Neonatally administered diethylstilbestrol retards the development of the blood-testis barrier in the rat.

Newborn rats were treated with 10 microg of diethylstilbestrol (DES) on alternate days from the 2nd to the 12th postnatal day, and the testes were sequentially examined up to 105 days of age by light, electron, and confocal laser microscopy. In control rats, spermatozoa and step 19 spermatids were observed in stage VIII seminiferous tubules at 56 days of age. Spermatogenic cells in DES-treated rats differentiated normally from birth until 21 days of age, after which differentiation continued only to the pachytene-spermatocyte stage. From this age onward, spermatogenic cells older than pachytene spermatocytes were not found until 56 days of age. After this point, the cells resumed differentiation and finally became spermatozoa by 91 days of age; that is, 35 days later than control rats. Electron and confocal laser microscopy showed that in the normal rat, the formation of the ectoplasmic specialization between adjoining Sertoli cells was observed as early as 20 days of age. In contrast, the specialization was not formed until 56 days of age in DES-treated rats. Furthermore, the delay in functional maturation of this structure as the blood-testis barrier was confirmed by intercellular tracer experiments. It is clear that neonatal administration of DES delayed the establishment of the blood-testis barrier for 4 weeks. Consequently, during this period, pachytene spermatocytes were exfoliated from the seminiferous epithelium without completion of meiosis.

Calcitonin gene-related peptide modulates calcium mobilization in synaptosomes of rat spinal dorsal horn.

Effects of synthetic human calcitonin gene-related peptide (hCGRP) on Ca2+ mobilization in crude synaptosomes prepared from rat spinal dorsal horn were studied using 45Ca2+ as a tracer. hCGRP promoted the influx of 45Ca2+ into synaptosomes of the spinal dorsal horn, in a dose dependent manner (at dose ranges from 10(-9) to 10(-6) M). The maximum effect of hCGRP on 45Ca2+ influx was achieved 5 min after addition of the peptide and was significantly inhibited by nifedipine. hCGRP did not alter the influx of 45Ca2+ into synaptosomes of the rat cerebral cortex, a brain area with reportedly few CGRP binding sites. In measurements of the 45Ca2+ efflux from synaptosomes of the spinal dorsal horn, 10(-7) M of hCGRP had no effect on the efflux of 45Ca2+ from the resting synaptosomes, but there was significant inhibitory effect on synaptosomes depolarized by 40 mM K+. The inhibitory effect of hCGRP on the efflux of 45Ca2+ was completely abolished by lowering the incubation temperature of the medium to 0 degrees C. The inhibitory effect of hCGRP on the efflux of 45Ca2+ was not observed in synaptosomes of the cerebral cortex. These findings suggest that hCGRP increases the levels of Ca2+ level in synaptosomes of the spinal dorsal horn, through interactions with its own receptors and the release of neurotransmitters from the nerve terminals is thus enhanced.

[Host mediated anti-tumor effect of Nocardia rubra cell wall skeleton on syngeneic tumor in mice].

The mode of action of Nocardia rubra cell wall skeleton (N-CWS) on Meth A fibrosarcoma (Meth A) was studied in BALB/c mice. N-CWS suppressed or regressed the intradermal growth of syngeneic Meth A cells in normal BALB/c and athymic BALB/c mice. The intradermally and subcutaneously infiltrated cells harvested from injection sites of N-CWS in normal mice showed in vitro cytotoxic activity against Meth A cells. Pretreatment of normal BALB/c mice with immunosuppressing agents such as hydrocortisone, carrageenan, or silica particles significantly reduced the anti-tumor effect of N-CWS. The growth of Meth A cells, rechallenged into BALB/c mice in which Meth A cells had once been suppressed or regressed by N-CWS treatment, was also inhibited, but not in similarly treated athymic nude mice. This resistant mechanism was shown to be dependent out cellular components but not on humoral components by the Winn Assay. The present results suggest that N-CWS exerts its anti-tumor activity by mediation of the immune system of the host and that the main effector cells in the early stage of tumor rejection are macrophages; T cells may also be involved in the later stage.

