Effect of pinealectomy, adrenalectomy, pinealectomy plus adrenalectomy upon the quantification of spermatogenic cells of adult rats

The objectives of this study were to evaluate the effects of pinealectomy, adrenalectomy and pinealectomy-adrenalectomy upon the quantification of spermatogenic cells of rats. As such, 32 adult Wistar rats with a mean body weight of 331.7± 15.5g were assigned into one of the following treatments: (a) a sham-operated control group, consisting of nine animals; (b) ten pinealectomized animals; (c) seven adrenalectomized animals and (d) six pinealectomized plus adrenalectomized animals. No significant differences were observed between groups for the following parameters: body, testes, prostate and seminal vesicle weights, seminiferous tubular diameter, number of cells per seminiferous tubular cross sections (primary spermatocytes at pachytene, round spermatids, Sertoli cells) and numbers of germ cells per Sertoli cell (primary spermatocytes at pachytene and round spermatids ). Although no increase in testicular weight was observed following pinealectomy, a significant (P<0.05) increase of approximately 11.5 percent in the number of round spermatids per Sertoli cell (Sertoli cell ratio) occurred thus suggesting that short-term pinealectomy abolishes the antigonadal effect of the pineal gland upon adult Wistar rat testes

The hyperglycemia induced by angiotensin II in rats is mediated by AT1 receptors

We have shown that the renin-angiotensin system (RAS) is involved in glucose homeostasis during acute hemorrhage. Since almost all of the physiological actions described for angiotensin II were mediated by AT1 receptors, the present experiments were designed to determine the participation of AT1 receptors in the hyperglycemic action of angiotensin II in freely moving rats. The animals were divided into two experimental groups: 1) animals submitted to intravenous administration of angiotensin II (0.96 nmol/100 g body weight) which caused a rapid increase in plasma glucose reaching the highest values at 5 min after the injection (33 per cent of the initial values, P<0.01), and 2) animals submitted to intravenous administration of DuP-753 (losartan), a non-peptide antagonist of angiotensin II with AT1-receptor type specificity (1.63 µmol/100 g body weight as a bolus, iv, plus a 30-min infusion of 0.018 µmol 100 g body weight-1 min-1 before the injection of angiotensin II), which completely blocked the hyperglycemic response to angiotensin II (P<0.01). This inhibitory effect on glycemia was already demonstrable 5 min (8.9 ñ 0.28 mM, angiotensin II, N = 9 vs 6.4 ñ 0.22 mM, losartan plus angiotensin II, N = 11) after angiotensin II injection and persisted throughout the 30-min experiment. Controls were treated with the same volume of saline solution (0.15 M NaCl). These data demonstrate that the angiotensin II receptors involved in the direct and indirect hyperglycemic actions of angiotensin II are mainly of the AT1-type.

Preferential saline or water intake by pinealectomized, adrenalectomized, and pinealectomized-adrenalectomized male rats

Because the pineal gland appears to be involved in the regulation of body electrolytes, saline or water preference was investigated imn pinealecrtomized, adrenalectomized, pinealectomized-adrenalectomized, and sham-operated (SO) control rats. The pinealectomized, adrenalectomized, and pinealectomized-adrenalectomized rats exhibites increased saline consumption during teh two postoperative weeks when compared with the SO-control animals. Water intake was similar for pinealectomized and SO-control rats, but decreased for pinealectomized-adrenalectomized, and adrenalectomized rats. Although total fluid intake increased for pinealectomized, and pinealectomized-adrenalectomized rats, the proportion of saline ingested in preference to water by pinealectomized-adrenalectomized rats was twice that exhibited by pinealectomized rats. The results showed two different behaviors: increased saline intake without changes in water intake by pinealectomized rats, and increased saline intake with decreased water intake by adrenalectomized rats. However, the higher salin intake induced by pinealectomy was further increased by adrenalectomy, suggesting a direct role for the pineal gland in meidating specific salt appetite