive controls. We observed a significant increase in the SFR of 12-week-old in relation to 4-week-old normotensive rats. This observation is in agreement with other experimental and clinical studies that associated the SFR increase with human and animal development. Clinically, it has been demonstrated that the SFR increases progressively from childhood to adolescence.27 However, this increase was not observed between SHR at different ages. We have previously observed3 that 4-week-old SHR had reduced SFR stimulated by pilocarpine when compared

with Wistar rats Olopatadine of the same age. In the present study, reduced SFR was noted when 12-week-old SHR was compared to Wistar rat at same age. The salivary flow values (per animal weight) were not different between 4 and 12-week-old SHR. Thus, these data suggest that the altered SFR was maintained even with the growth/development of these animals. Other authors28 and 29 also observed reduced SFR after pilocarpine stimulation in 22-week-old SHRs or after isoproterenol stimulation in 16–18-week-old SHR, supposing that the SFR in SHR is reduced, regardless of the type of stimulation (muscarinic or adrenergic). All together, the results demonstrated that the reduced SFR observed in SHR was independent of the age or the rise of arterial blood pressure.