Release of substance P from the spinal dorsal horn is enhanced in polyarthritic rats.

Using in situ spinal dorsal horn perfusing method in decerebrated rats, we measured the release of immunoreactive substance P (iSP) in polyarthritic rats. The spontaneous release of iSP from the dorsal horn in the polyarthritic rats was significantly accelerated over that in control non-inflamed rats. Passive movements of the inflamed ankle joint evoked a significant increase in the release of iSP, while a similar movement of the non-inflamed joint led to no such increase. These results suggest that the facilitated release of iSP from the primary afferent terminals in the spinal dorsal horn in polyarthritic rats possibly plays a role in transmission of chronic pain of inflamed joints.

Calcitonin gene-related peptide promotes mechanical nociception by potentiating release of substance P from the spinal dorsal horn in rats.

In vitro superfusion with capsaicin (5 X 10(-7) M) of slices of the dorsal half of the rat spinal cord produced a significant increase in a release of immunoreactive substance P (iSP). Calcitonin gene-related peptide (CGRP: 10(-6) M) significantly potentiated the capsaicin-induced release of iSP. On the other hand, when CGRP (5 nmol/rat) was intrathecally injected, the peptide produced a significant hyperalgesia to mechanical noxious stimuli (pinching the hind paw), but aversive responses and potentiation of substance P-induced aversive responses were never observed. These findings suggest that in the rat spinal dorsal horn, CGRP potentiates the release of substance P from the primary afferent terminal and promotes the transmission of nociceptive information induced by mechanical noxious stimuli.

Possible mechanisms of positive inotropic action of synthetic human calcitonin gene-related peptide in isolated rat atrium.

The effect of synthetic human calcitonin gene-related peptide (hCGRP) on the isolated and electrically driven left atria of rats were investigated. The peptide at concentrations of 3 X 10(-9)-3 X 10(-7) M produced positive inotropic effects on the left atria in a dose-dependent manner. Verapamil (10(-5) M) and adenosine (10(-4) M) reduced the positive inotropic effect of hCGRP at concentrations of 3 X 10(-9) and 3 X 10(-8) M, but not at that of 3 X 10(-7) M. Ouabain (5 X 10(-5) M) inhibited the effect of hCGRP in concentrations of 3 X 10(-7) and 3 X 10(-8) M, but not in that of 3 X 10(-9) M. Simultaneous pretreatment with verapamil (10(-5) M) and ouabain (5 X 10(-5) M) suppressed the positive inotropy by hCGRP at all concentrations tested. On the other hand, tetrodotoxin (10(-6) M) potentiated only the positive inotropic effect of 3 X 10(-7) M hCGRP. Metoprolol (10(-7) M) and theophilline (10(-3) M) did not affect the inotropic effect of hCGRP. These results suggest that the positive inotropic effect of hCGRP is not mediated by beta-adrenoceptors but by two distinct mechanisms of action, which was inhibited by verapamil but not by ouabain (facilitation of Ca++ influx in lower concentrations of hCGRP) and which was blocked by ouabain but not by verapamil and potentiated by tetrodotoxin (inhibition of Na+/Ca++ exchange mechanism at higher concentrations of hCGRP).

Analgesia produced by microinjection of L-glutamate into the rostral ventromedial bulbar nuclei of the rat and its inhibition by intrathecal alpha-adrenergic blocking agents.

Definite and dose-dependent analgesia followed microinjection of L-glutamate into the nucleus reticularis paragigantocellularis (NRPG) of rats. This analgesic effect was inhibited by lumbar intrathecal pretreatment with phenoxybenzamine and phentolamine but not by propranolol, methysergide or naloxone. Microinjection of L-glutamate into the nucleus raphe magnus (NRM) also produced an analgesic effect which was reduced by intrathecal pretreatment with methysergide but not by phentolamine. These findings provide direct evidence that the NRPG and NRM function separately in descending pain-suppression systems of the spinal cord.