摘要:

The food and fluid intake, the fecal weight and weight of urine voided, urinary and plasma osmolality and neurohypophysial content of vasopressin and oxytocin were measured in groups of rats injected with oil and vasopressin (0.5 IU Pitressin tannate in oil daily, i.m.) before, during and after substitution of a 2% solution of NaCl for drinking water for 3 days. Before 2% NaCl was substituted for the drinking water, vasopressin treatment significantly decreased food and water intake (p < 0.05) and daily weight gain (p < 0.01), but no significant effect on plasma osmolality or on neurohypophysial content of vasopressin and oxytocin could be demonstrated. Vasopressin treatment did not significantly reduce the intake of the 2% NaCl solution when this was substituted for drinking water but did reduce the resulting neurohypophysial depletion of vasopressin (p < 0.01). Furthermore, on the first day of NaCl drinking, the neurohypophysial content of vasopressin in vasopressin-treated rats was increased above the control value (p < 0.05). These results suggest the existence of a negative feedback of vasopressin on its own release.

ISSN:0028-3835    

DOI:10.1159/000122387

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

The spontaneous electrical activity of the neural lobe of the cat hypophysis has been recorded. We have observed two types of activity: (1) 0.5-1.0 mV in amplitude and 4–6 msec in duration, and (2) 0.03–0.07 mV in amplitude and 1–2 msec in duration. The discharge rates of both types of activity are affected by osmotic stimuli known to influence vasopressin release. Nevertheless, only the smaller potentials were studied because they were easier to obtain. The typical response to injections of hypertonic saline was an increase in the discharge rate characterized by two peaks in the frequency-time curve. This activity seems to correspond to the unit activity described by several authors for neurosecretory hypothalamic units. Hypotonic injections cause, in about 45% of the injections, a 50% decrease in the firing rate. Injections of isotonic saline did not alter the discharge rate by the neurohypophysis. We conclude that elements in the neural lobe of the pituitary are electrically excitable and respond to stimuli known to cause vasopressin re

ISSN:0028-3835    

DOI:10.1159/000122388

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

In order to assess the generality of previous reports of enlarged genital sensory fields following estrogen treatment, facial receptive fields of individual trigeminal ganglion neurons from ovariectomized female rats injected with estrogen were compared with fields from noninjected controls. Mechanoreceptive field boundaries were determined with a series of stimulating probes varying in diameter, and calibrated according to the force delivered at the bending point (Von Frey technique). For each single unit, the threshold receptive field was determined with the smallest stimulus probe capable of reliably activating single unit discharges. Facial receptive fields from estrogen-treated females were significantly larger in area (by a factor of 10) than fields from noninjected controls. Furthermore, the increase in field area was independent of spatial location within the facial region (normally, field size decreases in a proximal-distal direction from the body trunk), and was not affected by cutting the trigeminal nerve root. Receptive field thresholds were also significantly lowered by estrogen treatment. The fact that long-term systemic estrogen treatment influences tactile sensory fields in the facial region of females suggests that this phenomenon is not peculiar to the genital region normally contacted by the male during mating.

ISSN:0028-3835    

DOI:10.1159/000122389

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Rat neurointermediate lobes were superfused in vitro and showed a stable secretion rate of MSH after 30 min. MSH secretion from lobes of untreated rats was reversibly inhibited during superfusion with medium containing 45 mM K+. This inhibition could not be induced using lobes from median eminence lesioned or reserpinized rats. Superfusion with 45 mM K+ also induced release of dopamine from lobes preincubated with the labeled transmitter. It is concluded that the MSH-release inhibiting system present in the rat neurointermediate lobe may be identical to the dopaminergic arcuate-intermediate lobe system.

ISSN:0028-3835    

DOI:10.1159/000122390

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

The effect of hypothalamic deafferentation upon levels of LH-RH in brain, cerebrospinal fluid, and plasma was studied in adult male rats. Deafferentation produced a significant increase in the LH-RH concentration of third ventricular CSF (from 140.6 to 343.9 pg/µl), while there was no change in median eminence or hypothalamic content. LH-RH in the pineal gland and the posterior pituitary was also elevated by hypothalamic isolation

ISSN:0028-3835    

DOI:10.1159/000122391

出版商:S. Karger AG    

年代:1975

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000122392

出版商:S. Karger AG    

年代:1975

数据来源: Karger