1. The effect of naltrexone pellets containing either 10 or 30 mg of naltrexone base on the development of tolerance and physical dependence on morphine was assessed in male Sprague-Dawley rats. ...Tolerance-dependence on morphine was induced by s.c. implantation of six morphine pellets, each containing 75 mg morphine base for 7 days. 2. Naltrexone pellet implantation blocked the development of tolerance to the analgesic and hyperthermic effects of morphine. Similarly, naltrexone pellet implantation reversed morphine withdrawal-induced body weight loss. The effect of pellets containing 10 and 30 mg naltrexone did not differ. 3. The effect of naltrexone (10 mg) pellet implantation on various signs of naltrexone-precipitated withdrawal such as body weight loss, hypothermia and increases in urinary and fecal output was investigated. Naltrexone pellet implantation did not alter the naltrexone-precipitated withdrawal-induced body weight loss. Concurrent naltrexone pellet implantation blocked the naltrexone-precipitated withdrawal-induced hypothermia, increased fecal and urinary output in morphine-dependent rats. 4. These results indicate that a single pellet of 10 mg of naltrexone can effectively block morphine tolerance and physical dependence in the rat. Such a procedure may be useful in studying biochemical, endocrinological and immunological mechanisms involved in opioid addiction processes.
"Agricultural diversification towards high-value crops can potentially increase farm incomes, especially in a country like India where demand for high-value food products has been increasing more ...quickly than that for staple crops. Indian agriculture is overwhelmingly dominated by smallholders, and researchers have long debated the ability of a smallholder-dominated subsistence farm economy to diversify into riskier high-value crops. Here, we present evidence that the gradual diversification of Indian agriculture towards high-value crops exhibits a pro-smallholder bias, with smallholders playing a proportionally larger role in the cultivation of vegetables versus fruits. The observed patterns are consistent with simple comparative advantage-based production choices. The comparatively high labor endowments of the small farmers, as reflected in their greater family sizes, induce them to diversify towards vegetables. Although fruit cultivation is also labor intensive (as compared to cultivation of staples), fruits are relatively capital intensive, making them a less advantageous choice for smallholders who tend to have low capital endowments. Furthermore, both the probability of participation in fruit and vegetable cultivation as well as land allocation to horticulture decreases with the size of landholdings in India. Small or medium holders do not appear to allocate a greater share of land to fruits or vegetables. However, the share allocated to vegetables is significantly higher if the family size is bigger, while the reverse is true in the case of fruits." from Authors' Abstract
Agricultural diversification towards high-value crops can potentially increase farm incomes, especially in
a country like India where demand for high-value food products has been increasing more ...quickly than
that for staple crops. Indian agriculture is overwhelmingly dominated by smallholders, and researchers
have long debated the ability of a smallholder-dominated subsistence farm economy to diversify into
riskier high-value crops. Here, we present evidence that the gradual diversification of Indian agriculture
towards high-value crops exhibits a pro-smallholder bias, with smallholders playing a proportionally
larger role in the cultivation of vegetables versus fruits. The observed patterns are consistent with simple
comparative advantage-based production choices. The comparatively high labor endowments of the small
farmers, as reflected in their greater family sizes, induce them to diversify towards vegetables. Although
fruit cultivation is also labor intensive (as compared to cultivation of staples), fruits are relatively capital
intensive, making them a less advantageous choice for smallholders who tend to have low capital
endowments. Furthermore, both the probability of participation in fruit and vegetable cultivation as well
as land allocation to horticulture decreases with the size of landholdings in India. Small or medium
holders do not appear to allocate a greater share of land to fruits or vegetables. However, the share
allocated to vegetables is significantly higher if the family size is bigger, while the reverse is true in the
case of fruits.
Clonidine, ICI-106270 (6-aryl 2,367 tetrahydro 5-H-pyrrolo(1,2-a)-imidazole derivative), B-HT-920 (6-Allyl-2-amino-5,6,7,8-tetrahydro-4H-thiozolo = 4,5-dazepine-dihydrochloride, and guanfacine, ...agonists at alpha 2-adrenoceptors, produced concentration-dependent contractions of the rat anococcygeus muscle. The order of potency of these agonists in producing the response was clonidine greater than ICI-106270 greater than guanfacine greater than B-HT 920. Yohimbine (10(-6) M) competitively antagonized the contractile response due to these agents acting at alpha 2-adrenoceptors. ATP (10(-6) M-10(-4) M) also produced concentration-dependent contractions of the rat anococcygeus muscle. Prazosin (10(-8) M) an alpha 1-blocker, significantly antagonized ATP-induced contractions in a competitive manner. ATP (10(-7) M) in a concentration that had no effect on basal tension of the preparation, tends to potentiate phenylephrine responses, though not significantly. The sensitivity of the anococcygeus muscle to ATP was enhanced after 24 hr (maximum catecholamine depletion period) of reserpine (5 mg/kg, i.p.) treatment. Yohimbine (10(-6) M), a selective alpha 2-blocker, significantly antagonized ATP-induced contractions and shifted the ATP concentration-response curve towards right. The antagonism was found to be competitive. The ATP-contractions were also sensitive to inhibition by reduced calcium contents (quarter or calcium free) in the Krebs bicarbonate solution. However, it was observed that ATP was capable of producing contractions of anococcygeus muscle even in Ca-free Krebs bicarbonate solution.
